Outdoor Caulk

Fall is one of the best times to caulk outdoor areas of the home where cold air can seep in. Open joints create drafts and increase heating costs. Don’t heat the outdoors. Take the time to caulk exterior joints of your home. The price of caulk and the effort it takes to apply it can and will save a great deal of money in the long run.

Caulking Advice and Precautions

Keep in mind that caulk is meant for small cracks and gaps, and larger openings would be better sealed with expanding foam. If a gap or crack is more than 3/8 of an inch wide or deep, use expanding foam. It’s a great product that effectively seals larger openings.

Also, a tube of caulk that contains 10.5 ounces of product will generally seal a 40 to 50-foot line. Take this into consideration when purchasing caulk for outdoor jobs around the home. That’s roughly enough caulk to seal approximately four average size windows or three doors. You’ll use more or less depending on the size of the bead.

People are often tempted to smooth a bead of caulk with a bare finger. Caulk can be difficult to remove from the skin, and it contains potentially harmful chemicals. Don’t spread caulk with your finger. Use a simple tool such as a wooden craft stick or a small caulking blade. Your skin will stay clean and the caulk will be smooth and neater in appearance.

Butyl Rubber

Butyl rubber is best used to seal outdoor brick, concrete blocks, aluminum siding, chimneys, and metal flashing. When properly applied it can last up to 20 years. Butyl rubber caulk is flexible, it can be painted, and it can be used in damp locations above or below ground.

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On the downside, butyl rubber is slow to cure, it’s known to excessively shrink, it’s stringy, can be difficult to work with, and solvent is required for clean up.


If you have outdoor concrete blocks, bricks, metal, fiberglass, plastic, or wood siding that requires sealing, polyurethane is a good choice for home application. When applied properly, it can last between 20 and 50 years. Polyurethane caulk is an excellent product; its flexible, weather resistant, it can be painted, and it’s exceptionally strong.

Shortcomings are the higher than average cost, it’s flammable, toxic, and polyurethane caulk requires solvent for proper clean up, but all things considered, polyurethane is a great choice for outdoor use.

Acrylic Latex

Regular latex caulk isn’t suitable for outdoor use, but acrylic latex caulk is sufficient for sealing around windows, doors, and along seams of wood siding. It’s very easy to apply, and soap and water clean up is a breeze. Acrylic latex can also be painted if desired.

Negative aspects are a shorter life span, it isn’t suitable for damp locations, and it generally won’t bond well to nonporous surfaces or metal. If you want caulking that can last between 5 and 25 years that is reasonable in price, acrylic latex caulk is a great option for outdoor use.

Polymer Caulk

Polymer caulk is one of the strongest sealers you can choose for joining and sealing outdoor surfaces such as wood, metal, glass, tile, vinyl, stone, brick, concrete, and even asphalt. It can last between 30 and 50 years if properly applied, and it has all of the benefits of the aforementioned sealers plus more. Polymer caulk is tear resistant, and it can connect outdoor materials that won’t normally bond.

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On the downside, it shouldn’t be used near heat or flame because it is considered flammable. Also, polymer caulk can damage plastic products.


Silicone is a popular caulking material because it effectively seals metal, glass, and tile, and it can be applied to hard as well as smooth outdoor surfaces. Silicone caulk is highly flexible; it’s strong, it’s suitable for application in high as well as low temperatures, and it’s exceptionally weather resistant.

Disadvantages of silicone caulk are as follows. It can’t be painted to match other colors, the fumes are strong, it’s not suitable for brick, stone, or concrete, and it doesn’t work well with redwood or cedar siding. If you don’t plan on painting over sealed outdoor areas, all things considered, silicone caulk is still a good choice for suggested outdoor surfaces.

Caulking Tips

If you can’t reach an area that requires sealing, make a handy extender for your caulking tube. Rigid plastic tubing or a simple drinking straw makes a great extender. Simply tape it to the nozzle, and reach areas that would otherwise be inaccessible.

Periodically wipe off the end of the nozzle so the bead remains uniform in size and shape. A messy nozzle creates a messy bead, and a messy bead results in a sloppy overall appearance. The bead should range between 1/16 and 3/8 of an inch wide. Practice in an inconspicuous area before caulking noticeable outdoor locations.

For the best overall appearance, don’t release the handle of the caulking gun until you reach a seam wherever possible. The job will look neater and more professional when complete.

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Storing Caulk

Caulk isn’t exactly cheap, so there’s no reason to throw away an open tube. Keep open tubes of caulk from drying out by sealing the tips of the containers with appropriate size nails or screws. The tip will remain open but sufficiently sealed until you need to caulk other outdoor areas of your home.


  • DIYNetwork.com offers valuable tips and information on preparing your home for fall and winter.