caulking

Caulking is a pliable sealant material used to fill gaps and joints in building assemblies, with the purpose of preventing air and water intrusion, reducing drafts, and accommodating substrate movement. It is applied around windows and door frames, sinks and bathtubs, countertops, baseboards, and exterior joints, as well as expansion joints in concrete and masonry.

Common caulking materials include silicone-based, polyurethane, acrylic latex, and polysulfide formulations. Silicone sealants are highly flexible and water resistant, making them popular for bathrooms and exterior use, though some are not paintable. Polyurethane sealants offer strong adhesion and durability on a wide range of substrates but require thorough surface preparation. Acrylic latex caulk is easy to apply and paintable, suitable for interior use, and cleans up with water. Hybrid formulations combine properties of different types. Some silicones are acetoxy-curing (releasing acetic acid) and can odor and corrode metal; neutral-curing silicones cure without strong fumes and are often preferred for sensitive substrates.

Preparation and application involve cleaning and drying all surfaces, removing old caulk, and, for wide gaps, inserting backer rod to control depth. A compatible primer may be needed on porous or non-porous surfaces. Cut the cartridge nozzle to the desired bead size, load in a caulking gun, and apply a continuous bead. Tool the bead with a damp finger or a caulking tool to ensure adhesion and a smooth finish, then remove masking tape promptly. Allow the sealant to cure undisturbed for the specified time.

Maintenance includes inspecting seals for cracking or mold, and replacing caulk that no longer adheres or remains flexible. Proper disposal and ventilation are advised during application.