How to repair metal roof leaks

What Causes Metal Roof Leaks?

Although durable, metal roofs can let in water. The most common place where this occurs is not on the metal panels but rather on the seams and flashing keeping them together.

Understanding where you should look for leaks will save you lots of time and headaches, so let's get into more detail.

Metal Roofing Screws

One of the most common causes of metal roof systems leaks is the screws.

The screws squeeze rubber washers and thus create a gasket keeping the water out. While screwing in a metal panel might seem easy, it actually involves some finesse. You can easily mess things up by underdriving, overdriving, or driving screws at an incorrect angle or even miss the metal roof panel frame entirely.

Here are some of the most common reasons why screws start letting in water:

Wear And Tear

Even if the screws are driven correctly, they can steal wear out over time. The rubber gaskets will dry out and weaken over time, providing a way for water to get under.

overdriven metal roofing screws

Screws often overdrive into the metal panel to ensure a tight seal between the screw head and the panel. However, this can cause the panel to warp around the screw hole and the rubber washer to break due to increased tension.

under driven metal roofing screws

If screws aren't driven all the way into the metal roofing material so that they're flush, they won't form a good seal - which will lead to leaks.

Metal roofing screws driven under a wrong angle

If the screw is driven under an incorrect angle, the rubber washer won't lay flat. This results in a shoddy seal that will let water in.

Degraded Stack Flashing

Whenever you have a stack or vent protruding though the roof, you need to place a flashing around it.

Flashing is a rubberized material used to coat the said vents and stacks so the water doesn't get under the roofing system.

Unfortunately, the flashing isn't as durable as the metal roof and will slowly degrade over time. In most cases, the flashing lasts around half as much as the roof.

If you notice there are any water streaks coming down your stack or vents, there's a good chance you have a problem with degraded flashing.

Missing Sealant

During the roof installation, metal roof sealants are used to waterproof the parts of the assembly. But, just like the flashing, these sealants aren't as durable as the metal roof panels.

This is why sealants have to be reapplied every couple of years. While you can do this yourself, you should leave this to the professionals since you can easily miss parts that need metal roof sealant applied.

Leaky Curb Flashing

Installing an HVAC system on a metal roof is a common practice. In most cases, the HVAC is mounted on top of a roof curb - a metal construction specially designed to hold the unit and provide a way to link it to the air vents.

And, since roof curbs have flashing around them, it will degrade over time and let cause a leak.

Leaky Seams

A metal roof's gaps and overlaps must be properly sealed during installation to prevent leaks caused by capillary action.

Over time, rubber or mastic seals deteriorate due to weather conditions, allowing water to flow and resist gravity in small crevices between roof panels due to surface tension and adhesion forces.

What Causes Metal Roof Leaks?

Although durable, metal roofs can let in water. The most common place where this occurs is not on the metal panels but rather on the seams and flashing keeping them together.

Understanding where you should look for leaks will save you lots of time and headaches, so let's get into more detail.

Metal Roofing Screws

One of the most common causes of metal roof systems leaks is the screws.

The screws squeeze rubber washers and thus create a gasket keeping the water out. While screwing in a metal panel might seem easy, it actually involves some finesse. You can easily mess things up by underdriving, overdriving, or driving screws at an incorrect angle or even miss the metal roof panel frame entirely.

Here are some of the most common reasons why screws start letting in water:

Wear And Tear

Even if the screws are driven correctly, they can steal wear out over time. The rubber gaskets will dry out and weaken over time, providing a way for water to get under.

overdriven metal roofing screws

Screws often overdrive into the metal panel to ensure a tight seal between the screw head and the panel. However, this can cause the panel to warp around the screw hole and the rubber washer to break due to increased tension.

under driven metal roofing screws

If screws aren't driven all the way into the metal roofing material so that they're flush, they won't form a good seal - which will lead to leaks.

Metal roofing screws driven under a wrong angle

If the screw is driven under an incorrect angle, the rubber washer won't lay flat. This results in a shoddy seal that will let water in.

Degraded Stack Flashing

Whenever you have a stack or vent protruding though the roof, you need to place a flashing around it.

Flashing is a rubberized material used to coat the said vents and stacks so the water doesn't get under the roofing system.

Unfortunately, the flashing isn't as durable as the metal roof and will slowly degrade over time. In most cases, the flashing lasts around half as much as the roof.

If you notice there are any water streaks coming down your stack or vents, there's a good chance you have a problem with degraded flashing.

Missing Sealant

During the roof installation, metal roof sealants are used to waterproof the parts of the assembly. But, just like the flashing, these sealants aren't as durable as the metal roof panels.

This is why sealants have to be reapplied every couple of years. While you can do this yourself, you should leave this to the professionals since you can easily miss parts that need metal roof sealant applied.

Leaky Curb Flashing

Installing an HVAC system on a metal roof is a common practice. In most cases, the HVAC is mounted on top of a roof curb - a metal construction specially designed to hold the unit and provide a way to link it to the air vents.

And, since roof curbs have flashing around them, it will degrade over time and let cause a leak.

Leaky Seams

A metal roof's gaps and overlaps must be properly sealed during installation to prevent leaks caused by capillary action.

Over time, rubber or mastic seals deteriorate due to weather conditions, allowing water to flow and resist gravity in small crevices between roof panels due to surface tension and adhesion forces.

How To Repair A Leaking Metal Roof?

Now that you know what are the main causes of metal roof leaks, let's take see how you can fix a leak.

Before we get into the steps, let's go over what tools and materials you'll need:

• Ladders
• A nail bar and a hammer
• A handful of screws and nails
• A drill
• A wire brush
• A putty knife
• A caulk gun
• Metal-roofing base coat paint and a paintbrush
• Scissors
• Butyl tape

Once you have all the tools and materials in place, it's time to get your hands dirty.

Clean The Leaky Area

First, thoroughly clean the roof surface, especially if the issue is caused by rust. Use a specialized metal roof cleaner to remove all dirt, rust, film, or algae from the panels. Afterward, make sure to wipe away any cleaner residue with a wet cloth to ensure a high-quality roof repair.

Scuff The Metal Panels

Next, utilize a wire brush to lightly scuff the metal surface, specifically at the repair area. Scuffing aids in promoting a strong bond with the sealant.

Be cautious to only scuff the necessary area and avoid brushing beyond the repair site to prevent inadvertent removal of the protective coating, which could lead to future deterioration.

Measure Out And Cut A Patch

Now, you need to measure the repair area and cut a metal panel that's around the same size. It should overall the existing metal panels by at least two inches.

Once you've cut a metal patch, don't forget to file the edges. This will prevent won't and ice forming on them.

Next, place the patch over the hole and use a pencil and mark an outline around it. Then, remove the metal patch as see if the outline overlaps other sheets on the roof by at least two inches.

Install The Patch

Once you've made sure the patch is of the right fit, you can start applying sealant to the metal surface.

Follow the outline you've previously drawn and avoid the gaps at the edge. Once you've applied a liberal amount of sealant, press the patch inside it.

Now you need to secure the patch. Use metal screws and make sure they're at least four inches apart and within two inches of the edge of the patch.

The screw should only attach the metal patch to the panel below it.

Paint

Once the sealant has dried off a bit, you can paint the patch so it matches your roof's color.

While preparing a metal roof might seem pretty simple, we recommend you hire a professional to do it for you. This way, you're ensuring you don't cause even more damage.

Whether you have a leaky metal roof or need a full roof replacement - give us a call and schedule a free consultation. Our roofing contractors will give it their all to ensure your roof remains in top condition for years to come.