Expert Tips For Shingling A Cone-Shaped Roof

Cone-shaped roofs are one of those projects that contractors either love to do or avoid like the plague.

A prominent architectural feature on Queen Anne- and Norman-style homes, cone-shaped roofs are also found on Armenian and Georgian churches and medieval towers and castles. Their sloping and curved geometric surfaces can be difficult and labor intensive to shingle, especially for roofers who are accustomed to working only with straight lines.

Whereas a simple pitched roof typically has two or more sides and a hip roof has at least four sides, a conical or turret-style roof can appear to have an infinite number of sides. Some cone-shaped roofs have three to eight flat sides that create more of a geometric shape, such as a pyramid.

So, the challenge is: How do you install flat shingles on this intricate, rounded surface?

The underlayment should be applied vertically, perpendicular to the eave, as shown in this figure from the ARMA Technical Bulletin titled “How to Shingle a Cone Roof.” (Copyright Asphalt Roofing Manufacturers Association, reprinted with permission.)

Getting Started

Thanks to their flexibility, modern asphalt shingles can be installed on roofs of any shape.

To begin shingling a cone roof, you need to know three measurements: the length of the rafter, the diameter of the cone and the widest piece of shingle you’ll be using.

To determine the distance around the base of the cone, multiply its diameter by 3.14. For example, if the diameter is 20 feet, the perimeter would equal 62.8 feet. With a 12-inch-wide shingle, you would need 63 shingles in each row around the cone.

Precise calculations are necessary because shingle pieces will need to change shape and become narrower as you move from the base of the cone up to its peak.

Cutting the shingles is a task you can do ahead of time, by creating a template, or when you get to a particular part of the installation.

Safety Concerns

Because cone-shaped roofs are usually steep and high off the ground, consider hammering footholds into the roof for stable support while you work. Better yet, use scaffolding, which not only provides a platform for leaning a ladder onto the roof, it also serves as an easily accessible shelf for your roofing materials and tools.

On a flat-sided cone roof, use the standard hip and ridge installation method. (Copyright Asphalt Roofing Manufacturers Association, reprinted with permission.)

Underlayment and Ventilation

With preparations complete and safety equipment in place, you’re ready for the fun part: installation.

First, start by applying a good quality underlayment to the deck per the manufacturer’s instructions.

The underlayment should be applied vertically, perpendicular to the eave, following the flow pattern from the cone’s peak to its base. This process will help to prevent the material from wrinkling or buckling. You should end up with an overlap near the peak, which can be trimmed during underlayment application and before installing shingles.

Continue to overlap the underlayment vertically as you progress up the cone and use asphalt plastic cement to cement the lap edge. Alternatively, you can use a peel-and-stick underlayment. A self-adhering underlayment protects the eaves and flashing from wind-driven rain and covers any possible gaps between abutting shingles.

Next, check the ventilation. If the cone is open to the attic area, it should be part of the ventilation system. To accommodate static ventilation in the main portion of the attic, increase the requirement for the net-free area by the same square footage as the cone-shaped room. If the area is open to the living space, a ceiling fan can help force moisture and heat from the cone-shaped room to the main living area for dispersal. Using a room dehumidifier may also be helpful.

When working with a completely circular cone, use an off-peak, roll-type ridge vent at the peak for positive ventilation. The formula for cone-shaped rooms is consistent with any other residential area:

  • Equal intake and exhaust vents: 300 square feet of attic area = 1 square foot of net-free vent area
  • Exhaust vents only: 150 square feet of attic area = 1 square foot of net-free vent area

In cases with no ventilation, make the homeowner aware of potential issues with accelerated wear and how it can affect the product’s warranty. For more specific requirements, contact the shingle manufacturer.

Shingling Flat-Sided vs. Rounded Cones

After installing underlayment and addressing ventilation, you can start applying shingles.

When shingling a rounded cone roof, divide the roof into three distinct zones. (Copyright Asphalt Roofing Manufacturers Association, reprinted with permission.)

If you’re working with a flat-sided cone roof, you can use the standard hip and ridge installation method. Snap vertical chalk lines from the cone tip to the eave center on each of the flat sides. Then apply shingles to the flat areas, cutting at the hips or joints. Use a standard hip and ridge shingle to complete the hip joints.

To ensure a continuous roofing line, snap horizontal chalk lines around the cone so that shingles will line up on adjacent sides.

Shingles on steep-sided cone roofs — those greater than 21/12 slope — may need to be hand sealed with asphalt plastic cement. Check the manufacturer’s instructions for steep-slope application.

When shingling a rounded cone roof, you won’t have a horizontal line to follow because of the curvature. If you try to create a line, butting the sides of the shingles together, the shingles will gradually curve downward and won’t correctly align when you encircle the cone.

To make installation easier, divide the roof into three distinct zones. Start applying shingles to zone one, at the bottom of the cone, and then work your way up to zones two and three.

While you are nailing, have another crew member help hold the shingles down around the curve so they are flush against the surface.

Side overlap of shingles is more noticeable in the upper portions of each cone. Trim shingles at an angle to make the joint parallel to water flow. (Copyright Asphalt Roofing Manufacturers Association, reprinted with permission.)

Because the cone shape tapers from the base to the peak, succeeding courses require less material.

The degree of horizontal offset and varied shingle cutouts will create a random appearance. When using standard three-tab shingles, trim each shingle for proper vertical alignment. A simpler alternative would be to use a randomly applied shingle that doesn’t need to be vertically aligned.

Shingling a cone-shaped roof may be challenging, but with the proper knowledge and execution, you can restore this architectural focal point to its full glory.

For more information from Atlas Roofing, including technical bulletins, installation instructions and product data sheets, visit atlasroofing.com.

Three Shingle Installation Mistakes That Cause Major Problems

By following installation guidelines, contractors can produce a more professional-looking roof that will be far less likely to experience problems a year, two years, or even 10 years down the road.

A roof that isn’t installed precisely the way it was intended can be both unattractive and incapable of standing up to extreme weather conditions. On a laminate shingle roof, overlooking seemingly small details, such as shingle alignment and nailing, can lead to serious problems. Here are some of the most common details that, when improperly executed, can have negative consequences later in the installation or after completion of the roof:

  1. No Starter Shingles/Improper Alignment of Shingles at Eave and Rake

CORRECT: This photo shows the starter shingle being installed correctly. Proper alignment is crucial when installing the starter shingles. Photos: Atlas Roofing

The starter shingle’s two purposes are water protection and wind protection at the eave and rake. A starter shingle is used to seal with the field shingle at the first course along the eave and rake. This helps prevent wind and water from getting beneath the shingle in this critical location. The underlayment is a secondary water barrier if any moisture gets beneath the shingles.

Starter shingles are installed so they overhang the edge of the eaves slightly to allow for water runoff. Then a course of shingles is installed on top of the starter shingles, forming a front line of defense for blow-offs and water damage.

INCORRECT: When starter shingles are not installed, water channels can form where the shingles align across the first course. Photos: Atlas Roofing

When roofers don’t use starter shingles and install the first course of shingles directly onto the eave or rake, water channels can form where the shingles align across the first course. Moisture can then come into direct contact with the roof deck. Shingles farther up the roof are protected by the courses beneath them, which catch and divert any water that happens to drip between the edges. The first course of shingles needs the same defense from the elements.

Tip: Proper alignment is important when installing both the starter shingles and the first course of shingles. If the starter shingles are not secured correctly at the eave or rake, and the first course of shingles is not nailed down evenly across the top of the starter shingles, the roof may be at risk for wind and/or water damage.

Manufacturer’s guidelines for the proper overhang spacing at the drip edge or rake should be followed precisely. If the starter shingle overhangs the eave too much, a gust of strong wind may lift the shingles and cause a blow-off.

  1. Improper Nailing

The obvious purpose of proper nailing is to ensure that shingles stay in place and don’t cause leaks. Local building

INCORRECT: Nail heads should be flush with the top of the shingle. All three of the nails in this photo are incorrectly installed. The nail on the left is over-driven, the middle nail is at the wrong angle, and the one on the right is under-driven. Photos: Atlas Roofing

codes and manufacturers’ instructions give roofing contractors the directions they need to fasten the shingles properly to the roof deck. Guidelines specify the number of nails per shingle and where the nails should be placed.

