How can you prevent leakage and water intrusion into your exposed-fastened roof?

Holes in your roof need to be sealed, but externally applied sealants and sealants will eventually dry out and crack, causing leakage and corrosion. When installing solar panels, HVAC, snow skirts, satellite dishes, and other accessories, you must penetrate EF roofs so that the sealants you use critical prevent roof leakage. Let’s take a look at how selecting EPDM and butyl sealants in the right applications will protect your roof.

Poor and messy externally applied sealant and sealant on a visible fastened metal roof

What makes EPDM and butyl sealants so effective?

Here is a brief overview of their features:

  • EPDM (ethylene propylene diene monomer) is a smooth, semi-hard, synthetic rubber with high tensile strength, flexibility, long life, reliability in hot and cold climates and moisture resistance. EPDM is so waterproof; it is even used as a pond liner.
  • Butyl Tape Sealant (a copolymer of isobutylene with isoprene) is an airtight, watertight adhesive rubber that forms an impermeable moisture barrier. Uncured and tacky, butyl remains flexible even at extreme temperatures. a study shows that butyl tape is still elastic and pliable after 33 years and is estimated to last 60+ years.

Excellent elasticity demonstrated by the butyl sealant on a metal roof in Denver, Colo. after 33 years of use.

How can you extend the life of EPDM and butyl tape sealant?

As with almost anything, the specific formulations of these types of sealants vary from manufacturer to manufacturer. Their individual formulations are patented and create their own ‘secret sauce’. In other words, they don’t all perform the same. This makes it necessary to buy from a supplier with a long history of success.

In addition to choosing a supplier of known integrity, the life of both EPDM and butyl tapes can be extended in two ways to ensure their best performance over time:

  • Do not use sealant as a surface applied fix on a roof. Chemistry of sealants is complicated. If kittens are not properly protected, multiple factors can break down their chemical bonds. Surface applications are subject to degradation from UV, ozone, mechanical wear, dirt and other contaminants. Application as a gasket material will help protect sealants against these threats. But even when used as gasket material, the best sealants can still have vulnerabilities. Look for fittings where the sealant will be hidden from exposure and even protected at the edges if possible.
  • Avoid overcompression. Tighter is not better in this case. When turning the screw, tighten it, but do not overtighten it. Otherwise, you could dilute and move the gasket material, reducing its life and effectiveness. Best practice is to use a part design with a built-in “reservoir” to encapsulate the material and help prevent overcompression.

Where is the best place to use EPDM versus butyl when assembling your fittings?

Geographical locations or “roof culture” influence mounting preferences. Fixing in the flat of the panel (the low valley of your wave or the flat area between trapezoidal ribs) is common in the US. In other roof cultures, the penetration is in the higher point of the profile, away from the drainage surface (in the rib).

“Top-fix” – EPDM is a top choice when mounting in the high (in the rib)

Since EPDM is semi-rigid (like gasket material), it must be attached to a flat, level surface to create a watertight joint. The smooth rib of your EF roof profile fits perfectly with EPDM.

“Bottom-Fix” – When mounted in the layer (valley), butyl sealant is ideal.

Butyl’s flexible nature allows it to adapt to the irregular surfaces (small ribs and stripes) in the panel valley. By using butyl tape, the sticky sealant retains its shape and is therefore easy to apply. When mounting in the storey, use only products designed to be secured through the roof sheet into the structure or deck – never only on the plate – to ensure stability, weather resistance and roof protection.

EPDM and butyl are top sealants on the market. Here’s a summary:

  • Use products with factory applied sealants.
  • Select parts designed to protect sealants from: overcompression, UV and environmental pollution.
  • Use EPDM when confirming in height of the rib and butyl in the low.

Learn more how to use EPDM and butyl sealants to prevent roof leaks and protect the life of your EF roof.

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