Caulking and weatherstripping in an afternoon

Air leaks are among the biggest sources of wasted energy in a home, and sealing them can save 10 to 20 percent on heating and cooling bills. The leaks around windows and doors are the easiest to find, because you can feel them. Caulk seals the gaps that don't move, and weatherstripping seals the ones that do.

What you need

• Caulk and a caulking gun, rated for indoor or outdoor use as the job needs
• Weatherstripping sized for your doors and windows, sold by the foot or in kits
• A door sweep, if light shows under an exterior door
• An incense stick, a putty knife and a rag

Before you start

Steps

1. 1

   Find the leaks on a windy day

   Close the windows, exterior doors and fireplace damper, and turn off any fuel-burning appliance. Hold a damp hand or a lit incense stick near each window and door seam. A cool spot on your hand, or smoke blowing sideways, marks a leak.

   30 min

2. 2

   Try the paper test on each window

   Close the window on a sheet of paper. If the paper slides back and forth easily, the window needs thicker weatherstripping.

   15 min

3. 3

   Pick the right caulk for each spot

   Indoor and outdoor surfaces need different caulks. Some are waterproof and some aren't, and some can be painted. Read the tube, and follow its directions.

   10 min

4. 4

   Caulk the fixed gaps

   Run a bead of caulk along the gap where the window or door frame meets the wall. Outside, use a clear or paintable caulk around the whole frame. Caulk fills gaps up to 3/8 inch, and foam sealant fills gaps up to 1 inch. Around a window frame, use a foam with little or no expansion.

   60 min

5. 5

   Weatherstrip the door frame

   On the knob side and the top, fix the weatherstripping to the narrow leading edge of the door frame. On the hinge side, fix it to the wide trim the hinges attach to.

   45 min

6. 6

   Close the gap at the bottom of the door

   A door sweep on the bottom of the door, or a properly fitted threshold, cuts the air that slips underneath.

   30 min

7. 7

   Weatherstrip the windows

   Weatherstripping seals the gaps between the parts that move, such as a sash and its frame, when the window is closed. Try to match the type that came with the window.

   40 min

8. 8

   Check the seal with the door closed

   Well-installed weatherstripping is slightly compressed when the door or window is closed. Repeat the incense test at each seam you sealed. Smoke that rises straight up means the leak is closed.

   10 min

If something goes wrong