In laminate shingles, the nailing zone is referred to as the “common bond” area of the shingle. The “common bond” area includes the double-layer portion of the shingle down to the exposure and constitutes the proper nailing area as identified in laminate shingle installation instructions. The “common bond” nailing area must be targeted correctly in order to obtain the proper wind performance as advertised by the shingle manufacturer. Properly

INCORRECT: The nailing area must be targeted correctly in order to obtain the proper wind performance. In this photo, nails are improperly placed both above and below the common bond area. Photos: Atlas Roofing

placed nails go through two layers of shingles – penetrating through the previous shingle course underneath – attaching them securely to the roof deck. Nails placed outside the common bond area can void the roof’s warranty and prevent asphalt shingles from performing as intended during extreme weather.

Tip: Pneumatic nail guns are popular among many roofers. The pressure on the gun should be set correctly before use. Nail heads should be flush with the top of the shingle. If the pressure is set too high, the gun will overdrive the shingle, causing it to sink into the mat. Too low, and nails will be under-driven, meaning they will stick out above the top of the shingle. Incorrect pressure can also cause nails to be driven in diagonally.

Wind and wind-driven rain can lift improperly nailed shingles and cause water damage to the roof and possibly blow-offs. Using either too many or not enough nails can weaken the shingle’s performance, which can also result in blow-offs.

Finally, roofers who prefer hammers should be skilled enough to drive nails consistently into shingles at the right angle, not over- or under-drive them.

  1. Improper Shingle Alignment

Roof shingles are intended to be precisely aligned, both vertically and horizontally. Roofers lay out each course of

INCORRECT: Proper alignment of the shingles is crucial. In this photo, the top shingle has been placed too high. Photos: Atlas Roofing

shingles in a staggered, stepped pattern (think of a brick wall). The shingle edges of one course must be offset from the shingles below. Edges lined up with each other would allow water to seep through to the roof deck.

INCORRECT: The shingle at the top of this photo has been placed too low. Photos: Atlas Roofing

Installing shingles too high or too low compared to the previous course can affect the exposure, which in turn would affect the aesthetics, wind performance and seal strength of the roof. An improperly aligned shingle course would be very noticeable and have a wavy appearance that is unattractive and amateurish.

Tip: Manufacturer’s instructions for proper shingle alignment are printed on the shingle wrapper.

Eliminating Problems Pays Big Dividends

Roofers who are careful to avoid these mistakes can avoid unintended problems after installation. Using a starter shingle at the eaves and rakes can ensure that the installation is off to a good start. Paying attention to proper nailing and nail placement within the common bond area on all courses all the way up to the ridge can optimize the roof’s performance against wind and rain. Finally, carefully aligning each course of shingles both vertically and horizontally will give the finished roof a professional appearance and help to improve the homeowner’s curb appeal.

Replacing a Roof Drain on a Structurally Sloped Steel Roof Deck

Figure 1. Roof drain detail. Photos: Hutchinson Design Group Ltd.

What is the number one goal of any building owner when it comes to the roof? They don’t want water pouring through their ceilings damaging the interior of the building. How do you keep water out of the building? By keeping the water on the exterior of the building and directing it to the roof drains or other drain locations, such as scupper or gutters. The roof drain is, on a basic level, one of the simplest details on the roof, and yet it is flashed incorrectly time and time again. This paper will walk you through the process of replacing a roof drain on a structurally sloped steel roof deck and installing the new roof system and flashing.

Photo 1. The sump pan and drain body have been installed. Photos: Hutchinson Design Group Ltd.

First off, we are going to assume that the current drainpipe is adequate to handle the existing water volume and drain its portion of the roof, and that the drain pipe is in good condition. Our new roof system will meet the current R-30 requirements for continuous insulation above the roof deck in a roof near Chicago. So, our roof system will be composed of a mechanically fastened substrate board on the steel roof deck, a self-adhering vapor retarder, two layers of 2.6-inch insulation mechanically fastened, a 1/2-inch modified gypsum cover board set in bead foam adhesive, and fully adhered EPDM membrane. (See Figure 1.) We will also assume that the roofing contractor is acting as the general contractor for our scenario.

Now that we have our parameters out of the way, what’s first? I have never met a building owner that likes construction debris inside of their conference room or classroom, so the interior needs to be protected prior to the removal of the existing roof drain. This can be as simple as some Visqueen, but the interior protection needs to be installed prior to the removal of the existing roof drain. The one question that seems to come up is, who is installing this protection? The owner? The plumber? The roofing contractor? I like to put this on the plumber. He knows when he is removing the drain and installing the new one.

Once the interior protection is installed, we need to coordinate the removal of the existing roof system and installation of the vapor retarder with the removal of the existing roof drain, as well as the installation of the new metal sump pan, drain body and lead and oakum joint to the existing drain pipe. (See Photo 1.) This all needs to be done on the same day so that the roof can drain properly and that the vapor retarder can be terminated onto the roof drain flange. This part is critical, as with experience this designer has learned that the vapor retarder can be used as the seal between the extension ring and the roof drain flange and that the O-ring can be eliminated. The sump needs to be fastened to the roof deck around the perimeter at 8 inches on center and be centered on the drainpipe. The drain body then needs to be set over the drainpipe and lead and oakum installed between the drain body and drain pipe.

Installing the New Roof

So, now we have the roof drain body and the vapor retarder installed. Now comes the new roof system. To meet our R-30 requirements, we are going to need a base layer of 2.6-inch polyisocyanurate insulation and 4-foot-wide, 1/2-inch-per-foot tapered insulation sump around the roof drain. This sump will get us to the R-30 requirements of 4 feet from the roof drain as required by the current codes. If my math is correct, that will leave 3.1 inches of insulation at the roof drain. We will need a reversible collar and threaded extension ring to accommodate this height. When setting the reversible collar onto the drain bowl, set it in water cut-off mastic. If the drain ever becomes clogged, this will help to keep water from seeping under the reversible collar and into the roof system. Next the threaded extension ring is installed. First, install some water cut-off mastic onto the treads prior to engagement with the reversible collar. Once again, this will help to prevent water from entering the roof system if the drain becomes clogged and backs up.

Photo 2. The extension ring has been set lower than the cover board (yellow) and water cut off mastic has been installed on the extension ring flange. Photos: Hutchinson Design Group Ltd.

One of the main questions that I receive from the roofing and plumbing contractors is, “How high should I set the extension ring?” Well, it varies per roof system, but for our scenario it needs to be set flush with the top of the tapered insulation. We set it here because we have our cover board that has yet to be installed, and when the clamping ring is installed it will be lower than the cover board. Now back to the insulation; the 2.6-inch insulation should be installed as close to the extension ring as possible, chamfered as required to fit under the flange. Next the tapered insulation sump is installed. This should be installed as close as possible to the extension ring flange and chamfered as required to fit beneath the flange. All voids between the extension ring and the insulation should be filled with spray polyurethane foam insulation.

Once we have our insulation installed, next comes the cover board. The number one thing with the cover board and roof drain is having the cover board cut perpendicularly to the roof drain flange. (See Photo 2.) Do notchamfer the cover board. Chamfering the cover board may ease the transition of the membrane onto the extension ring flange, but it creates an unsuitable substrate surface for the bonding adhesive. And in my experience, water seems to end up ponding around the roof drain and not dropping into the roof drain. This will also allow the roof’s drain clamping ring to sit flat and below the roof surface of the roof.

Photo 3. The membrane has been correctly cut in a cloverleaf pattern. Photos: Hutchinson Design Group Ltd.

Now that our cover board is installed, we have the membrane and its transition into the roof drain. Water cut-off mastic is to be installed on the extension ring flange. How much you ask? One tube. Load that flange up. Make two thick beads with it. I have never heard a contractor say, “Man, using all of that water cut-off mastic on the job really set me back.” It’s a small item, but it is worth it.

After the membrane has been installed and the clamping ring is set, it’s time to cut a hole in the membrane to allow the water to get to the drain and off the roof. How big should the hole be? As small as possible is what some contractors might say. I ask a question to you now: what is the goal of the roof drain? If you answered to get the water off the roof as quickly as possible, you would be correct. Then why would the contractor want to cut a small hole in the roof membrane that would restrict the flow of water into the roof drain piping and off of the roof? I am dumbfounded as well. When we detail the roof drain, we call for the membrane to be cut back to within a 1/2 inch of the extension ring in a cloverleaf pattern around the clamping ring bolts. (See Photo 3.) This way there is no confusion on how far back the membrane is to be cut. Set the drain dome and the roof drain detail is complete.

