Why Seals Fail and What To Do About It


Light leaks, sound leaks, water leaks… Even small leaks compromise the integrity of a window or door with consequences ranging from a higher energy bill to catastrophic water damage. Leaks, of course, occur when a gap forms between the gasket and the frame, and there are many ways this can happen. 

Sometimes, the gasket has shrunk due to age. Every seal will eventually show signs of aging, though some materials like PVC will exhibit the symptoms sooner than others. Old seals will crack and grow stiff, creating vulnerabilities. 

Thermal cycling speeds the aging process. Certain thermosets and other elastomers are particularly sensitive to thermal stresses and will warp and pull away from the frame when subject to extreme temperatures. Natural rubber, such as silicone, or a thermoplastic elastomer, such as TPV, are preferable choices in systems that are subject to extreme temperatures. It is important to consider the environment of the application when choosing the proper material for a door seal. 

Even the sturdiest seal that can weather all temperatures may allow gaps to form as the frame itself moves and warps. Whether using EPDM, PVC, or TPV, manufacturers must consider the compression set and durometer of the seal. When the frame inevitably shifts, the seal may need to withstand greater compression (in cases where the gap has gotten smaller), or may need to expand to fill a wider gap. 

It's an Eyesore

For luxury commercial and residential buildings in particular, aesthetic failure can be as costly to business as performance failure. The visual focus should be the architecture, not the gaskets. While a quality seal provides a luxe contour at its most visible, a failed seal is obtrusive and ugly. 

Old seals made from cheap material will appear dry and shriveled. Exposure to sunlight and moisture can fade and stain colors. Warped gaskets pull away from the frame and become conspicuous blemishes that ruin a clean, professional aesthetic. 

 Window and door manufacturers should request a thorough design review from the seal manufacturer before gasket extrusion. A proper examination of a system and application environment will help to produce a seal that will look new for as long as possible.


Complete Failure


Building owners will sometimes ignore a slight thermal leak or a hidden water stain on a seal, but some problems demand immediate attention. A window can irreparably crush a gasket with poor design. Improper installation, cheap material, and weak adhesion can all lead to potential damage and costly repairs. 

A door seal is like a pinky toe. It’s out of sight out, out of mind… until it breaks. That’s why Reed Rubber Products engages in a careful design review process with all our projects. We ask thorough questions and review every detail to ensure that our customers’ customers don’t even think once about window or door seals. 


The best designed seal can look shabby in five years if the material is not perfectly suited to the application. There is no one-size-fits-all solution for window or door seals. TPV, PVC, and EPDM are all frequently used materials for extruded seals, and it is important to discuss the specific application with a trusted seal supplier to ensure that you have the best material for your system. PVC is often chosen for easy color-matching but is considered a poor choice if the application is going to be exposed to temperature extremes. Warm temperatures will accelerate aging in PVC and may lead to warping within the channel. EPDM is a popular cost-effective choice with good elasticity but will generally age at an expedited rate in cold temperatures.

See the results of a heat aging test comparing PVC and TPV