Is sill seal required by building code?

Yes. Most building codes including the IRC require a sill seal or gasket between the foundation and wood sill plate.

What thickness of sill seal should I use?

Standard 1/4-inch foam sill seal is sufficient for most applications. Use 1/2-inch in climates with significant temperature swings.

Sill Seal Calculator

Calculate rolls of sill seal gasket needed for your foundation perimeter to prevent air infiltration.

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Enter Your Measurements

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How to Use This Calculator

1Measure your total foundation perimeter in linear feet.
2Enter the roll coverage (most rolls are 50 ft).
3Click Calculate to see how many rolls you need.

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About This Material

Sill seal is a foam gasket material that goes between the concrete foundation and the pressure-treated sill plate. It prevents air infiltration, moisture wicking, and insect entry.

Installation Tips

•Unroll sill seal along the foundation just before placing sill plates.
•Overlap seams by at least 6 inches.
•Use PT-compatible sill seal — some foam degrades with treated lumber chemicals.

Common Mistakes to Avoid

Forgetting to install sill seal — it is a code requirement in most jurisdictions.
Not overlapping seams, leaving gaps for air infiltration.