So, there you have it. Now the roof can drain properly with a brand-new roof drain with no problem (fingers crossed).

Fact or Fiction? Mixing Exhaust Vent Types Is Problematic

Too often, attic exhaust vent types are mixed, which can short-circuit the airflow pattern in the attic space. Photo: Jerry Becker

Airflow dynamics dictates avoiding it. The manufacturers’ Installation Instructions caution against it. Building Code cites it as a violation. And yet it remains one of the most questioned, challenged and, unfortunately, ignored tips offered during our best practices in residential attic ventilation seminars.

Is it really a problem to mix or combine different types of attic exhaust ventilation (ridge vents, wind turbines, gable louvers, box vents and power fans) on the same roof above a common attic? And if it is, why will you see it so often driving through any city in North America?

Lack of information, misunderstanding the science, and resistance to breaking old habits all contribute to the persistence of mixed exhaust vents on today’s roofs. We asked roofing contractors to share their experiences to help explain what could go wrong.

Problem No. 1: Inefficient Airflow

The main reason combining different types of exhaust vents is problematic is that it disturbs the proper flow of the attic air. To best help fight heat buildup, moisture buildup and ice dams, attic ventilation must be a balanced system of intake vents (placed low on the roof in the soffit or at the roof’s edge) and exhaust vents (placed at or near the roof’s peak). This allows the incoming cooler, drier air to enter the attic at the lowest possible location, flush out any built-up heat and moisture from inside the attic all along the entire underside of the roof deck, and push it out through the exhaust vents high on the roof.

Power fans are a good exhaust vent option. So are ridge vents. But not when they are mixed together on the same roof above a common attic. Doing so could lead to inefficient airflow and weather infiltration. Photo: Sean Toms

But, if two or more different types of exhaust vents are in place, it short-circuits the system. Instead of the primary path of air being into the intake vents and out of the exhaust vents, the path is mostly between the two styles of exhaust vents. One of the types of exhaust vents becomes an intake vent because air will always follow the path of least resistance. Air will always look for the easiest, closest path to take. That path happens to be between the two types of exhaust vents. And that limits the distribution of the air to the upper region of the roof; or worse, it keeps the air circulating between the distances of the two vents closest to the peak. That is not the best way to remove heat and moisture buildup inside an attic.

“About five years ago, I had a seasoned roofer with me that just started working for our company,” recalls roofing consultant Jerry Becker, Roof Life of Oregon, Tigard, Oregon. “We walked up to this apartment complex and I noticed that there was a power fan alongside can vents (box vents) and very little intake ventilation. I placed a friendly bet with him stating that I know what the plywood already looks like underneath without looking at it. He argued with me and said, ‘This roof has plenty of ventilation; look at all the vents up top and it even has a fan!’ So, I told him that the plywood next to the fan and the closest can vents and up to the ridge is going to be perfect, but as soon as you drop down about a foot from the power fan the plywood will be as black as night.

“We go inside the attic and what do you think we found? Black microbial growth on the lower section of the roof. It was so black that it was wet. It is important not to mix exhaust vent types. It’s bad enough when you do it on a single dwelling home, but that same mistake in a multi-family home is deadly. Think of all the moisture that is created by all the families — the washer/dryer, dishwasher, sinks, showers and ourselves.”

Inefficient airflow not only can damage the roof deck but it can also prematurely age the asphalt shingles. “I see examples of this all the time,” says Trevor Atwell, owner, Atwell Exterior Services LLC, Greenville, North Carolina. “Premature aging of roofing materials, buckled sheathing and signs of rotten wood all due to the moisture and heat being trapped.”

Ironically, sometimes the desire to mix types of attic exhaust vents seems reasonable on the surface. The homeowner or the roofing contractor wants to improve the flow of air. Thus, adding more vents — even if they are different types — seems logical. But more is only better in this case if it’s more of the same type. If improved airflow is the goal, double-check if the correct type of exhaust vent is being used to match the size and design of the roof/attic and if it’s being supplied with a balanced amount of intake ventilation. Mixing exhaust is not the solution.

Box vents or power vents installed near a ridge vent can lead to inefficient airflow, which can damage the roof deck and prematurely age asphalt shingles. Photo: Trevor Atwell

“I have seen this in action and until it was explained to me why I should avoid it, the concept of mixed exhaust was a mystery I had to punt to a colleague or competitor” says Tim Chapin, owner, Your Safe and Healthy Home, Akron, Ohio. “I had a condo project with a very complex roof made even worse by the presence of ridge vents, gable vents, soffit vents, and box vents. I was amazed there was a problem because it seemed to be ventilated to the max. But now I know it was short-circuited.”

“We see it often with ridge vents and a power fan just below the ridge vent, or with box vents combined with ridge vents; sometimes all three. We call it the Ventilation Trifecta,” says Tom Picha, steep slope consultant, Affordable Roofing Inc., Aurora, Illinois. “More is good in some cases. Not all.”

“I had a house I was asked to inspect. The house had a ridge vent, box vents and vented drip edge on it,” says Jeffrey Heitzenrater, owner, Triple Peaks Roofing & Construction Inc., Westlake, Ohio. “The first thing wrong was two different types of exhaust vents. Upon a complete attic inspection, we found mold and mildew. The insulation was also packed tight at the bottom, blocking off the intake system the previous company installed. This particular roof was only eight years old and all the plywood is now bad. This was caused from the trifecta — no intake, box vents turning into intake and venting out of the ridge vent.”

Problem No. 2: Weather Infiltration

When you ask a vent to perform a task it has not been designed to tackle, you’re rolling the dice against Mother Nature. An exhaust vent mixed with another type of exhaust vent that suddenly is pulled into intake airflow duties as a result of short-circuiting is not only pulling in air, but whatever the air is carrying that very moment: rain, snow, debris. Exhaust vents are not designed to ingest anything.

One of the consequences of mixing attic exhaust vent types can be weather infiltration, such as the snow in this photo. Photo: Ron Bastian

“In the winter when freezing rain turns into fine ice particles, I observed several times the lower exhaust vents on the roof becoming intake vents instead of exhaust as designed and drawing in ice particles and snow,” says Steve DuCharme, owner, Innovative Builders Roofing & Construction, Edmond, Oklahoma.

“I have witnessed snow ingestion into the attic due to mixed exhaust vents,” says Corey Ballweg, owner and president, Mid Towne Construction Inc., Cross Plains, Wisconsin.

“I recall an attic several years ago that had ridge vent and two power fans. They installed two because they were told one wouldn’t pull enough heat out,” says Paul Vosen, president, Degenhardt Home Improvement, Madison, Wisconsin. “The house had no overhangs and the attic floor was insulated with a good vapor barrier. I was there in the rain and both power fans were running. The attic was so tight that the power fans were actually pulling rain in through the ridge vent. Never have I seen that before — nor have I seen it since, but I never forgot it.”

The weather infiltration problems that can result from mixing exhaust vent types may not catch a homeowner’s attention right away. Not many homeowners regularly check their attic.

“I worked on a roof that did not have any intake vents at the soffit but did have two gable vents in addition, a power fan, and four box vents,” says Scott Dennison, president, Dennison Exterior Solutions & Gutter Topper, Saint Joseph, Michigan. “Over the brief 15-year life of the roof, when the power vent would turn on it turned the four box vents into intake vents which sucked water into the attic and destroyed the roof deck adjacent and below the vent.”

The most common exhaust mixture our seminar attendees tell us they see: gable end louvers combined with something else. Often the homeowner demands that the roofing contractor leave the gable end vent in place despite the fact a ridge vent is being installed as an exhaust vent improvement. The homeowner’s reasoning: The gable louver adds a decorative touch to the home’s exterior. Solution: Do what Ron Bastian does.

“I’ve noticed snow and wind-driven rain coming in a gable end vent which was combined with a ridge vent,” says Bastian, owner and president, Bastian Roofing Inc., Richfield, Wisconsin. “We closed up the gable end vent from inside the attic and this cured the problem I was called out for.” By closing up the gable vent from inside, the attic short-circuiting is eliminated and the homeowner can still enjoy the cosmetics from the exterior.

