Some builders also use the same sill sealants around window frames.
A sill sealant is a type of insulation used at the base of exterior walls. During the home construction process, builders first build the floors out of wood or concrete. As they build the walls, they use a piece of wood or steel as a base to support each wall. This base, or sill, is attached to the floor frame with screws or studs to secure the wall in place. When a sill sealant is used, it is installed between the floor and the sill plate around the perimeter of the framing.
Often the material used to construct the floor of a new building is not perfectly level. This can be attributed to the material itself or poor construction techniques. Using a sill sealant compensates for these imperfections and helps ensure walls are level. Not only does this result in a better looking building, it also makes the construction process easier and reduces the risk of costly mistakes.
Like all types of insulation, sill sealants also block air infiltration between the sill and the floor. This improves the overall energy efficiency of the home, which often translates to lower heating and cooling costs. A more efficient home also tends to be more comfortable, as there are fewer cold drafts and less need to continually adjust the thermostat. By filling in the space at the base of each wall, sill sealant also helps prevent insect infestation and can also reduce the amount of unwanted moisture that enters the home.
Threshold sealants are usually made of foam or fiberglass. Sill sealant is usually less than an inch thick and should be cut the same width as the walls. Many have a built-in adhesive that makes it easy for installers to apply the sill sealant to the floor, although some may require glue or other fasteners. Many are treated with chemicals or borate to increase fire resistance and prevent mold growth if the sealant gets wet.
Some builders also use the same sill seals around door and window frames. The caulking can be placed between the floor frame and a door sill, or around the entire perimeter of a window frame. When used in this way, these products help improve energy efficiency and minimize air infiltration inside and outside the home. They also level the door or window in openings that are slightly uneven or uneven.