Sealing Service Penetrations Airtight and Watertight
Every pipe, cable and duct that passes through the building fabric is a potential air and water leak. Sealing these service penetrations properly is one of the most important — and most skipped — details on site.
Why penetrations leak
Off-the-shelf grommets rarely fit every cable bundle or pipe diameter, and rigid fillers crack around services that move, vibrate or change temperature — opening leak paths over time. Each unsealed penetration is a direct route for air (and often water) through the envelope.
The solution: a liquid grommet
The GOAT Liquid Grommet is a flexible, paint-on sealant that forms a custom airtight and watertight collar around any penetration — pipes, cables, ducts, soil stacks — moving with them instead of cracking. Because it’s liquid-applied, it fits any shape or cluster, where pre-formed grommets can’t.
How it is applied
- Clean around the penetration and the surrounding membrane
- Paint the liquid grommet around the service to form a collar
- Tie it into the wall’s airtight or waterproof layer
Benefits
- Custom seal around any penetration
- Stays flexible — won’t crack
- Airtight and watertight
Frequently asked questions
Does it work on cable bundles? Yes — being liquid, it seals around irregular bundles and multiple services.
Indoor and outdoor? It forms an airtight and watertight seal; check the product page for exposure guidance.
See how penetrations fit the airtight layer in How to Make a Building Airtight.