Metal Roof Leak Repair: 5 Options

So, you have a leaking metal roof and you're searching for answers. As a property owner or facilities manager, these kinds of problems can hit hard, causing both operational snafus and unforeseen expenses.

At GIDEON, we're well-versed in metal roof leak repair. With over 20 years of experience in every type of roofing, including metal, we can help you fix these issues and avoid repeating this experience in the future. 

When it comes to repairing leaking metal roofs, you have 5 options: 

1. Finding the leak and sealing it yourself with sealant or tape.
2. Applying a complete elastomeric roof coating
3. Applying a spray foam roof
4. Metal Roof Retrofitting 
5. Complete Replacement

In this article, we’ll discuss these 5 options. We'll also talk about where your metal roof will typically leak and how to find it.

Table of Contents

• Where Do Metal Roofs Usually Leak?

• How to Inspect a Metal Roof For Leaks

• The Best Way to Seal a Leaking Metal Roof Yourself

• Professional Solutions for Metal Roof Leaks (Coatings, Replacements, etc)

Where Do Metal Roofs Usually Leak?

Metal roofs are generally known for their durability and long lifespan, but unfortunately, they’re not invincible.

If you are suffering from a leaky metal roof, here are the areas you’ll want to check out:

Seams and Joints

Metal roofs are made up of multiple metal panels, these panels overlap and are sealed at the seams. These seams or joints are the most vulnerable areas on the roof and are often the first places to develop leaks. Over time, due to expansion and contraction caused by fluctuating temperatures, the seams can become stressed and may start to split or separate, allowing water to seep in.

Roof Flashings

Flashings are materials used to seal roof system edges, perimeters, valleys, and other places where the roof covering terminates. They too are vulnerable to leaks.

Roof Penetrations

Roof penetrations include things like pipes, vents, heat stacks, HVAC units, and skylights. These areas are prone to leaks because they interrupt the continuity of the roof and create opportunities for water entry, particularly if not properly sealed or if the sealant wears out.

Roof Edges

The edges of a metal roof, where it meets the gutter or the wall, can also be a common area for leaks.

HVAC Units or large roof curbs. Water may pond behind these units.

Fastener Holes: Screws and fasteners used to secure the metal roof panels can also be potential sources of leaks. If they become loose or if the washers wear out, water can seep through the holes. Fasteners may also have been installed improperly; they may have been driven in at an angle or overdriven.

Stray Bullets. As surprising as it sounds, it’s not unheard of for stray bullets to fall onto the roof and cause a leak.

Each of these areas presents unique challenges when it comes to preventing and repairing leaks. The subsequent sections will discuss the best ways to address these vulnerabilities and keep your metal roof in good shape.

How to Inspect a Metal Roof For Leaks

Conducting regular inspections is a proactive way to detect potential issues before they become significant problems. Here's how you can inspect a metal roof for leaks:

Examine the Metal Roof Surface

Walk your metal roof and carefully examine the surface. Look for any obvious signs of damage such as separated seams, loose screws, and broken flashings.

Inspect the Flashings

Check all the flashings, such as curb flashings, for damage or signs of wear. Look for any areas where the flashing is loose or has been pushed out of place. When you look at a particular flashing, ask yourself, will it shed water or not? If not, you have an instant problem.

Check Roof Penetrations

Examine the areas around vents, skylights, pipes, and other roof penetrations. Look for any cracks or gaps in the sealant. Look for dark colors along seams. These will show signs of moisture or growth of mold.

Examine the Metal Roofing Screws

Look for loose or missing metal roofing screws. Also, check for worn-out washers that might compromise the seal around the fastener holes. Also look for fasteners that were installed in an angle. In severe cases of expansion and contraction (due to heat), screws may actually back out of the panel and you may find them laying around the roof.

Seek Out Qualified Roofing Experts

If you're unable to identify the source of the leak or if the roof is difficult or dangerous to access, consider hiring a professional roofer. They have the experience and tools necessary to safely and effectively identify and repair leaks.

Remember that it's essential to address any signs of damage as soon as they are discovered to prevent further issues. In the next section, we'll explore the best methods for repairing leaks in a metal roof.

The Best Ways to Seal a Leaking Metal Roof

When it comes to repairing leaks in metal roofs, the industry typically leans on two primary products: sealants and specialized roofing tapes (like butyl tape). The preferred choices are high-solids polyether or silicone sealants.

Seams and Joints: Resealing the seams and joints can often fix the problem. A high-quality sealant is key here. Ensure the area is thoroughly clean before application and apply a generous amount for a complete seal. Where a seam expands or contracts more than 1/8th of an inch, it is absolutely necessary to add polyester fabric to the sealant repair, creating a 3-course layer over the seam that will allow slight movement in the metal roof assembly.

Fasteners: If the leak is due to deteriorated or loose fasteners, consider replacing them. Remove the old fastener, apply a dab of roof sealant in the hole, and install a new, slightly larger screw. It may be necessary to apply a dab of self-leveling roof sealant to the fastener head large enough to encapsulate the entire bolt head and 1/2" surrounding it.

Roof Penetrations: When it comes to roof features like skylights or vents, the best solution is often to reflash the area. Use a flexible, waterproof flashing tape to seal the area around the penetration, making sure to overlap and press firmly to ensure a tight seal.

Flashings: Leaks due to corroded or faulty flashings can usually be resolved by replacing the affected flashing. Ensure that the new flashing is properly sealed with an appropriate sealant and is securely fastened to prevent future leaks. Metal flashings are typically designed to shed water like a cladding system. Sometimes these flashings will not be installed properly or become damaged due to high wind speeds. In some cases, fixing the flashing is as simple as sliding a piece of flat stock metal behind the metal flashing or piece of coping.

If you're unsure or the leak is persistent, consulting with a professional roofer can save time and potentially costly mistakes.

Professional Solutions for Metal Roof Leaks

If traditional methods of sealing and patching do not work, or if the roof is nearing the end of its lifespan, there are several professional solutions that you can consider to address leaks in your metal roof.

Roof Coatings

This is an increasingly popular solution for dealing with roof leaks, due to their tremendous effectiveness. A variety of professional roof  coatings can be applied over the entire surface of the metal roof. These form a seamless, waterproof membrane that can seal leaks and provide additional protection against the elements. Roof coatings not only provide a long-term waterproofing solution, they can also extend the life of the roof by up to 20 years.

Spray Foam Roofing

This involves spraying a layer of polyurethane foam over the entire roof. The foam expands to form a rigid, continuous layer of insulation that not only seals leaks but also provides excellent insulating values.

Metal Roof Retrofitting

Retrofitting involves adding a new roof over the existing one. This not only covers any existing leaks but also adds a new layer of protection for the roof. This is often a cost-effective solution for extensive leaks as it saves on the cost of tear-off and disposal.

Roof Replacement

In cases where the leaks are extensive and the roof is near the end of its lifespan, a complete roof replacement may be the best option. While this is the most costly solution, it provides a fresh start with a new roof that, with proper maintenance, can last for decades.

The Upshot

In this guide, we've dissected metal roofs to their most common trouble spots: seams and joints, flashings, roof penetrations, and fasteners. We've walked through the best ways to locate leaks and fix them, to keep your building dry and your mind at ease.

But remember, you don't have to do this alone. If finding the leak or fixing the issue is proving difficult, that's what we're here for at GIDEON. Contact us for a consultation and let's get your roof back in top shape.