Blog

Why Metal Roof Leaks?

March 25, 2022

If you've installed metal roofing, you may experience some water leakage from time to time. Proper maintenance is necessary to make them last as possible. That's why I'll tell you why a metal roof leaks and how to prevent it from leaking.

The topics of this article are:

  • What are leaks, and why metal roofs leak?
  • How to prevent leaks?

Let's start with how metal roofing starts leaking?

What Are Leaks and Why Metal Roofs Leak?

Over the years, all types of roofs will experience some sort of leakage, and metal roofs are no different. There can be a multitude of reasons which can cause a leaky roof. An estimated 40% of home damage occurs due to water leakage.

If leakage from a roof isn't stopped, the lifespan of the roof will decrease by half. It means that if a metal roof would last at most 80 years (in good condition), it would be reduced to 40 years.

As you know, metal is a durable material, but it is susceptible to leakage. There can be several reasons for it, and understanding them can extend the life of the roof.  

Reasons for Leaking Metal Roofs

Here are some of the reasons which can cause a metal roof to have a leak.

1. Loose Screws

Metal roofing screws are responsible for the majority of leaks on metal roofs. Roofers seal water out by compressing a rubber washer at the base of the screw head when driving it in the panels, but several things can go wrong, like under-driving or over-driven them.

2. Stack Flashing

The area around stack flashings is often prone to leaks on metal roofs. Stack flushing, also known as "stack boots" or water-proofing for pipes that come out of the rooftop, is designed with a rubberized material.

It sits flat against its surface so it can form both an air-tight seal and also squeeze around any object stuck in between two pieces. The proper installation of it is very important because if not done properly, then it can cause a lot of damage.

The sun's harsh rays are also responsible for shorter lifespans of rubber flushing, according to experts.

3. Lack of Sealants

Metal roof sealants are designed to last as long as possible, but they don't always work perfectly. If you have a metal trim piece like ridge cap or Z flashings on your home's exterior, then these will need replacing at least once every ten years.

Additionally, there could be other components underneath it, such as trims which would require extra attention too. When installing a new metal roof, use the right sealant for your needs.

4. Curb Flashing

Installing HVAC units on metal roofs is a relatively easy process, but it's the flashing that really tests an installer's skill. The small margins for error in this job give little room to make mistakes, and keeping curbs dry can be easier said than done.

Curb appeal is everything, and if you have a high tower HVAC unit, then the uphill side can be challenging to work with because the water often gets trapped behind it and starts leaking out from around your sealants.

5. Overlap and Seams

The problem with seams where two pieces of metal roofing meet each other can be attributed to a condition called a capillary draw. It's when water is able to travel uphill between closely joined surfaces.

In this case, it will cause leaks if left unchecked. To prevent them from happening, you should use sealant or butyl tape on both sides around the perimeter and across any gaps that could allow for liquids (such as rain) passage.

6. Corrosion

The quality of the metal used for roofing is very important. If you are using some cheap material without any water-proof coating, then due to rain, it'll corrode, and leaks may appear.

All of these are some of the reasons which can cause metal roof leaks. Now, let's move to the precautions to take for metal roofs.

How to Prevent Leaks?

For each water leakage issue, different methods are used. All of the fixes are given below:

Screw Fix

Screws can cause different issues, which can lead to leakage. Countering it is very important.

  • Don't overdrive the screw, which can damage the rubber seal.
  • On the other hand, underdriving the screw can cause a gap. Keep it just tight enough.
  • Ensure that the screw is driven straight because screws driven at the wrong angle can create gaps.
  • Don't miss the metal strut or wooden framing because gaps can also appear due to it.

Stack Flashing Fix

Make sure the areas where pipes and vents are coming out have proper stack flashing, and there is no seam or crack.

Sealant Fix

Apply proper sealant and ensure that there are no seams where water can seep into the roof and damage them over time.

Curb Flashing Fix

Just like the stack flashing, make sure that the curb flashing is properly done.

Overlap & Seam Fix

Sometimes there can be overlapping of panels which can create gaps and seems. Proper placement of panels is necessary.

Corrosion FIx

Corrosion is one of the major reasons for leaks in metal roofs. If there isn't proper insulation on the roof it can lead to corrosion. Most of the roofs nowadays have some sort of water resistance but may not.

If your roof doesn't have water resistance, make sure that the layer of water-resistant sheet is applied on the metal roof.

Top Quality Remodeling & Restoration

When an unexpected disaster hits your home or business, you need an honest and dependable company available to help you 24/7.

Get in touch