The Top 5 Issues in Metal Roof Installation

Metal roofs offer a number of benefits for both homeowners and roofing contractors. Installation problems, however, can cause functional or aesthetic issues that can result in problems, delays and unhappy clients. Following are the five most common roof installation issues and how to solve them.

1. Metal Shavings Causing Rust Streaks

Installing a metal roof requires drilling through the aluminum or steel roof panels to attach them to the substrate. The process creates metal shavings, especially at rivet holes along the ridge cap or when drilling through multiple layers of roof panels.

These metal panels show evidence of rust stains caused by metal shavings. Photos: Gulf Coast Supply & Manufacturing

Those tiny shards of metal can cause rust and stains on the roof, as well as corrosion that shortens the lifespan of the roof. The more layers of metal a crew has to drill through, the more shavings will be produced.

“Shavings are no problem when removed quickly,” says Paul Hope, field service technician for Gulf Coast Supply. “It is when they are left behind that they become an issue.”

“When metal shavings sit on the roof for a week to a month they start to corrode,” Hope says. “That corrosion leads to staining of your panels, and that staining leads to unhappy homeowners.”

Roofers should get in the habit of either sweeping or blowing metal shavings off of the roof at the end of the workday, according to Hope.

2. Improperly Installed Underlayment

Underlayment has to be carefully measured and lapped to avoid moisture infiltration into the building envelope. Local building codes specify lap coverage guidelines and slip sheet placement for underlayment installation.

Underlayment must be carefully measured and installed correctly to prevent moisture infiltration. The underlayment shown here is not lapped correctly.

Underlayment is designed to act as a secondary water barrier in case rain makes it past the metal roof. Some of the most common causes of water intrusion are fastener failure, wind-driven rain in extreme storms, or metal-to-metal connections with no sealant.

Avoiding underlayment issues is easy to do if the crew follows installation instructions and code requirements. If underlayment is not installed correctly, however, replacement costs can be expensive and involve removing the metal roof, replacing the roof substrate and installing new underlayment.

3. Over-Tightened and Under-Tightened Fasteners

Proper fastener installation is critical to the efficiency of a roof system. Because fasteners penetrate the metal roof, underlayment and roof deck, they can allow for water infiltration into an otherwise waterproofed roof.

Over-tightened screws compress the washer too much and can cause water to pool. Under-tightened screws will not hold panels securely and can cause premature wear of fasteners and panels.

During the installation, screws must be straight and tight to perform as intended. Fasteners that are not installed straight do not form a proper seal. And even when they are straight, over-tightening the screw compresses the washer too much, forms “dimples” in the metal panel and causes water pooling that can then infiltrate the attic.

Under-tightened screws won’t hold the roof panel securely and can cause premature wear of both the fastener and panel.

4. Inadequate Onsite Storage Arrangements

Roofing materials should be delivered in a particular sequence, close to the time roofers will need them. The longer roofing materials, such as panels, are stored on site, the more prone they will be to damage from the elements or construction-site mishaps.

Improper storage of roofing panels at the jobsite can lead to damaged and corrosion.

Workers should pay attention to where and how materials are stored. Are they out of the way of vehicles? Are they on a flat surface? Are they elevated on one end to allow for drainage of rainwater?

Standing water, especially on unpainted panels, can cause wet storage stains or what is known as “white rust.” Sand, dirt and debris can also damage metal panels, causing permanent stains before they are ever installed on a roof.

5. Delays Due to Worker Injury

Safety is crucial on any jobsite but especially when installing a metal roof. Injury and accident prevention should be the primary duty of crew chiefs and workers alike. Accidents can not only send workers to the hospital, they can affect scheduling and job productivity as well.

“Medical bills, downtime, and loss of skilled laborers for extended periods of recovery can take place,” Hope says. “It is the responsibility of every individual to properly protect themselves from day to day.”

Proper safety equipment is essential. Gloves and Kevlar sleeves can help roofers protect themselves from cuts.

Falls are the most common potential metal roofing injury. Workers should use harnesses when on the roof and in any other fall-risk situations. Someone on the crew also needs to maintain the condition of the safety equipment. “Nicks in the harness can jeopardize your entire fall system,” Hope says.

Cuts caused by the sharp edges of the metal panels are also a hazard. Gloves and Kevlar cut sleeves can help roofers protect themselves.

Less common threats include electrocution and burns. Electricity, whether from a live current or lightning, can travel through the metal. Rubber shoes and gloves can protect roofers from potentially fatal shocks. Burns are less common, but in hot climates, the sun can heat metal enough to cause an injury. Workers can protect themselves with gloves and protective clothing.

Taking care to address these five common metal roofing installation issues can result in a smoother, more effective process, fewer problems and more satisfied clients.

About the author: Jared Pearce is the technical services manager at Gulf Coast Supply & Manufacturing. The son of a general contractor, Pearce has been around the construction industry his whole life. He is also a native Floridian and a Coast Guard veteran. Gulf Coast Supply has been a trusted choice for metal roof products throughout the Southeast for more than two decades. Through its Contractor’s Advantage program, Gulf Coast offers both classroom and hands-on seminars to help fill the industry’s need for qualified roofers. For more information, visit www.GulfCoastSupply.com.