DIY Energy-Saving Window/Door Sealing

What it is

Draughts can account for as much as 25% of a home's heat loss, and the gaps responsible are usually small enough to fix in an afternoon for under €20. It is one of the highest-return jobs in the house.

DIY window and door sealing means closing the air leaks that let warm air out and cold air in. The tools are cheap and basic: self-adhesive foam or rubber weatherstripping for the moving edges of windows and doors, a draught excluder along the bottom of a door, and a tube of flexible sealant or caulk for fixed gaps around frames. You feel for the leaks on a windy day, often with a hand or a candle flame that flickers, then seal them one at a time.

The order of attack matters. Hit the biggest, draughtiest gaps first, usually the bottom of an old front door and the sash of a rattling window, because those deliver most of the saving. Fiddling with tiny gaps before sealing a door that whistles is effort spent in the wrong place.

This is genuinely one of the cheapest ways to cut a heating bill. The materials pay for themselves within a heating season in most homes, and the work needs no special skill, just patience and a willingness to feel along edges for moving air. The one caution is ventilation. A home needs some air exchange, especially where there is a gas appliance, so the goal is sealing uncontrolled draughts, not making a room airtight.

How it works

If you can feel a draught with a wet hand or see a candle flame lean near a closed window, you have found your target, and the energy saved comes from sealing those specific leaks, not from wrapping the whole house. A wet hand passed slowly around a window or door frame finds the gaps cold air pours through.

For window and door frame gaps, self-adhesive foam or rubber weatherstrip tape is the fast fix. Clean the surface first with white spirit so it actually sticks, measure the gap, and choose a profile that compresses to fill it, an EPDM rubber V-strip outlasts cheap foam by years because foam crushes flat and stops sealing within a season. Run it along the frame where the moving part closes against it.

For the gap under a door, a brush strip or a draught excluder does the work. A screw-on brush seal across the bottom of an external door handles uneven floors well, while a simple fabric sausage excluder suits internal doors. Letterboxes and keyholes leak more than people realise and take a brush flap and a cover.

For the larger jobs, gaps around skirting, between floorboards, and where pipes pass through walls take a flexible filler or decorator's caulk, which stays slightly elastic and does not crack as the house moves. Old sash windows benefit hugely from sealing the gaps while keeping the cords working.

Benefits

Sustainability Home Improvement Relaxation Problem Solving Energy Savings Enjoyment / Fun

What you need

Here's what to gather before you start. The essentials are marked.

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Caulk gun: Erbauer or Stanley (for frame sealant application)

Everbuild Sika Frame Sealant or UniBond Frame Sealant (for fixed frame gaps)

Wickes P-strip self-adhesive foam tape (for moving window and door edges)

Ronseal No More Drafts Expanding Foam (for larger voids and pipe entry points)

Stormguard Letterbox Brush Seal

Stormguard Rain Deflector or brush-strip door bottom seal

Incense sticks or thin tissue paper (for the draft audit)

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Assorted craft paper pack

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Craft knife and sandpaper (for surface preparation)

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Craft knife

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FAQs

How do I find where the draughts are actually coming in?

Hold a lit candle or an incense stick near the edges of windows and doors on a windy day. Where the flame or smoke flickers sideways, you have an air leak. The usual culprits are the bottom of doors, window sashes, and where pipes pass through walls. Check the loft hatch too, since warm air escapes upward.

What's the difference between weatherstripping and caulk?

Movement. Weatherstripping seals gaps around things that open and close, like doors and opening windows, using a compressible strip that still lets the part move. Caulk seals fixed gaps that never move, like the join between a window frame and the wall. Using caulk on a moving part glues it shut, so match the product to the gap.

How much can sealing draughts really save?

Often 10 to 15% off heating costs, sometimes more in a draughty older home. Air leaks are one of the biggest sources of wasted heat, and sealing them is cheap. A roll of self-adhesive foam weatherstrip costs a few euros and a tube of caulk about the same, so the payback is usually within a single winter.

What's the easiest fix for a draughty door?

A draught excluder at the bottom and foam strip around the frame. The gap under the door is usually the worst offender. A brush strip that screws to the bottom of the door handles it permanently, while a fabric draught snake is the no-tools option. Add adhesive foam strip around the frame where the door meets it.

Can I seal windows without making them impossible to open?

Yes, with the right method. For windows you still want to open, use removable rope caulk or foam strip that compresses when shut and releases when opened. For windows you never open in winter, a shrink-film insulation kit (applied with a hairdryer) adds an extra air layer and peels off cleanly in spring. Keep at least one window operable per room for ventilation.