“We have witnessed numerous issues related to short-circuiting,” says Shawn Bellis, owner, EPIC Exteriors, Overland Park, Kansas. “We’ve seen fine wind-driven Midwest snow sucked into the exhaust vents — gable vents mixed with ridge vents, for example.”

There’s a Much Better Way

Inefficient airflow, mold, rotted decking, prematurely aging shingles, and weather infiltration into the attic does not have to be the final outcome. There’s a better way, but it may take a commitment to educating the homeowner and fellow roofing contractors. I believe that’s one of the reasons our best practices seminars are so well received.

“I had mixed attic ventilation on my own home,” says Sean Toms, quality control inspector, S & K Roofing, Eldersburg, Maryland. “After attending the seminar a few years ago, I looked in my attic. I had condensation on the roof nails. I had a ridge vent, fully vented soffit and gable vents. I closed the gable vents and added insulation to my attic floor. Problem solved.”

“I seem to run into mixed exhaust vents every week. Homeowners think that the more types of ventilation on the roof the better they are,” says Richard Turner, owner, RJ Turner Remodeling, LLC, High Point, North Carolina. “After explaining the things I have learned in the Air Vent Inc. seminars, they quickly understand the correct way things should be done.”

About the Author: Paul Scelsi is marketing communications manager at Air Vent Inc., and leader of its Attic Ventilation: Ask the Expert™ seminars. He’s also chairman of the Asphalt Roofing Manufacturers Association Ventilation Task Force. For more information, visit www.airvent.com.

Three Polyiso Roof Insulation Options to Simplify Your Next Job

Pre-fabricated roof sumps direct water to a center drain point, helping to ensure proper drainage and minimizing installation time. Photos: Hunter Panels

As a roofing professional, you undoubtedly are familiar with polyiso insulation, as it is used in 70 percent or more of the commercial roofs in North America. Polyiso is popular with roofing professionals because it offers a high R-value per inch, is affordable, readily available, compatible with many roofing systems and meets both FM 4450 and UL 1256.

While you likely have specified or installed flat stock polyiso products, you might be less familiar with specialized product make-ups, which can help you simplify roof insulation jobs. Three options to be aware of are:

  1. Tapered systems
  2. Pre-cut hips and valleys
  3. Pre-fabricated sumps

Tapered Systems

As roofing professionals know, water is the enemy of the roof assembly. To prevent ponding and provide a positive slope to drain, polyiso insulation manufacturers offer sloped panels. Tapered polyiso typically comes in 4-foot-by-4-foot or 4-foot-by- 8-foot panel sizes, and in various compressive strengths. Commonly available slopes (per foot) include 1⁄16 inch, 1⁄8 inch, 3⁄16 inch, 1⁄4 inch, 3⁄8 inch and 1⁄2 inch. Tapered systems range from two-panel to eight-panel repeats, with such systems including varying thicknesses of flat polyiso insulation to complete the taper profile.

Photos: Hunter Panels

Tapered polyiso insulation installs similar to flat stock polyiso insulation, using adhesives or fasteners. As with multi-layer flat stock installations, when installing tapered products, crews should stagger the joints between layers to reduce potential pathways for airflow and condensation within the insulation layers.

Full-service polyiso manufacturers can design a tapered insulation layout based on the roof plan and specified R-value. They then will provide shop drawings showing where to place each tapered and flat stock panel to ensure positive slope and effective drainage across the entire roof.

Pre-Cut Hips and Valleys

In addition to the one-way sloped tapered panels discussed above, roofing professionals have access to pre-cut hips and valleys made of polyiso insulation. The hips and valleys help direct water on more complex roof designs. Well-equipped manufacturers will custom design and fabricate pre-cut, one-piece polyiso hips and valleys to meet your jobsite requirements including slope, and minimum and maximum thicknesses.

While crews can form hips and valleys by field-cutting tapered panels, ordering the pre-cut, one-piece panels reduces labor time and costs, as well as dumpster fees. It also prevents material waste caused by cutting errors.

Pre-Fabricated Sumps

Going a step farther in slope complexity, and further reducing ponding water, some polyiso insulation manufacturers offer pre-fabricated roof sumps. Commonly available as 4-foot-by-4 foot panels that ship flat, pre-fabricated sumps direct water from four directions to a center drain point. Some manufacturers also offer 8-foot-by-8-foot hinged sumps for greater design flexibility. All of these sumps offer a variety of starting thicknesses at the drain from 1/2 inch to 2 inches.

Choosing a Polyiso Supplier

Roofing professionals can obtain polyiso roof insulation from several suppliers. Which one is right for you? Following are a few factors to consider to help simplify your next roofing job.

  • Access to technical support: Some polyiso manufacturers provide customers with a variety of technical services. Having access to designers and estimators who work every day with specialized polyiso products takes the guesswork out of the process for you, saving time and money while helping ensure a high-quality roof.
  • Ready availability: Choosing a supplier with facilities throughout the country helps ensure timely access to specialty polyiso insulations when you need them.
  • Training support: To help your crews get up to speed faster on working with specialized polyiso roof insulation systems, look for a manufacturer that offers training support — whether via online videos, in person or on the jobsite.

Ponding Water Basics: Proper Drainage Design and Low-Slope Roofs

Roofing professionals install a new asphalt roof on the Broward County Stephen Booher Building in Coral Springs, Florida. Photo: Advanced Roofing Inc.

A low-slope asphalt roofing system is cost effective, durable and reliable. Multiple layers of weatherproof membranes protect a building, its residents and the property it houses. There are a few design elements that will help building owners get the most from their roofing system. Managing ponding water is essential to properly maintaining a roof.

Ponding water is defined as the water which remains on a roof 48 hours or longer. Water may accumulate on a low-slope roof due to rain, snow or runoff from rooftop equipment. Ponding water can have major negative consequences, regardless of the type of roofing system. Proper design, installation and maintenance of roofing structures can prevent this condition and its associated problems.

The adverse effects of ponding water on roofs can include:

  • Deformation of the deck structure:Ponding water can substantially increase the load on roof decks. As water accumulates, deck deflections can increase, thereby resulting in additional ponding water, which could compromise the structural integrity of the deck.
  • Damage to the roof surface:Ice formations develop and move constantly with changes in temperature. This movement can “scrub” the roof membrane to such an extent that considerable physical damage to the membrane can occur.
  • Growth of algae and vegetation:When water stands for long periods of time, algae and vegetation growth will likely occur, and may cause damage to the roof membrane. Additionally, vegetation can clog drains and cause additional ponding.
  • Accumulation of dirt and debris in the ponding area:Dirt, debris, and other contaminants can affect and damage the membrane surface. The can also lead to clogged drains.

Proper design and installation are crucial factors in roof system performance. This photo shows an Atactic Polypropylene (APP) modified bitumen membrane being applied by torch to a low-slope roof. Photo: ARMA

Ponding water may lead to accelerated erosion and deterioration of the membrane surface that can result in failure of the roof system. Allowing even relatively small amounts of moisture beneath the roof membrane may reduce the thermal efficiency of the insulation. More importantly, moisture intrusion can cause serious damage to the deck, insulation, and membrane as well as the building’s interior.

The Asphalt Roofing Manufacturers Association (ARMA) recommends that roof designs provide adequate slope (minimum of ¼ inch per foot) to ensure that the roof drains freely throughout the life of the building and to thereby avoid the effects of ponding water. Model building codes also require a minimum ¼ inch per foot slope for new construction projects, and require positive drainage for re-roofing projects. These requirements are intended to prevent water from ponding on roof surfaces.

Managing Ponding Water

Here are a few best practices to manage ponding water:

  • Adequate sloping should be taken into account during the design process. A roof’s structural frame or deck should be sloped, and drainage components like roof drains and scuppers should be included in the design.
  • In addition, secondary (or emergency) drains may be required by local plumbing codes to help reduce the risk of a structural failure due to clogged drainage systems. Talk to your roof membrane manufacturer and/or roof system designer to determine the proper location of these components.
  • If a deck does not provide the necessary slope to drain, a tapered insulation system can be used. A combination of different approaches — single slope, two-way slope, and four-way slope — is often used to achieve the necessary slope and to allow for moisture drainage.
  • Additionally, crickets installed upslope of rooftop equipment and saddles positioned along a low-point between drains, can help prevent localized ponding in conjunction with a tapered insulation system.
  • Building designers and owners should work with contractors and roof manufacturers to determine which methods are best and appropriate for a roof assembly’s long-term performance, whether it’s a new construction or re-roof project.

