The greatest sources of heating and cooling losses in your home are often invisible?air leaks. As a result, controlling air leaks provides the best way to extend the life of your home, conserve energy, save money, and increase comfort.

Bottom line? If you don’t tighten up your home first, money spent on insulation may be wasted.

Fortunately, you can seal a lot of leaks around your home’s exterior with less than $100 worth of caulk. It’s generally possible to seal openings up to one-quarter inch between window frames and siding or around door frames. For larger gaps, add a backing material before caulking, or use a spray foam sealant instead.

Most types of outdoor caulk are sold in tubes that fit a caulking gun. In addition, some caulks come in aerosol cans; they’re a good choice for filling gaps up to one-half inch around pipes and wires.

When shopping for caulk, there are myriad choices. Prices range from a couple of dollars to several dollars per tube, so be sure to read the labels and choose a product that will adhere best to the materials you’re sealing.

If your budget allows, spend a little more for a higher-quality caulk. Inexpensive caulks may last only a few years, while premium-priced caulks are rated for 20 years or more.

Caulk like a Pro

  • As a rule of thumb, you’ll probably use half a cartridge per window or door and up to six cartridges for foundation work.
  • Most caulks pose no known health hazards after they’re fully cured. However, some high-performance caulking compounds contain irritating or potentially toxic ingredients, so you should carefully read the manufacturer’s instructions and take the appropriate precautions.
  • The best time to apply caulk is during dry weather when outdoor temperatures are above 45 degrees. Low humidity is important during application to prevent cracks from swelling with moisture.
  • If the gap you’re sealing is too wide, use a special filler made for the purpose. You’ll find fillers in the caulking department of your local hardware store or home center. However, note that fillers are not designed for exposure to the elements; so you’ll need to caulk or seal over it.
  • Before applying new caulk, remove the old caulk or paint residue with a putty knife, stiff brush, or special solvent.
  • Make sure your work area is dry, so you won’t seal in moisture.
  • Hold the caulking gun at a consistent angle; 45 degrees is best.
  • Caulk in a straight, continuous stream, avoiding stops and starts, and make sure the caulk sticks to both sides of the crack or seam.
  • Send caulk to the bottom of an opening to avoid bubbles.
  • Release the trigger on the caulking gun before pulling it away from the crack to prevent applying too much caulk. A caulking gun with an automatic release makes this much easier.
  • Don’t skimp. If the caulk shrinks, reapply it to form a smooth bead that completely seals the crack.
  • If caulk oozes out of a crack, use a putty knife to push it back in.
  • Once you’ve applied caulk, it takes time for it to dry, or cure. Curing time is described in two ways. The tack-free time tells you how quickly the fresh caulk’s outer surface will dry or skin over. The total cure time indicates the time required for the caulk to become completely stable—or reach the point where no further drying or shrinking will occur.
  • Don’t allow pets and small children to come into contact with fresh caulk.

Expanding foam for big gaps

  • Be sure to use the correct type of spray foam for the job. Polyurethane expandable spray foam works well around pipes and gaps around the foundation. However, this type of caulk expands with so much force that it can cause damage to window frames and door frames. In those spots, use a water-based spray foam specifically designed for the job.
  • Expanding foam is ideal for filling cracks that caulks can’t handle. It comes in aerosol cans and takes a short time to cure. The foam is very sticky and attaches itself quickly, so be prepared to pick up any messes fast.
  • To seal gaps too wide for foam, use foil-faced bubble wrap. For really large holes, cut sections of rigid foam insulation to fit and then glue into place with expanding foam before covering the area with wood or another appropriate building material.

Find more ways to seal your home and save at

Sources: U.S.  Office of Energy Efficiency and Renewable Energy, ENERGY STAR, and product manufacturers

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