Doors

TL;DR: How to Weatherstrip a Door

To weatherstrip a door, first find where air is leaking, then remove the old, worn weatherstripping and clean the door jamb. Measure the top and both sides of the frame, cut new weatherstripping to length, and install it so the door presses lightly against it when closed. Finish by adding or replacing the door sweep at the bottom. Foam tape is the easiest DIY option, while kerf-in (compression) weatherstripping and door sweeps give the longest-lasting seal. Most doors take one to two hours and less than $50 in materials.

Why Weatherstripping Your Door Matters

Gaps around exterior doors are one of the biggest sources of drafts in a home. Over time, weatherstripping compresses, cracks, and peels away, letting cold air in and warm air out. In a New England winter, that means higher heating bills, chilly entryways, and a furnace that runs more than it should.

Weatherstripping a door is one of the cheapest and fastest energy upgrades you can make. It also keeps out moisture, dust, insects, and outside noise. If you’re working through a list of winter projects, our guide to energy saving home improvements has more ideas.

Need a new door or trim for your project? Browse our exterior and entry doors, or reach out to Builders Surplus with your questions. You can also give us a call at 866-739-1636.

Find the Leaks First

Before you buy anything, figure out where the air is getting in. A few simple tests:

• Feel for drafts: On a cold or windy day, run your hand slowly around the edges of the closed door.
• Look for light: At night, turn on the outside light and look for light peeking around the frame from inside (or have a helper shine a flashlight from outside).
• The paper test: Close the door on a sheet of paper. If it slides out easily, the seal at that spot is too loose.
• The candle or incense test: Hold a lit incense stick near the edges. If the smoke wavers, you’ve found a leak.

Also check the threshold and the bottom of the door. That’s where many of the biggest gaps hide.

Choose the Right Weatherstripping

How to pick: Pull back a corner of your existing weatherstripping. If it’s pressed into a thin slot in the door frame, buy kerf-in replacement in the same profile. If it’s stapled or stuck on, foam tape, V-strip, or a tubular gasket will work.

Gather Your Tools and Materials

• Weatherstripping for the top and sides of the door
• Door sweep (if the bottom gap needs it)
• Tape measure and pencil
• Utility knife or tin snips
• Hacksaw (for metal or rigid door sweeps)
• Screwdriver or drill
• Putty knife or flat pry bar
• Rubbing alcohol and a clean rag

How to Weatherstrip a Door Step by Step

Step 1: Remove the old weatherstripping. Pull out kerf-in strips by hand, or use a putty knife to scrape off old foam and adhesive. Pull any staples or small nails.

Step 2: Clean the surface. Wipe the jamb with rubbing alcohol and let it dry. Adhesive weatherstripping won’t stick to dirt, grease, or old residue. Install on a day above 50°F if you can, since adhesives bond poorly in the cold.

Step 3: Measure. Measure the head jamb (top) and both side jambs. Measure each side separately, since frames are rarely perfectly square.

Step 4: Cut and install the top piece. Cut the weatherstripping to length and install the top first. For kerf-in strips, press the flange into the slot with your fingers or a putty knife. For foam tape, peel the backing a few inches at a time and press firmly as you go.

Step 5: Install the sides. Run the side pieces from the top down, butting them tightly against the top piece so there’s no gap in the corners. Place the weatherstripping on the door stop so the door presses against it when closed.

Step 6: Test the door. Close and latch the door. It should close with light resistance and seal evenly. If it’s hard to latch, the weatherstripping may be too thick. If you still feel air, you may need a thicker profile.

Don’t Forget the Door Sweep

The bottom of the door is often the worst offender. A door sweep is a strip of rubber, vinyl, or brush bristles that attaches to the bottom of the door and seals against the threshold.

1. Measure the width of the door and cut the sweep to fit.
2. Close the door and hold the sweep against the inside bottom edge so the seal lightly touches the threshold.
3. Mark the screw holes, pre-drill, and screw it in place. Slotted holes let you adjust the height later.

If the threshold itself is worn, cracked, or rotted, replacing it (or upgrading to an adjustable threshold) may be the better fix. And if the door frame or trim is damaged, our guide on how to replace exterior door trim can help. When the door is warped or the frame is too far gone, weatherstripping can only do so much. A new prehung exterior door comes with factory-installed weatherstripping and a tight seal from day one.

Final Thoughts on Weatherstripping a Door

Learning how to weatherstrip a door is a quick, affordable project that pays off every month in lower heating bills and a more comfortable home. Find the leaks, choose the right type of weatherstripping, install it carefully, and finish with a good door sweep. Check your seals each fall before the cold sets in, and replace them as soon as they start to crack or flatten.

Find Quality Doors and Trim at Builders Surplus

Whether you need a new entry door, trim, or moulding to finish the job, Builders Surplus has a large selection at surplus prices. Visit one of our locations in Warwick, West Warwick, and Central Falls, RI; Jewett City, CT; and Lunenburg, MA. You can also reach out to Builders Surplus online or call us at 866-739-1636. Our team is happy to help you get your home ready for winter.

FAQ: How to Weatherstrip a Door

What is the best weatherstripping for an exterior door?

For most modern exterior doors, kerf-in compression weatherstripping is the best choice because it lasts for years and seals tightly. Pair it with a door sweep at the bottom. Foam tape works for quick fixes but wears out faster.

How often should door weatherstripping be replaced?

Inspect weatherstripping every fall and replace it when it’s cracked, flattened, torn, or peeling. Foam tape may need replacing every one to three years, while rubber and vinyl compression strips can last much longer.

Can I weatherstrip a door in the winter?

Yes. Kerf-in strips and screw-on door sweeps can be installed in any weather. Adhesive products bond best above 50°F, so warm the surface with a hair dryer if you need to install them on a cold day.

Why is my door hard to close after weatherstripping?

The weatherstripping is likely too thick for the gap. Try a thinner profile, or adjust the strike plate so the door latches without forcing it.

How do I seal the gap at the bottom of my door?

Install a door sweep on the inside bottom edge of the door so it lightly touches the threshold. If the gap is large or the threshold is damaged, replace the threshold or add one with an adjustable vinyl insert.