caulks and air sealing

Caulks are applied to air seal small gaps (less than 1/2" wide). Different locations may demand different caulks, responding to different temperatures, frictions, pressures, movements or weather exposure...

Caulk quality

Caulks have different prices and qualities. Look for a caulk capable of remaining flexible for many years. Avoid the cheapest caulks. Caulks based in silicone and polyurethane are excellent in most situations.

Selecting Caulks

Pay attention to price, and to the caulk’s label. Caulks vary in strength and properties. On doubt choose a high-quality caulk (based on polyurethane or silicone). The label should tell you whether the caulk is suitable for what you want to seal.

If the caulk is to be applied for penetrations bordered by different materials (wood, cement, glass, aluminum, steel…) pay special attention to the choice of the caulk. The adherence of the caulk to the different materials is crucial.

If the caulked joint is going to be visible, take into account the caulk's color or choose a caulk you can paint (silicone can’t).

Pay attention to the caulk grade: interior, exterior, high temperatures…

When not to apply caulks

Do not apply caulks in large penetrations and cracks (more than 1/2” wide). In these cases, foams are usually preferable. Caulks can be applied where two surfaces meet (such as at window and door trims) but not to surfaces subject to movement (in the movable parts of windows and doors you use weatherstripping materials, not caulks).

When sealing joints involving materials highly responsive to temperature (metal, plastic, glass…) it’s often preferable to use gaskets instead of caulks. Only highly flexible caulks can respond adequately to variations in the temperature.

Moisture

Some caulks will also prevent moisture and water damage, inside or outside the home. There are caulks (silicone…) largely applied around faucets, water pipes, drains, ceiling and plumbing fixtures...

Cartridges, caulking guns and quantities

For small jobs or special applications you may buy an aerosol can or a squeeze tube…

For larger works, there are disposable cartridges, fitting in half-barrel caulking guns (some pressurized cartridges do not require caulking guns). You will probably need about a ½ cartridge per window/door or 4 cartridges for the foundation sill (that’s just indications to help you estimate your needs)...  

See also: How to apply calks

See also: