As temperatures drop, you might notice cold air sneaking in around doors and windows. Drafts make rooms feel chilly, push your heating system to work harder and can let in dust and insects too. The good news is that sealing most drafts is an easy, inexpensive weekend project that doesn’t require special skills.

This guide walks you through finding leaks, choosing the right materials and installing weatherstripping, door sweeps and caulk.

Step 1: Find the drafts

Before buying anything, figure out where air is getting in. Try these simple tests on a cool, windy day:

  • The hand test: Run your hand slowly around door and window frames. You’ll often feel cool air.
  • The paper test: Close a door or window on a sheet of paper. If it slides out easily, the seal is weak.
  • The light test: At night, have someone shine a flashlight around the edges of a closed door from outside. Light coming through means air is too.
  • The incense test: Hold a lit incense stick near frames and watch for the smoke wavering or blowing sideways. Keep it away from curtains and never leave it unattended.

Make a list of each problem spot and note where the gap is: the sides, the top or the bottom.

Step 2: Choose your materials

Different gaps call for different fixes. Here are the most common options:

  • Adhesive foam tape: Cheap and easy to apply. Great for window sashes and door frames that don’t get heavy use, though it wears out sooner.
  • V-strip (tension seal): A folded strip of plastic or metal that springs open to seal gaps along the sides of doors and sliding windows. Durable and nearly invisible.
  • Rubber or silicone tubular gaskets: Good for irregular gaps and high-traffic doors.
  • Door sweeps: A strip of rubber, vinyl or brush attached to the bottom of a door to seal the gap above the threshold.
  • Caulk: For sealing gaps where window and door frames meet the wall. Use exterior-grade caulk outside and paintable acrylic latex inside.

Bring your measurements to the hardware store and buy a little more than you need.

Step 3: Gather your tools

You’ll likely need:

  • Measuring tape
  • Scissors or a utility knife
  • Screwdriver or drill (for door sweeps)
  • Caulk gun
  • Rubbing alcohol and a clean cloth
  • A putty knife or scraper for removing old caulk

Step 4: Install weatherstripping

Follow these steps for most adhesive types:

  1. Clean the surface. Scrape off old weatherstripping and wipe the area with rubbing alcohol. Adhesive won’t stick to dust or grease.
  2. Measure twice, cut once. Cut each piece to length for the side or top of the frame.
  3. Apply in a warm, dry spot. Most adhesives work best above about 50°F (10°C), so do the job on a mild day.
  4. Press firmly. Peel the backing a little at a time and press along the full length.
  5. Test the door or window. It should close snugly without forcing. If it sticks, try a thinner material.

Step 5: Add a door sweep

For a gap under an exterior door:

  1. Measure the width of the door and cut the sweep to fit.
  2. Close the door and position the sweep so its bottom edge just touches the threshold.
  3. Mark the screw holes, drill pilot holes and screw it in place.
  4. Open and close the door a few times to make sure it doesn’t drag.

Step 6: Caulk the gaps

Caulk works on stationary gaps, such as where a window frame meets the siding or interior trim. Remove old, cracked caulk first, clean the area and apply a steady bead. Smooth it with a damp finger or a caulk tool, then let it cure according to the label before painting.

Never caulk the moving parts of a window or door. That’s what weatherstripping is for.

Quick extras for older homes

  • Window insulation film kits add an extra layer to drafty single-pane windows for the winter.
  • Draft stoppers (fabric “snakes”) placed at the bottom of interior doors are an easy, renter-friendly option.
  • Outlet gaskets behind switch plates on exterior walls can block surprising drafts.

Safety notes

Don’t seal vents, flues or air intakes for heating appliances, which need airflow to work safely. If you use gas or wood heating, make sure you have working carbon monoxide detectors, especially after making your home more airtight.

The bottom line

A few hours and some basic supplies can make your home noticeably cozier this winter. Find the drafts, match the right material to each gap and seal them carefully. You’ll feel the difference the next cold, windy night.

Image: Baby blue door and yellow walls (Unsplash) by André Branco andre_branco via Wikimedia Commons, CC0 1.0