Window Caulking near you

Each side of a window has a different job. Inside, caulking is air sealing: Natural Resources Canada's window guide recommends a continuous bead where the casing meets the wall, at the mitred corners of the casing and between the casing and the frame, using a good-quality caulk made for indoor use that can be painted. It specifically warns against using exterior caulking indoors. Outside, the bead between the frame or its trim and the cladding is mainly there to keep rain out of the wall.

Order matters as much as the product. NRCan advises caulking the outside of a window only once interior sealing is complete, because a window sealed on the outside first can trap warm, moist indoor air in the wall, which can damage it over time. A careful contractor seals the inside, checks the outside joints, and only then closes them. A draft between the sash and the frame is a different problem, handled by weatherstripping on the window repair side.

NRCan's advice for windows is to check for air leakage around the frame and at every movable joint, pairing a visual inspection with a simple leak test, before any old caulk comes out.

Windows are built to drain away water that gets past their outer seals, so a good installer closes some joints and deliberately leaves others open.

NRCan's materials guide compares common caulks by durability, joint movement and the surfaces they bond to, and the types differ widely, so the label and the window maker's instructions settle the choice.

Most of a window caulking job is removal and cleaning. A new bead only lasts if it bonds to clean, sound and dry surfaces on both sides of the joint, and very little will stick to old silicone or to caulk that is already failing.

Interior window caulking can be done in any season, and the heating season, when drafts are easy to feel, is a good time to find and seal them. Outside work is another matter: each sealant lists an application temperature range and a requirement for dry, frost-free surfaces, and those limits vary by product, so exterior window joints are best planned for mild, dry days, following the label rather than a rule of thumb.

When a window leaks badly in midwinter and the outside can't be sealed yet, NRCan describes inexpensive, temporary heat-shrink plastic film kits: double-sided tape holds the film on the window trim and a hair dryer shrinks it tight across the opening. It cuts the draft until spring, but it doesn't replace sealing the joints.

Casings and sills in older homes often carry many coats of paint, and cutting out old caulk means scraping right against them. Health Canada says a home built before 1960 probably contains lead-based paint and that the exterior of one built between 1960 and 1990 may. Paint chips can be sent to a lab for analysis, or a contractor with x-ray equipment can check the painted surfaces on site.

Health Canada warns against sanders, heat guns and blowlamps on lead-based paint, since they create toxic dust and fumes, and advises keeping children and pregnant women away from the work area. Scrapings and chips go in a sealed container marked as hazardous waste and are disposed of as the municipality directs. Health Canada also lists caulking among the materials in older buildings that may contain asbestos, so hard original caulking should be tested before it is cut out.