Chalk it up to Caulk


Designing and building your home to decrease moisture and mold intrusion is important, but even the best efforts can be wasted without proper maintenance. Maintaining your home’s weather-resistive properties is a simple but effective method of protecting your investment for years to come.

With a minimal amount of time and effort, you can protect your home from moisture intrusion. For example, walking around the house during a heavy rain will reveal how water flows from the roof to the gutters and away from your house. You’ll see how water flows around windows, doors and utility penetrations and be able to evaluate the effectiveness one of the most troublesome areas —  caulked joints.

Industry research has determined that bulk water intrusion from the exterior is responsible for the majority of moisture-related problems. Bulk water can account for gallons of water entering the wall cavity in a short period of time. Where does the bulk water come from? Through poorly sealed windows, siding and doors. Not only is this a source of moisture, it accounts for a significant amount of heat loss as well. According to researchers at Michigan State University, the money you spend on caulking or weatherstripping is usually recovered in one heatingseason or less.

Tools needed include caulk, caulk gun, blunt scraper, utility knife, rubber gloves, wet rags, rubbing alcohol and soapy water.

Exterior Caulking Inspection

Annually inspect the following areas during the dry season:

Corners, angles and butt joints where siding materials meet;
The interface between siding materials and trim;
The joint where the foundation and siding meet;
Window, skylights and door frames;
Hose bibs, pipes, wiring outlets and vents in exterior walls.


Replacing Window Caulk

Have you walked down the caulking and sealants aisle of your local big-box hardware store lately? Deciding on the type of caulk to use may be the most difficult part of the job. Caulks come in a variety of price points, colors and chemical compositions. If you are repainting the house, then choose an opaque, paintable caulk. If you’re between paint jobs, consider using a clear, paintable caulk.

Most manufacturers recommend removing all old caulk using a chemical caulk remover, putty knife or other blunt-end, thin tool. Stubborn caulk may be carefully cut out with a utility knife, but proceed slowly to prevent gouging the window or wood trim.

Caulking compounds are best applied when outdoor temperatures are between 50 and 70 degrees. This is when most building materials are at the midpoint of contraction and expansion. First clean the surface of the window frame with rubbing alcohol or other cleaning compound to ensure good adhesion.

Place a foam backer rod in seams more than 1/2-inch wide or 1/4-inch deep.

Using a caulk gun held at 45 degrees, push the bead ahead of the nozzle. Do not fill the weep holes at the base of the window. These are an important moisture-release element to the window design. Use a spoon dipped in soapy water to apply a smooth finish before the caulk cures.

This home was built in 2001 and already shows signs of cracked caulk and gaping wood. Use a blunt scraper to remove the old caulk.


Door with caulk removed.


Cracks in siding seams also offer a path for moisture to enter your home. Often, caulk will become brittle and crack under normal weather conditions. It is important to inspect your siding yearly to determine if any cracks exist or if any joints were overlooked at the last painting. As with windows, the best time to inspect and replace caulking is during the dry season. If you are between paint jobs, clear paintable caulks are available that will blend with the house color.

To replace caulk on a siding seam, first remove all old caulk using a chisel, screwdriver, scraper or other tool. For a seam gap wider than 1/2 inch or deeper than 1/4 inch, use a foam backer rod cut to the size of your siding. Push the backer rod into the seam using a screwdriver or similar tool, making sure there is at least 1/4 inch of clearance for the caulk to fill the inside of the joint.

Using a caulk gun held at 45 degrees, push the bead ahead of the nozzle. Be sure you completely fill the seam with caulk. Again, use a spoon dipped in soapy water to apply a smooth finish before the caulk cures.



Checking the weatherstripping along doors is an important first step in ensuring proper maintenance. Similar to windows and siding, proper sealing of doors necessitates annual inspection of the caulk. Detrimental weather conditions can cause caulking to disintegrate, leaving gaps for air and moisture to enter. Follow the procedures outlined earlier.

While you have the caulk gun out, look around your home for other places that could use recaulking, keeping in mind that not all areas will receive the same type of caulk. There are specialty sealants for the joints of gutters and downspouts; kitchens and bathroom backsplashes; and plumbing fixtures. Plumbing vents in particular can be problematic because they run from below the floor all the way through the roof. Every duct, wire or pipe that penetrates the building envelope has the potential to waste energy.

Pushing rather than pulling the bead helps the caulk penetrate the gap.
The caulk used on this job was clear silicone, which works well on vinyl-to-wood and wood-to-wood surfaces.

With these simple steps, you can save on energy costs, prevent significant damage to your home from moisture and protect your investment. Caulking is just one aspect of an annual maintenance regiment to protect your home from moisture intrusion, however. APA — The Engineered Wood Association is launching a new educational program to help homeowners identify and correct potential sources of moisture intrusion. The program, Maintain A Better Home, offers recommendations for homeowners’ exterior and interior inspections and repairs. Look for other steps you can take to ensure your home lasts you a lifetime at

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