The number-one, do-it-yourself energy reduction device is cheap and easy to install, but definitely not glamorous. It’s caulking. Plugging those little cracks and crevices around doors, windows, and other wall penetrations to seal air leaks provides an immediate reduction in your energy bill--especially during the winter months. Experts estimate that your energy savings will pay back the cost in just one year. It’s also a project that you can start and stop easily, so it’s possible to work on it a few hours at a time on weekends.

   The pie chart above represents the U.S. Department of Energy’s analysis of what percentage of air leakage is attributed to which structural component in the home: it shows that small openings in doors, walls, and ceilings are a significant part of the energy loss in an average home. In the Gainesville, Florida area that we serve, “buy a case of caulk and a good caulk gun--one that costs more than $5” is always our first energy-savings recommendation for new homeowners.

   While not expensive, caulking is labor-intensive and requires some trial-and-error practice. A tube of premium latex caulk is our choice, and it’s cheap: less than $3 at the big-box home improvement stores. Plus, latex is likely the best choice for do-it-yourselfers, since mistakes wipe away with a little water and a wet cloth and, once hardened, the surface takes paint well.

   The primary thing to understand when beginning a caulking project is that it involves more than just squeezing out a line of goo. Here’s two basic techniques you can use to make a good caulk joint/seam:

1. The tip of the caulk gun should be positioned so that the caulk is pushed slightly into the opening it is filling as it is run along, rather than just sitting on the surface. Most pros cut the tip of the caulk gun at about a 45º to 60º angle, with a slightly smaller opening than the size of the bead of caulk you want to lay down, then hold the gun at a similar angle while running the bead line, and the angled cut at the tip forms a hood over the top of the bead as it comes out of the caulk gun, pushing it a little downward. 
2. Lightly wipe over the line of caulk after it is laid down, with an index finger that has been dipped in cool water. This creates a concave surface at inside corners and smooths the edge to blend into the adjacent surfaces. Water keeps the caulk from sticking to your finger. Be careful not to wipe away most the caulk. The objective it to smooth everything out gently. This is the part that takes some practice. And, of course, remember to rewet your finger after each stroke or two.

   The mark of a good caulk job is that it becomes invisible when painted over at completion, pulling everything together into one seamless piece--which is also a good way to judge your work when you’re done.

    Here’s a complete list of recommendations for caulking and other ways of sealing air leaks around your home from the U.S. Department of Energy:

1. Test your home for air tightness. On a windy day, carefully hold a lit incense stick or a smoke pen next to your windows, doors, electrical boxes, plumbing fixtures, electrical outlets, ceiling fixtures, attic hatches, and other places where air may leak. If the smoke stream travels horizontally, you have located an air leak that may need caulking, sealing, or weatherstripping.
2.  Caulk and weatherstrip doors and windows that leak air.
3.  Caulk and seal air leaks where plumbing, ducting, or electrical wiring comes through walls, floors, ceilings, and soffits over cabinets.
4.  Install foam gaskets behind outlet and switch plates on walls.
5.  Inspect dirty spots in your insulation for air leaks and mold. Seal leaks with low-expansion spray foam made for this purpose and install house flashing if needed.
6.  Look for dirty spots on your ceiling paint and carpet, which may indicate air leaks at interior wall/ceiling joints and wall/floor joists, and caulk them.
7.  Cover single-pane windows with storm windows or replace them with more efficient double-pane low- emissivity windows.
8.  Use foam sealant on larger gaps around windows, baseboards, and other places where air may leak out.
9.  Cover your kitchen exhaust fan to stop air leaks when not in use.
10.  Check your dryer vent to be sure it is not blocked. This will save energy and may prevent a fire.
11.  Replace door bottoms and thresholds with ones that have pliable sealing gaskets.
12.  Keep the fireplace flue damper tightly closed when not in use.
13.  Seal air leaks around fireplace chimneys, furnaces, and gas-fired water heater vents with fire-resistant materials such as sheet metal or sheetrock and furnace cement caulk.

    One last thing: remember that it is important to caulk around the inside of wall and door openings too. An opening like the one shown below leaks air through the wall cavity. 

    Also, see our blog post What causes air leakage energy loss in a house?

      Visit our ENERGY EFFICIENCY page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.