The NRCA Roofing Manual: Membrane Roof Systems—2015, states the following: “NRCA recommends that designers make provisions in their roof designs for positive slope.”

The manual spells out that slope generally is provided by:

  • Sloping the structural framing or roof deck
  • Designing a tapered insulation system
  • Proper location of roof drains, scuppers and gutters
  • A combination of the above

By following the proper drainage practices detailed above, building owners can positively impact their low-slope roofing system and help to ensure it will remain durable and reliable throughout its service life.

To obtain specific information about ponding water on particular products and systems, contact your roof material manufacturer. For more information about low-slope asphalt roofing systems, visit www.asphaltroofing.org.

Proper Storage and Handling of Polyiso Insulation

Photo: SOPREMA

Punxsutawney Phil certainly got it right this year; we have had six more weeks of winter — and then some — particularly in the Northeast. As winter turns to spring, building and repair projects which frequently involve the roof get underway. As you commence these new and re-roofing initiatives, here are a few key considerations about the storage and handling of polyiso roof insulation on a jobsite.

Storage

Polyiso insulation is typically shipped protected by a plastic wrap, plastic bag or both. This factory packaging is intended for handling the polyiso in the manufacturing plant and during transit; it should not be relied upon as protection at jobsites or other outdoor storage locations unless specified otherwise by the manufacturer.

Material delivery should be carefully coordinated with the roof application schedule to minimize outdoor storage. When short-term outdoor storage is necessary, whether at grade or on the roof deck, the following precautions should be observed:

  • Bundles should be stored flat above the ground utilizing included feet or on raised pallets. If possible, the bundles should be placed on a finished surface such as gravel, pavement, or concrete rather than on dirt or grass.
  • Unless specified otherwise by the manufacturer, cover the package and pallet with a waterproof cover, and secure to prevent wind displacement.

Note: Polyiso insulation is fully cured and fit for installation upon delivery. No additional storage time is required.

Handling

Photo: Johns Manville

Exercise care during handling of polyiso insulation to prevent breaking or crushing of the square edges and surfaces. Remove the polyiso bundles from trucks with proper equipment. Other means of mishandling, such as pushing pallets off the edge of the truck or “rolling” the pallet across the roof deck, must be avoided.

Product Application

Polyiso should always be installed on dry, clean roof decks in dry conditions. Follow the manufacturer’s recommendations regarding product application to ensure performance to the intended design life of the roofing system. Apply only as much polyiso roof insulation as can be covered by completed roofing the same day.

Construction Traffic

Avoid excessive traffic during roof construction of or on a completed roof surface. Although polyiso has been designed to withstand limited foot traffic, protection from damage by construction traffic and/or abuse is extremely important. Roof surface protection such as plywood should be used in areas where storage and staging are planned and heavy or repeated traffic is anticipated during or after installation.

Photo: Johns Manville

Some designers and membrane manufacturers specify the use of cover boards as a means of protecting the insulation. If specified, installers should ensure the cover board used is compatible with all components of the roofing system, is acceptable to the membrane manufacturer, and meets specified fire, wind, and code requirements.

Polyiso roof insulation, like other roofing materials, requires a proper understanding of storage, handling, and application to result in a properly constructed roof system. To find additional information about the proper storage and handling of polyiso insulation and for more technical information on polyiso roof and wall insulation, please visit www.polyiso.org.

Building to Last With Asphalt-Based Roofing

The property owner of this building opted for a BUR/modified-bitumen hybrid system with reflective white coating. Photos: Johns Manville

The advantages of a built-up roofing (BUR), modified bitumen, or hybrid roofing assembly include long life, a variety of maintenance options, and outstanding puncture resistance. This durability means property owners will spend less time worrying about fixing leaking roofs and the associated hassles — lost productivity, disruption in operations, slips and falls, repair bills, and other liabilities.

Recommending clients install a roof system that gives them the best chance of eliminating unproductive distractions is a good business decision for design/construction professionals. A more durable roof will enable property owners to focus on making profits instead of dealing with the aftermath of a roof leak.

“I have no problem endorsing asphalt-based roofing,” says Luther Mock, RRC, FRCI and founder of building envelope consultants Foursquare Solutions Inc. “The redundancy created by multiple plies of roofing is really what sets systems like BUR and modified bitumen apart.”

One can argue BUR’s closest cousin — the modified bitumen (mod bit) assembly — is actually a built-up roof made on a manufacturing line. The reality is the plies of a BUR create a redundancy that can help mitigate any potential oversights in rooftop workmanship.

BUR systems are offered in a variety of attractive and reflective options with a proven track record of performance. Photos: Johns Manville

“I’ve replaced BURs for clients I worked with 30 years ago,” says Mock. “We recently replaced [a BUR] specified in the early 1980s. And the only reason was because some of the tectum deck panels had fallen out of the assembly. Meanwhile, the roof was still performing well after 30 years.”

According to the Quality Commercial Asphalt Roofing Council of the Asphalt Roofing Manufacturers Association (ARMA), one of the main drivers of the demand for BUR systems is the desire of building owners for long life cycles for their roofs.

“A solid core of building owners and roofing professionals in North America continue to advocate asphalt-based roofing systems because of their long lives,” says Reed Hitchcock, ARMA’s executive director.

Benefits of Asphalt-Based Roofing

Over the years, asphalt-based roofing assemblies have earned a reputation for reliability with building owners, roofing consultants, architects, engineers, and commercial roofing contractors. The original price tag tends to be greater than other low-slope roofing options, but these assemblies offer competitive life-cycle costs. BUR enjoys a track record spanning more than 150 years; it provides a thick, durable roof covering and can be used in a broad range of building waterproofing applications.

An aerial view of a reflective roof membrane. Photos: Johns Manville

Available as part of fire-, wind-, and/or hail-rated systems, BUR and modified bitumen assemblies offer proven waterproofing capabilities, high tensile strength, long-term warranties, and a wide choice of top surfacings (including ‘cool’ options). Their components include the deck, vapor retarder, insulation, membrane, flashings, and surfacing material. The roofing membrane can be made up of a variety of components, including up to four high-strength roofing felts, modified bitumen membranes (hybrid systems) and standard or modified asphalt. Hot-applied asphalt typically serves as the waterproofing agent and adhesive for the system.

The roofing membrane is protected from the elements by a surfacing layer — either a cap sheet, gravel embedded in bitumen, or a coating material. Surfacings can also enhance the roofing system’s fire performance and reflectivity ratings.

Another surfacing option is gravel, commonly used in Canadian applications where the existing roof structure can handle the extra weight. There are also several smooth-surface coating options, the most popular of which are aluminum or clay emulsion products offering greater reflectivity than a smooth, black, non-gravel-surfaced roof. These reflective roof coating options are typically used in warmer regions when required by code. Reflective white roof coatings are also becoming more popular.

Cold-Process BUR

Cold application of BUR has provided an alternative to traditional hot-applied systems for more than 48 years. The term ‘cold-applied’ means the BUR roofing system is assembled using multiple plies of reinforcement applied with a liquid adhesive instead of hot asphalt. These cold adhesives are used between reinforced base/ply sheets to provide a weatherproof membrane.

The owner of this shopping mall chose BUR primarily due to its redundancy. Multiple plies of roofing can provide extra insurance against water intrusion. Photos: Johns Manville

In BUR cold-process roof systems, manufacturers typically require that only fully coated, non-porous felts (such as standard base sheets) are used as base and ply sheets. Generally, an aggregate surfacing or a coating is then applied over the completed membrane to provide surface protection and a fire rating for the roof system.

“In the re-roofing market, we’re definitely seeing more cold-applied systems being specified, particularly with modified bitumen,” says Mock. “It’s a natural alternative when a building may be occupied during the reroofing process and hot asphalt is not an option.”

