Weatherstripping and caulk form the front line of defense against air leaks in your home. Air leakage into and out of the house is a major factor in poor energy efficiency, inconsistent comfort and even bad indoor air quality. New homes built today are constructed to a high standard of building tightness so air exchange with the outdoors is dramatically reduced.
If your home was built 10 years ago or more, however, you’re living in a house that probably admits hot air during summer through many inconspicuous cracks and gaps and lets heat out in winter the same way. Weatherstripping and caulk can help upgrade leaky existing houses to today’s standards of air tightness and efficiency. It also makes other improvements like upgrading insulation more effective.
Sealing air leaks isn’t a cutting-edge home improvement that will make your neighbors envious. Weatherstripping and caulk are more humdrum than high-tech. However, closing up the structural gaps and cracks in your house is probably the single most cost-effective measure you can take right now that will deliver the most benefit for the relatively few dollars you spend on it. Most houses will pay back your efforts with up to a 20 percent decline in energy costs.
Caulk is a flexible sealing compound used to fill cracks in the structure of your home. It applies as a paste-like consistency, usually out of a disposable cartridge loaded into a caulking gun, and dries to a flexible, airtight and waterproof seal. Caulk also comes in aerosol cans, usually spray polyurethane, as well as ropes that may be stuffed in irregularly shaped openings. Caulk is used to close gaps between two surfaces that don’t move. The most common household caulking, a silicone compound, is appropriate to fill and seal openings 1/4-inch or less wide.
Weatherstripping is installed to seal the gaps between movable surfaces. Common examples include the contact point between an exterior door and the door frame or the gap between double-hung windows. Weatherstripping typically degrades or simply wears away over time so the gap between surfaces is no longer sealed and air can leak in or out.
The simplest form of weatherstripping is adhesive-backed foam tape that’s self-sticking and easily applied anywhere it’s needed. More expensive but more effective are strips of bulb-style weatherstripping made of vinyl or rubber. Although self-stick bulb-style varieties are available, the most permanent installation are the nail-on types.
Apply caulking to seal straight cracks and gaps such as between the baseboard and floor and along the intersection between walls and between the ceiling and walls. Make sure the surface is clean and free of old caulking first. Hold the caulking gun at approximately a 45-degree angle to force caulking directly into the crack. Squeeze the trigger and apply caulking in a continuous bead, keeping the gun moving until the end of the area to be sealed. Release the trigger as you near the end of the crack. Use a putty knife to smooth the application and ensure that all caulking penetrates into the crack instead of oozing out. Silicone caulking generally requires 24 hours to cure completely.
For cracks wider than a quarter-inch or for large irregular shaped gaps, such as the opening around plumbing pipes or electrical conduits where they penetrate the structure, use polyurethane spray foam. Available in 12-ounce or 16-ounce cans and injected into openings, spray foam will rapidly expand to fill the gap. Spray foam is generally dry within an hour.
To determine the amount of weatherstripping you’ll need, measure the perimeter of all doors and windows and add together for a total length in inches. First, remove any remaining worn or deteriorated weatherstripping that may still be in place. Install weatherstripping to the surface of the door or window to be sealed where it contacts the opposite surface. The weatherstripping should compress slightly when the door or window is closed. However, it should not be so thick that it binds during opening or closing. This will quickly wear down the material and degrade the seal.
Don’t forget the large opening between the bottom of the door and the threshold. An aluminum or stainless steel door sweep with a sealing brush made of plastic, vinyl or rubber will prevent the large flow of leaking air through the gap.
For more on the household science of sealing with caulk and weatherstripping, ask the professionals at Valderrama A/C & Refrigeration.
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