Best Caulk For Sill Plate

Ordinary foam sill sealer works best as a capillary break but it doesn t always work so well as an air seal.

Best caulk for sill plate.

One option for improving the air seal if you use conventional sill seal is to seal from the inside with high quality polyurethane or a siliconized acrylic caulk formulated for adhering to concrete. In other words caulking is applied where moisture would otherwise penetrate and cause deterioration. Caulking is a sealant that fills gaps cracks nail holes and similar imperfections on the surface. Best uses for silicone sealants silicone is very flexible and acts as a water and moisture repellant making silicone sealants the best caulk for windows and bathrooms.

Flexible foam sealant designed for use on both wood and masonry is the best type of caulking for sealing the sill plate. If you have a solid concrete foundation also run a bead of caulk where the sill plate meets the concrete. Sill sealer is a pliable foam product that is available in varying widths up to 10 inches wide. In this article we will go over typically caulked areas on the exterior typical northwest style homes and also areas that should never be.

If you have a concrete block foundation also seal the openings on top with expanding foam. Look for a sealant labeled minimal expansion. Stuff a wad of fiberglass insulation into each opening to support the foam as it hardens see figure a in the horizontal callout. The best way to air seal the sill plate is to place a sill sealer also called a sill gasket on the concrete before laying down the sill plate.

A filler similar to caulk is generally used to seal these gaps between the sill plate and foundation when the home is constructed. Fasten the sill plate to the concrete slab following the recommendations of the local building code. Some codes require that the sill plate be bolted to the slab while others recommend a metal.