Adhesives can be manually applied with a squeegee, brush, or spray application equipment. When numerous roof penetrations or rooftop access become issues, manual application of adhesives is usually the best option. Proper coverage rates are vital to a successful, long-term, cold-applied roof system. Both spray and manual application methods require the proper amount of adhesive material be installed. If too little adhesive is applied, there is a potential for an improper bond to be formed between the felts. If too much is applied, then the potential for longer setup times and membrane slippage is increased. Additionally, ambient temperatures must be 40 degrees Fahrenheit (5°C) and rising before installation. This limits, but does not preclude, use of cold-process BUR in much of the northern United States and Canada.

“I’m also comfortable specifying BUR, because I’m confident I will have a seasoned contractor on the job,” says Mock. “The commitment in terms of skilled labor and equipment is simply too great for these contractors to be first-timers.”

Flashings are another critical component of every roofing system, particularly in cold-weather applications. Four-ply BURs use modified bitumen flashings almost exclusively. These membranes are predominantly styrene butadiene styrene (SBS)-modified and offer greater elongation in frigid climates where it counts most — at the interface of the roof system with other building components.

Use of a modified-bitumen base ply is one way of handling general flashing requirements, although modified bitumen cap sheets are more common.

BUR Repair and Maintenance

Like all roof systems to some extent, the life expectancy of a BUR system depends on the property owner’s commitment to routine maintenance. All roof systems can benefit from an owner willing to undertake a proactive management plan. BUR installed over an insulation package lends itself well to non-destructive testing in the future (e.g., infrared) as a means to maximize service life.

“Asphalt roofing systems have the potential for a very long life, and preventive maintenance is the key to realizing that potential,” says Hitchcock.

Non-gravel BUR surfacing options include aggregate, a mineral surface cap sheet, or a smooth, surface-coated membrane. Photos: Johns Manville

The goal is for problem areas to be detected and fixed before they develop into leaks. Inspections can reveal potentially troublesome situations, such as a loss of gravel surfacing, which could lead to felt erosion or brittleness. Less commonly, punctures and cuts to the membrane can occur, so it is wise to remove sharp objects and debris from the roof. Clogged drains or poorly sealed flashings also present problems that are repaired easily. The effects of chemical exhausts on roofing materials should also be monitored.

Preventive maintenance actions can help catch problems before they damage larger areas of the roof system. Inspections should be performed not only on aging roofs, but also on newly-installed roofs to guard against errors in installation, design, or specifications.

BUR and modified bitumen also have a long history of proven performance in the northern United States and Canada, where snow and ice buildup are common. Perhaps more than any other roof membrane, the BUR system shrugs off minor abuse.

BUR has proven to be a low-maintenance roofing system, and it can also be effectively repaired when needed. This means property owners can usually get more life out of a BUR. The ability to enhance the performance of existing BUR membranes with coatings, mod bit cap sheets, or flood coats of asphalt explain the long service lives of these systems in demanding applications.

“Property owners rarely have to replace a four-ply BUR until it is absolutely, positively worn out,” says one roofing contractor who asked to remain anonymous. “Based on experience, these asphalt-based systems ‘hang in there’ longer than less-robust roof options.”

When BUR Is Not the Best Option

There is no roofing product solution that will fit every building specification, and that certainly holds true for BUR. Probably more than any other roofing system (except spray polyurethane foam), the built-up roofing application is more of a skill than a science. As alternative systems have been introduced into the market, the job of finding experienced BUR contractors has become more difficult. This is especially true for the hot mopping of multi-ply BUR systems.

BURs are labor intensive and their installed cost will fluctuate with crude oil prices. However, as oil prices have continued to fall, BUR manufacturers have enjoyed the lowest asphalt pricing since the 2008-09 recession. (The price of oil peaked at about $117 a barrel in September 2012 and is $50 a barrel at this writing.) Typically BUR manufacturers will pass on a portion of these savings to their customers.

BUR has always held up well in life-cycle cost analyses. However, if a roof is not expected to last 20 years or more, it usually does not make sense to specify a premium four-ply BUR.

On larger projects, gravel-surfaced BURs are typically not practical from a cost standpoint unless a source of gravel is available locally. Projects where roof access is difficult often present challenges when roofing kettles are used. And despite the preponderance of low-fuming asphalts and kettles, re-roofing occupied buildings is often unacceptable to neighbors and/or the property owner.

Built-up roofing systems have sufficient strength to resist normal expansion and contraction forces that are exerted on a roof; however, they typically have a low ability to accommodate excessive building or substrate movement. Rephrased, if the roof must be used to “hold the walls” together or if the use of “loose-laid insulation” has a benefit, then a traditional three- or four-ply built-up roofing system is not a good choice.

A built-up roof typically provides high tensile strength with low elongation. Guidelines about where expansion joints should be installed in the roofing system should not be ignored by the designer. These guidelines include installing expansion joints where the deck changes direction, approximately every 200 feet (61 meters), although many consider that this dimension can be expanded for single-ply roofing membranes; where there is a change in deck material; and, anywhere there is a structural expansion joint, etc. Based on these requirements, on some projects it simply isn’t practical to use a BUR.

BUR materials must be kept dry before and during installation to prevent blistering in the roof system. Proper storage is the key: Do not overstock the roof; use breathable tarps to cover material on the roof; store material on pallets to minimize the possibility of material sitting in water; and store rolls on-end to prevent crushing. In general, polymeric single-ply membranes like TPO (thermoplastic polyolefin) are less susceptible to storage issues.

Many roof consultants and product manufacturers clearly state that there should be no phased construction of a built-up roof. If phasing is required, then a BUR should not be specified. This is a clean and simple rule to understand; if the roof being constructed is a four-ply BUR, then only as much insulation should be installed as can be covered the same day with all four of the plies in the built-up roofing membrane. Phased construction of a built-up roof greatly increases the potential for blistering of the membrane and does not allow for the total number of plies to be installed in a shingled fashion. Phased application contains other perils, such as roofing over a small amount of overnight precipitation or dew that, even with the best of intentions, can cause harm.

As stated above, costlier modified bitumen materials should be specified for flashings and to strip in metal. Stripping in two plies of felt will most likely result in splitting at the joints in a gravel stop because the two-ply application cannot accommodate the movement in the edge metal. On new or existing buildings where significant expansion/contraction is expected, a TPO, PVC or EPDM roof membrane can save the property owners money and eliminate premature roof failure due to roof splitting.

Conclusion

Manufacturers across North America are making asphalt roofing systems like BUR better and more versatile for architects, builders, contractors, roofing consultants, and building owner/managers. Thanks especially to the addition of polymers that add stretch and strength, architects can now specify a commercial, low-slope roof as part of a multi-ply BUR system any way they want it — hot, cold, torch, or self-adhered (hybrid BUR) — to meet the individual low-slope roofing project’s needs.

Most importantly, asphalt-based roofing products offer exceptional life-cycle cost performance. They have proven to be reliable, easy to maintain, and are trusted to perform exceptionally well in extreme weather conditions.

SPRI Updates and Improves Roof Edge Standards

Low-slope metal perimeter edge details, including fascia, coping and gutters, are critical systems that can strongly impact the long-term performance of single-ply roofs. Photo: Johns Manville

The effect of high winds on roofs is a complex phenomenon, and inadequate wind uplift design is a common factor in roofing failures. Damage from wind events has historically been dramatic, and wind-induced roof failure is one of the major contributors to insurance claims.

Roofing professionals have long recognized the importance of proper low-slope roof edge and gutter designs, particularly in high-wind conditions. For this reason, SPRI, the association representing sheet membrane and component suppliers to the commercial roofing industry, has spent more than a decade enhancing testing and design standards for these roofing details.

SPRI introduced the first version of its landmark standard, ANSI/SPRI/ES-1 “Wind Design Standard for Edge Systems Used with Low Slope Roofing Systems” in 1998. Since then, the association has continually revised, re-designated and re-approved the document as an ANSI (American National Standards Institute) standard.

Testing of edge securement per ANSI/SPRI ES-1 is required per the International Building Code (IBC), which has been adopted by every state in the country.

This standard provides the basic requirements for wind-load resistance design and testing for roof-edge securement, perimeter edge systems, and nailers. It also provides minimum edge system material thicknesses that lead to satisfactory flatness, and designs to minimize corrosion.

Construction professionals have been successfully using the standard, along with the specifications and requirements of roofing membrane and edge system manufacturers to strengthen their wind designs.

