Denver CO Metal Roof Waterproofing: Sealants or Installation?

It's a true nightmare for any Denver CO homeowner: you're seeing leaks pouring from your attic during a strong storm. You're hearing the metal roof pounding, and you're wondering what went wrong with your metal roof waterproofing during installation. In some cases, metal roofing professionals with years of experience in Denver CO will highly advise you to use sealants and tape to fix the leaks.

In fact, Metal Construction News believes that despite all the necessary preparations and design considerations, metal roofers and homeowners should consider using sealants and tape for metal roof leak prevention. Their argument is that no 100% leak-free metal roof waterproofing during installation is possible.

Metal Roof Waterproofing: Sealants and Tapes

For metal roofs, a high-solids polyether or silicone sealant is best. Many of these are pigmented to match popular roof colors so they blend in and form a solid seal. Both of these polymer types have excellent adhesion to metal, including coated metal such as Kynar 500 PVDF, and both are ultraviolet (UV) stable and have excellent weathering and physical properties. Silicone is a little bit better in high temperature zones, especially if a dark, UV-absorbing color is involved.

Roof tapes are also highly effective and efficient to use in repair situations. On a lower slope metal roof, like a 4:1 pitch typically found on large commercial warehouses, leaks form along seams and gaps. A high-quality, watertight roof tape with 30-mil thickness can be easily installed with one worker holding the edge of a 50-foot roll of 4- or 6-inch tape, and another worker walking the roll along the seam or gap, pulling off the backing as the tape is applied. (Continued)

However, some experts believe metal roof waterproofing is possible but just not for all kinds of metal roofs. Corrugated metal roofs are efficient yet affordable. However, metal roof waterproofing is impossible to achieve with it because of one thing: holes in your metal roof.

Unfortunately, these holes are necessary. It is where screws with rubber washers that keep out moisture and rainfall enter and lock your roof in place. However, with the continuous and consistent metal roof contraction and expansion, these wear out. In turn, they become entryway for leaks. Stealth Bond has a great explanation on how this happens.

Metal Roof Waterproofing: Impossible With Screws?

Theoretically, metal roofing screws keep water out by compressing a rubber washer at the base of the screw head against the metal roofing panel. As the screw is driven into the metal roofing panel, the rubber washer effectively becomes a gasket between the roofing panel and the screw. Simple enough, right? Unfortunately, there are a myriad of ways this simple process can go terribly awry.

A properly driven screw is perfectly perpendicular to the panel, is driven straight and with good penetration . When this happens, the rubber gasket is seated firmly against the roof. However, all it takes is one poorly driven screw to make a mess of your attic and your home. (Continued)

Aside from expansion and contraction, metal roof waterproofing with corrugated or exposed-fastener variants is impossible because UV rays can melt the screw washer. In addition, incorrect fastener installation is highly likely especially if you're performing the metal roof installation or replacement by yourself.

Sheffield Metals has a good explanation on UV damage to rubber washers and other materials used for exposed-fastener gaskets below.

Metal Roof Leaks: UV Damage and Fastener Error

  • UV degradation – Another fastener issue is that the gasket is subject to quicker UV degradation than the metal fastener itself. The amount of time that it takes a gasket to degrade from sun exposure varies depending on what material the gasket is made of, such as neoprene, silicone, rubber, or otherwise. This degradation of a fastener’s gasket is the reason why maintenance on an exposed fastener metal roof is vitally important.
  • Incorrect fastener installation – When you have many penetration points and fasteners, there is more of an opportunity for improper installation of a fastener, which is another way for water and air to leak into a structure. Incorrect fastener installation can include:
    • Overdriving the fastener
    • Underdriving the fastener
    • Angling the fastener (Continued)

Metal roof waterproofing might be problematic for corrugated or exposed-fastener roofs. It is for this reason professionals recommend using sealants and tape as an added form of security. In any case, a proper installation done by experts with years of experience and knowledge always lowers the risk of long-term leakage. If you have yet to find a reliable roofer, you can count on Roper Roofing to help. Contact us today to know more about what we can do for you.


795 McIntyre St. Suite 303
Golden, CO 80401

Phone: 720-809-7586



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