Drafts and air leaks — finding them and sealing them up

This article is for educational purposes only and is not a substitute for professional advice. Local codes, regulations, and best practices vary by region.

Your house feels drafty. You can feel cold air coming in around windows in winter or warm air leaking around doors. Your heating or cooling system seems to work overtime but never quite catches up. The problem is air leaks—gaps and cracks where conditioned air escapes or outside air sneaks in. Finding the leaks is harder than fixing them, but both are manageable with a methodical approach.

Air leaks happen everywhere. Every place two materials meet creates a potential leak point. Around door and window frames, where pipes and wires enter the house, at foundation seams, in attics where walls meet the roof—these are all places where air finds its way in or out. The leaks you can feel (a breeze across your hand) are the obvious ones. Many more are invisible but still costing you money.

Start by feeling for drafts with your hand or a lit incense stick. Move slowly around doors, windows, and baseboards. You’ll feel cold air in winter or warm air in summer where leaks exist. Windows and doors are the most obvious places. Put your hand around the frame on a windy day and you’ll quickly identify problem areas. But don’t stop there. Check around electrical outlets, especially on exterior walls. That’s less obvious but outlets on outside walls are notorious leak points because the outlet box penetrates the outer wall insulation.

Look for gaps where utilities enter your house—pipes for water, wires for electricity, HVAC ducts. Anywhere something goes through the wall is a leak opportunity. In basements or crawlspaces, check where the foundation meets the house framing. In attics, look where walls meet the sloped roof. These seem like minor gaps but they add up. An audit by a professional with thermal imaging can identify leaks you’d never find by hand, but starting with manual detection is free and works for most common problems.

Sealing doors starts at the bottom. Door sweeps are thin strips that attach to the bottom of the door to block air. They cost $10 to $30 and are easy to install. The sweep should brush against the floor but not so hard it resists opening or closing. Weatherstripping around the other three sides of the door frame seals the gap between frame and wall. Weatherstripping comes in multiple types—foam tape, rubber, or felt. Foam tape is easiest for DIY installation. It peels and sticks. The whole job costs $20 to $50 and takes minutes. Caulk around the outside of the door frame seals the larger gap between frame and wall structure. This is more permanent than weatherstripping but also more work.

Windows get the same treatment. Caulk around the outside frame seals gaps between window and wall. Weatherstripping on the inside around the sashes seals the movable parts. This is basic caulk work—anyone with a caulk gun can do it. In winter, temporary window film (plastic sheeting taped over the window frame) creates an insulating air gap that significantly reduces drafts. It’s temporary but effective if you’re in heating season.

Electrical outlets on exterior walls are easy to fix. Buy foam gaskets designed for outlets—they cost about $1 or $2 each. Turn off the breaker, remove the outlet cover plate, stuff the foam gasket behind the outlet box to block air, and reinstall the cover. Takes two minutes. If you have many outlets, this project adds up but the cost is trivial.

Where utilities pierce the house walls—pipes, wires, HVAC ducts—look for gaps around them. This is particularly important where water supply lines enter, around dryer vents, and where ductwork passes through walls or foundations. Caulk small gaps. For larger gaps, use expanding foam. It’s messy and hardens quickly, so work carefully. Follow the instructions and don’t over-apply—expanding foam expands significantly as it cures. Trim excess with a utility knife once it hardens.

In attics and basements, sealing gaps where walls meet ceilings or where walls meet foundations prevents significant air leakage. These aren’t places you spend time but they’re major sources of energy loss. In attics, gaps between wall tops and roof framing allow conditioned air to escape into the attic and the outside. Use caulk or expanding foam. In basements, gaps around rim joists (the frame piece sitting on the foundation) are infamous for air leakage. This is accessible and important to seal.

If you have ductwork visible in an attic, basement, or crawlspace, check it for leaks. You’ll see gaps at joints or obvious holes. Ductwork carries conditioned air. Leaking ducts waste energy. Seal visible leaks with mastic (a putty-like duct sealant) or foil tape. This is straightforward work.

The realistic cost for a DIY project addressing the obvious leaks—doors, windows, outlets, and accessible gaps—runs $100 to $300. The payback comes from reduced heating and cooling costs. In many climates, the energy savings run $100 to $300 annually, so the investment pays for itself in a year or two. If you want to be thorough about identifying the biggest leaks, hire a professional for an energy audit. This costs $200 to $400 but they use thermal imaging and blower door tests to identify exactly where the biggest problems are. That information directs your efforts toward the leaks that actually matter.

Start with the obvious ones. Seal doors and windows. Add outlet gaskets. Caulk and weatherstrip. Work methodically around your house. Most people find they can meaningfully reduce drafts in a weekend with minimal cost. You don’t have to get everything perfect. Even sealing the obvious leaks improves comfort and reduces energy waste. That’s enough to make a real difference.

© The Whole Home Guide