Until recently, the biggest news on the wind design front was the approval of ANSI/SPRI/FM 4435/ES-1, “Wind Design Standard for Edge Systems Used with Low-slope Roofing Systems.” Let’s call it “4435/ES-1” for short. SPRI knew recent post-hurricane investigations by the Roofing Industry Committee on Weather Issues (RICOWI) and investigations of losses by FM Global consistently showed that, in many cases, damage to a low-slope roof system during high-wind events begins when the edge of the assembly becomes disengaged from the building. Once this occurs, the components of the roof system (membrane, insulation, etc.) are exposed. Damage then propagates across the entire roof system by peeling of the roof membrane, insulation, or a combination of the two.

Recognizing that edge metal is a leading cause of roof failures, SPRI has redoubled its efforts to create a series of new and revised documents for ANSI approval. As has always been the case, ANSI endorsement is a critical step toward the ultimate goal of getting these design criteria included in the IBC.

A Systems Approach to Enhancing Roof Edge Design

Roofing professionals understand that successful roof design requires the proper integration of a wide variety of roofing materials and components. For years, leading roofing manufacturers have taken a “systems” approach to their product lines. Recently, SPRI has zeroed in on the roof edge. Low-slope, metal perimeter edge details include fascia, coping and gutters, are critical systems that can strongly impact the long-term performance of single-ply roofs.

As part of the ES-1 testing protocol, RE-3 tests upward and outward simultaneous pull of a horizontal and vertical flanges of a parapet coping cap. Photo: OMG Edge Systems

SPRI first addressed roof gutters in 2010 with the development of ANSI/SPRI GD-1. The testing component of this document was recently separated out to create a test standard and a design standard. The test standard, GT-1, “Test Standard for Gutter Systems,” which was approved as an American National Standard on May 25, 2016.

Similarly, SPRI has revised 4435/ES-1 to only be a test standard.

Making both edge standards (4435/ES-1 and GT-1) into standalone testing documents makes it easier for designers, contractors and building code officials to reference the testing requirements needed for metal roof edge systems.

IBC requires that perimeter edge metal fascia and coping (excluding gutters), be tested per the three test methods, referred to as RE-1, RE-2 and RE-3 in the ES-1 standard. The design elements of ES-1 were never referenced in code, which caused some confusion as to how ES-1 was to be applied. The latest version of 4435/ES-1 (2017) only includes the tests referenced in code to eliminate that confusion.

Test methods in 4435/ES-1 2017 have the same names (RE-1, RE-2, and RE-3), and use the same test method as 4435/ES-1 2011. Because there are no changes to the test methods, any edge system tested to the 2011 version would not need to be retested using the 2017 version.

FM Global’s input was instrumental in the changes in 2011 when ANSI/SPRI ES-1 incorporated components of FM 4435 to become 4435/ES-1. However, there are no additional FM related changes in the latest 4435/ES-1 standard.

This gravel stop is being tested according to the ANSI/SPRI ES-1 standard using the RE-2 test for fascia systems. Photo: OMG Edge Systems

Per ANSI requirements, 4435/ES-1 2011 needed to be re-balloted, which is required by ANSI every five years. SPRI took this opportunity to have it approved as a test standard only to eliminate the confusion referenced above. FM Global was consulted and indicated it wanted to keep “FM” in the title. (FM was on the canvas list for the test standard and actually uses it as its own test standard.)

With 4435/ES-1 becoming a test standard for coping and fascia only, and GT-1 being a test standard for gutters, SPRI determined that a separate edge design standard was needed. Meet ED-1, a design standard for metal perimeter edge systems.

The design portions of the ES-1 edge and the GD-1 gutter standards have been combined and are now referenced by SPRI as ED-1. It has been developed and is currently being canvassed as an ANSI standard that will provide guidance for designing all perimeter edge metal including fascia, coping, and gutters.

ED-1 will be canvassed per the ANSI process later this year. However, SPRI is not planning to submit ED-1 for code approval.

SPRI ED-1 will include:

Material Design

  • Nailer attachment
  • Proper coverage
  • Recommended material thicknesses
  • Galvanic compatibility
  • Thermal movement
  • Testing requirements
  • “Appliance” attachment to edge systems

Limited Wind Design

  • Load to be required by the Authorities Having Jurisdiction (AHJ).
  • Tables similar to those included in 4435/ES-1 will be included for reference.

If this sounds a tad complex, imagine the design work required by the dedicated members of SPRI’s various subcommittees.

The Test Methods in Detail

The GT-1 standard is the newest, so let’s tackle this one first. As noted above, the ANSI/SPRI GT-1 test standard was developed by SPRI and received ANSI Approval in May of 2016. Testing of roof gutters is not currently required by IBC; however, field observations of numerous gutter failures in moderate to high winds, along with investigations by RICOWI following hurricanes have shown that improperly designed or installed gutters frequently fail in high wind events. GT-1 provides a test method that can be used by manufacturers of gutters, including contractors that brake or roll-form gutters, to determine if the gutter will resist wind design loads. Installing gutters tested to resist anticipated wind forces can give contractors peace of mind, and may provide a competitive advantage when presented to the building owner.

This gutter is being tested using the test method specified in ANSI/SPRI GD-1, “Design Standard for Gutter Systems Used with Low-Slope Roofs.” Photo: OMG Edge Systems

GT-1 tests full size and length samples (maximum 12 feet 0 inches) of gutter with brackets, straps, and fasteners installed per the gutter design. It is critical that the gutter be installed with the same brackets, straps, and fasteners, at the same spacing and locations as per the tested design to assure the gutter will perform in the field as tested. The fabricator should also label the gutter and/or provide documentation that the gutter system has been tested per GT-1 to resist the design loads required.

GT-1 consists primarily of three test methods (G-1, G-2, and G-3). Test method G-1 tests the resistance to wind loads acting outwardly on the face of the gutter, and G-2 tests the resistance to wind loads acting upwardly on the bottom of the gutter. G-3 tests resistance to the loads of ice and water acting downwardly on the bottom of the gutter.

Tests G-1 and G-2 are cycled (load, relax, increase load) tests to failure in both the original GD-1 standard and the new GT-1. The only change being that in GD-1 the loads are increased in increments of 10 lbf/ft2 (pound force per square foot) from 0 to failure, and in GT-1 they are increased in increments of 15 lbs/lf (pounds per linear foot) from 0 to 60 lbs/lf, then in 5 lbs/lf increments from above 60 lbs/lf to failure.

Note also that the units changed from lbf/ft2 (pound force per square foot) to lbs/lf (pounds per linear foot), which was done so that the tests could be run using the test apparatus loads without having to convert to pressures.

The GT-1 standard specifies a laboratory method for static testing external gutters. However, testing of gutters with a circular cross-section is not addressed in the standard, nor does the standard address water removal or the water-carrying capability of the gutter. In addition, downspouts and leaders are not included in the scope of the standard.

SPRI intends to submit ANSI/SPRI GT-1 for adoption in the next IBC code cycle.

As referenced above, IBC requires that perimeter edge metal (fascia and coping), excluding gutters, be tested per three test methods, referred to as RE-1, RE-2 and RE-3 in the ES-1 standard.

RE-1 tests the ability of the edge to secure a billowing membrane, and is only required for mechanically attached or ballasted membrane roof systems when there is no peel stop (seam plate or fasteners within 12 inches of the roof edge). RE-2 tests the outward pull for the horizontal face of an edge device. RE-3 tests upward and outward simultaneous pull on the horizontal and vertical sides of a parapet coping cap.

Calculating Roof Edge Design Pressures

All versions of ANSI/SPRI ES-1 and ANSI/SPRI GD-1, the 2011 version of ANSI/SPRI 4435/ES-1, and the new ED-1 standard all provide design information for calculating roof edge design pressures. These design calculations are based on ASCE7 (2005 and earlier), and consider the wind speed, building height, building exposure (terrain), and building use.

A gravel stop failure observed during roof inspections after Hurricane Ike in Sept. 2008. Photo: OMG Edge Systems

However, as stated above, IBC requires that the load calculation be per Chapter 16 of code, so the SPRI design standards are intended only as a reference for designers, fabricators, and installers of metal roof edge systems.

ES-1-tested edge metal is currently available from pre-manufactured suppliers, membrane manufacturers and metal fabricators that have tested their products at an approved laboratory.

