Caulking

What It Means

Caulking is filling cracks and gaps between fixed parts of a house with caulk, a flexible sealant that comes in a tube. In energy terms it's one of the two basic ways to stop air leaks: the U.S. Department of Energy (DOE) uses caulk for joints between parts that stay still, such as a window or door frame against the wall, and weatherstrippingWeatherstrippingStrips of material fitted around doors and windows that open and close, sealing the gaps where air leaks in and out. See more for parts that open and close. Timing matters, because caulk needs dry, mild weather to set and grip.

How It Sounds at Home

• "There's a gap where the window frame meets the siding."
• "I'll run a bead of caulk along there this weekend."
• "The old caulk is cracked and pulling away."

The Breakdown

How to do it, following DOE's guidance

1. Find the gaps between fixed parts. DOE lists door and window frames and the places where plumbing, ducts or electrical wiring pass through walls, floors and ceilings, including soffits above kitchen cabinets.
2. Check each one is a fixed joint. Anything that opens and closes gets weatherstripping instead.
3. Choose a dry day with low humidity when it's above 45°F outside. DOE explains that dry air keeps cracks from being swollen with moisture, and warmth lets the caulk set and bond.
4. Pick a caulk made for the spot and read its label for how to prepare the joint, how to apply it and how long it needs to cure.
5. Once it has cured, look the joint over and touch up any spot the bead missed (Buhata's suggestion).

Try it today. Walk the outside of the house and the rooms where pipes come through walls, such as under the kitchen and bathroom sinks. Note every gap you can see light or feel air through. That list is your caulking job for the next dry, mild day.

Why bother. DOE calls sealing air leaks a cost-effective way to cut heating and cooling costs and improve comfort, and says caulking and weatherstripping often pay back within a year or less.

Good to Know

Never caulk over moldMoldA fungus that grows indoors wherever moisture lingers. EPA says fix the water problem, then scrub it off hard surfaces with detergent and water. See more; clean and dry the area first, as Buhata's mold page explains. DOE's payback figure of a year or less is typical, not guaranteed. Follow the caulk's label on ventilation, cleanup and cure time. Buhata's seasonal home maintenanceSeasonal home maintenanceHome upkeep sorted by time of year, so each job lands when the weather suits it and before the system it protects is needed most. See more page puts outdoor caulking in the fall, on a dry day above 45°F.

Related Terms and Categories

• Weatherstripping

  Strips of material fitted around doors and windows that open and close, sealing the gaps where air leaks in and out.

• Grout vs caulk

  Grout fills the joints between tiles on one flat surface; caulk, a flexible sealant, goes where surfaces meet at an angle or can move, like a tub edge.

• Insulation R-value

  A number that rates how well insulation resists heat flowing through it. The higher the R-value, the better it insulates.

• Seasonal home maintenance

  Home upkeep sorted by time of year, so each job lands when the weather suits it and before the system it protects is needed most.

• Mold

  A fungus that grows indoors wherever moisture lingers. EPA says fix the water problem, then scrub it off hard surfaces with detergent and water.

• Grout sealing

  Brushing or rolling a sealer onto grout lines so they soak up less water and fewer stains. Makers suggest resealing about every year or two.

Home maintenance and repairs