The roofing contractor can also shop-fabricate edge metal, as long as the final product is tested by an approved testing service. The National Roofing Contractors Association (NRCA) has performed lab testing and maintains a certification listing for specific edge metal flashings using Intertek Testing Services, N.A. Visit www. nrca.net/rp/technical/details/files/its details.pdf for further details.

A list of shop fabricators that have obtained a sub-listing from NRCA to fabricate the tested edge metal products are also available at www. nrca.net/rp/technical/details/files/its details/authfab.aspx.

SPRI Continues to Take Lead Role in Wind Testing

As far back as 1998, SPRI broke ground with its ANSI/SPRI/ES-1 document addressing design and testing of low-slope perimeter edge metal. Today, the trade association has a variety of design documents at the roofing professional’s disposal, and is working to get ED-1 approved as an Edge Design Standard to be used for low-slope metal perimeter edge components that include fascia, coping and gutters.

All current and previously approved ANSI/SPRI standards can be accessed directly by visiting https://www.spri.org/publications/policy.htm.

For more information about SPRI and its activities, visit www.spri.org or contact the association at info@spri.org.

Steep-Slope Projects: Risks, Considerations and Best Practices for Contractors

Photos: Atlas Roofing

Photos: Atlas Roofing

Many contractors treat residential roofing as routine. However, whether a re-roof or new construction, each project can be infinitely complex and should be addressed as such by always accounting for weather and safety issues, as well as proper installation and customer service.

One of the most prominent and popular elements of residential architecture is a steep-slope roof. According to the Occupational Safety and Health Administration (OSHA), steep-slope roofs have slopes greater than 4:12 and range from 18.5 degrees to 45 degrees or more. While the process of installing a roof with these angles isn’t necessarily much different from a low-slope roof, it can pose more risks and considerations for workers.

Weather Woes

Weather plays an important role in every roofing project, but staying on top of potential issues from Mother Nature is especially crucial during steep-slope jobs.

Photos: Atlas Roofing

Photos: Atlas Roofing

In high temperatures, workers may fall victim to heat cramps, heat exhaustion, heatstroke or worse. The best way to beat the heat is to start early and get as much done as possible before the temperature peaks. Starting early in the summer—specifically in the South—can allow work to be completed before daily rain showers roll in. Proper hydration and attire are also important.

Cold temperatures can create even more complications because some manufacturers advise against installing their products in weather below 45 degrees Fahrenheit and certain equipment is susceptible to freezing. Furthermore, workers have to pay extra attention to the grip of their shoes to avoid slipping and falling. Not to mention, freezing-cold hands and feet may cause an otherwise adept worker to become clumsy. Wearing the proper clothing is key during cold-weather jobs, and workers should be advised to keep an eye out for the first signs of frostbite, including cold skin, redness, tingling and numbness.

Safety Considerations

In 2015, falls were the leading cause of private-sector work deaths in the construction industry, accounting for nearly 40 percent of worker fatalities, according to OSHA. In addition, OSHA reports nearly 90 percent of fatal falls happen due to the lack of a fall-protection system.

Photos: Atlas Roofing

Photos: Atlas Roofing

When working on a roof slope greater than 4/12, OSHA requires additional safety measures, which include either a guardrail system with toeboards, safety net systems or personal fall arrest systems. Yet, many contractors—especially residential roofers—choose to forgo protective devices because they feel they are not feasible or create a greater hazard. In such cases, OSHA does allow the use of alternative fall-protection methods in residential construction, as long as contractors develop a written, job-specific fall-protection plan that complies with OSHA regulations.

Proper Installation

During the installation process, roofers should keep a few things in mind whether they’re applying shingles to a steep-slope or low-slope structure.

  • Valleys
Photos: Atlas Roofing

Photos: Atlas Roofing

Valleys are a critical part of proper roof installation because they experience the most water flow during rainstorms and can be potential leak points.

In an open valley, a piece of aluminum, copper or other type of metal is used to help keep rainwater flowing off the roof. Open valleys are often used when a homeowner wants a showier look, such as on a Colonial-style home.

Closed valleys—the most common valley installation method—use asphalt shingles and offer a more traditional look. When properly installed, they keep water from getting trapped in the valley and allow for proper drainage.

In addition to open and closed valleys, contractors also have the option to create a weave valley, which alternates shingles through the valley from both sides, creating a braid-like effect.

Laminate/architectural shingles should not be used for weave valleys. Because laminate shingles aren’t one-dimensional, they do not create the flat surface needed for a weave valley, which should only be used with three-tab shingles.

When using laminate shingles, be sure to follow instructions on the wrapper for either an open or closed application.

Contractors also need to be extremely careful around obstacles such as chimneys and skylights, which require their own flashing and water divergence methods. For instance, more flashing may be needed in these areas to divert water and prevent leaks.

  • Starter Shingles

Starter shingles allow the first course of shingles to properly seal down, protecting the edge of the roof and providing anchoring power for high-wind resistance at the critical eave and rake areas. They further protect the roof by filling in spaces under the cutouts and edges for the first course of exposed shingles, preventing wind uplift.

Photos: Atlas Roofing

Photos: Atlas Roofing

The most common mistake when installing starter shingles or modifying traditional three-tab shingles is putting them on backward or upside-down.

Additionally, the overhang should be no more than three-quarters of an inch to prevent wind from penetrating beneath shingles, as well as to keep shingles from curling or cracking.

In addition, many manufacturers caution against double-stacking pallets of starter shingles, which can cause the bottom shingles to warp. Be sure to read all storage and handling instructions prior to installation.

  • Underlayment

Underlayment is an important part of the roofing process and is required by code for residential properties to meet Class A fire requirements. Serving as a secondary barrier, underlayment protects rakes, eaves and critical flashings from water infiltration. Most warranties also require underlayment for the roof to be ASTM compliant. However, some contractors still opt not to use it because they want to save time on a project or their customer balks at the cost.

Photos: Atlas Roofing

Photos: Atlas Roofing

Another frequent error during underlayment installation is incorrect overlaps. On low-slope roofs (slopes between 2:12 and 4:12), underlayment should have double coverage. And while traditional installation is fine on steep-slope roofs, always follow manufacturer instructions for overlaps from course to course.

Last but not least, be sure to keep underlayment from wrinkling, which can cause ripples in the shingles. While trying to keep underlayment as flat as possible, avoid pulling it too tight because it has a natural expansion and contraction. If underlayment gets wet, be sure it adequately dries out before continuing the installation process.

  • Shingles and Nails

Shingles should be installed with the manufacturer’s recommended offset, which will help prevent leak points and also properly align the shingles across the roof. Once all of the shingles are aligned, only the shingles themselves should be exposed—not the nails.

Because the common bond area is the strongest part of a shingle, manufacturers require nails be placed there to achieve the advertised wind performance. Nails should not be too high or too low, or unevenly spaced. If nails aren’t positioned correctly, the manufacturer’s wind warranty may not be valid.

Customer Service Follow-Up

Providing excellent customer service is key to every roofing job. Homeowners who have a good experience are more likely to share positive reviews and opinions.

Photos: Atlas Roofing

Photos: Atlas Roofing

Before starting a steep-slope project, be sure to discuss the entire process with homeowners to ensure that they know what to expect, as well as the types of warranties they will receive with their new roof. In addition, prepare the surrounding property, such as windows and landscaping, to prevent damage during the installation process.

During the job, be sure workers are vigilant about not dropping nails anywhere on the jobsite. After the job, walk the property with the homeowners to ensure all debris and materials were cleaned up; magnets can be used to double-check for stray nails. If the homeowners are happy with the finished product and their experience, don’t be afraid to ask them to write a nice review on the company website, Angie’s List, Yelp or other customer referral app.

Most of the best practices for steep-slope roofing can be applied to any type of roofing project. However, steep-slope work can pose additional challenges that other projects may not. Always follow manufacturer’s instructions and OSHA guidelines on all roofing jobs, but especially on steep-slope projects, when one minor slip could turn into major consequences for all involved.

About the Author: Paul Casseri is the product manager of the Roofing Shingles and Underlayment Division for Atlas Roofing Corp., www.atlasroofing.com. He is responsible for all areas of product management, including product initiation, feasibility, design, development and testing. He is a graduate of Penn State University with more than 20 years of experience in the building products industry.