Draught-proofing your home: the cheapest energy win

Of all the ways to cut heating bills, draught-proofing has the best payback. Materials cost a few pounds or dollars per door or window, the work is within most people's DIY ability, and the improvement is immediate. It also makes every room more comfortable — no more cold feet or that chill in the back of your neck.

Why draughts matter — and why this beats most other upgrades

A draught is uncontrolled cold air entering through gaps you didn't deliberately create. Unlike the ventilation your home needs to breathe safely, draughts don't improve air quality — they just bleed away warmth and run up your heating bill. Sealing them keeps the heat you've already paid for inside, which is exactly what a well-insulated building does.

Draught-proofing is usually cheaper than adding insulation and far cheaper than upgrading heating equipment. For a whole house the materials might cost the same as a modest dinner out, and payback in heating savings typically comes within the first winter. See our energy saving overview for where this sits among other improvements.

Finding the gaps: DIY detection

You don't need specialist equipment to locate draughts. Do this on a cold or windy day for the clearest results.

• The hand test. Move your open hand slowly around door frames, window edges, skirting boards, floorboards and where walls meet ceilings. Cold air is easy to feel.
• The candle or incense stick test. Hold a lit candle or smouldering incense stick near suspected gaps (keep it away from flammable materials). Any flicker or smoke movement shows air flow.
• The torch test. After dark, have someone shine a torch from outside while you look from inside for thin lines of light coming through cracks.

Common gap locations to check:

• Around the frame of exterior doors — top, sides and especially the bottom
• Around window frames and between opening sashes
• Letterboxes and keyholes in front doors
• Floorboards, particularly near external walls
• Gaps behind skirting boards
• The loft hatch (one of the worst offenders)
• Where pipes or cables pass through external walls or floors
• Around an unused fireplace or chimney
• Cat flaps and older dog flaps without good seals

Fixes by location

Doors and windows

• Self-adhesive foam tape (weatherstrip). Compresses when the door or window closes to seal the gap around the frame. Inexpensive and quick to apply; lasts a few years before needing replacement. Choose the right thickness so the door still closes fully.
• V-strip or wiper seals. A thin strip of metal or plastic that springs open to fill the gap. More durable than foam tape and suits gaps that vary in width.
• Brush strip seals. A strip of fine nylon bristles along the door edge or frame. Works well where the gap is uneven or where a door drags — common on older wooden doors that have swollen and shrunk over the years.
• Door bottom seals. A strip fitted to the bottom of the door itself. Options include draught-excluder brushes, automatic drop seals (which lift when the door opens) and simple rubber or silicone strips.
• Fabric draught excluders. The familiar sausage-shaped cushion placed at the base of a door. Needs no fitting and works immediately, though it only seals when in place.

Letterboxes and keyholes

• A letterbox flap or brush seal fitted to the inside of the letterbox cuts the cold air that pours through a standard open slot. Some come as a complete cover with a central brush curtain.
• A keyhole cover (escutcheon plate with a spring-loaded cover) blocks the small but real draught through an old-fashioned keyhole.

Unused chimneys

• An open chimney is essentially a hole in your ceiling drawing warm air out of the room constantly. A chimney balloon (an inflatable stopper placed inside the flue) blocks this airflow when the fire is not in use.
• Alternatively, a sheep's wool chimney draught excluder does the same job and is easy to remove when you want a fire.
• Both must be removed before lighting a fire. Most come with a reminder tag hanging down into the fireplace opening.
• If the chimney is permanently disused, a solid register plate fitted by a builder is a more permanent fix.

Floorboards and skirting

• Gaps between floorboards can be filled with flexible wood filler that moves with the boards rather than cracking. For larger gaps, thin strips of wood (sometimes called slip feathers) can be glued in.
• Gaps between the skirting board and the floor are best sealed with flexible decorator's caulk, which stays soft enough to cope with seasonal movement in the wood.

Pipework, cables and other penetrations

• Where pipes or cables pass through an external wall, gaps around them let cold air in. Fill with silicone sealant or expanding foam (use the low-expansion type near pipes to avoid cracking plasterwork).

Loft hatch

• Stick self-adhesive foam strip around the frame rebate so the hatch compresses it when closed. If the hatch has no insulation on its top face, add a layer of rigid foam board — the hatch itself is often a significant heat loss.

How to seal a door or window — step by step

1. Clean the surface. Wipe the door or window frame thoroughly with a dry cloth to remove dust and grease. Tape and sealant don't stick well to dirty surfaces.
2. Measure the gap. Close the door or window and feel around the frame with your hand. Note which edges have a gap and roughly how wide. For foam tape, the compressed width should match the gap.
3. Choose the right product. Foam tape for most gaps up to about 4 mm; brush strip or V-strip for larger or uneven gaps; a door bottom seal for the threshold.
4. Cut to length and apply. Peel off the backing paper and press the tape firmly along the door stop (the thin strip of wood or frame the door closes against), not along the door itself. Work around the full perimeter.
5. Test the seal. Close the door and check it shuts snugly without needing extra force. Repeat the hand or candle test to confirm the draught has gone.
6. Fit the bottom seal. For the door base, fit a brush strip or drop seal to the door bottom following the product instructions. Check clearance over any threshold or mat.

Balancing draught-proofing with healthy ventilation

A draught-proofed home still needs fresh air — both for the occupants and to prevent condensation and damp. The difference is between accidental gaps (cracks around door frames, gaps in floorboards) and intentional ventilation (trickle vents, extract fans, air bricks).

• Keep trickle vents in window frames open, especially in bedrooms and living rooms.
• Use bathroom and kitchen extractor fans whenever you cook, shower or bathe — this is the main defence against condensation and mould.
• If a room feels stuffy after draught-proofing, open a window for a while rather than unsealing your work.
• In a very tightly sealed home, consider a simple whole-house ventilation system (such as a MVHR unit) if condensation becomes a problem. This is more relevant to new-build or heavily retrofitted homes than most older houses.

For more on managing moisture and air quality after improving your home's airtightness, see our guide on damp and mould.

Your draught-proofing checklist

• Test all external doors with your hand on a cold day and seal any gaps found.
• Fit a brush strip or drop seal to the bottom of every external door.
• Check window frames and add foam tape or V-strip where needed.
• Fit a letterbox brush seal and keyhole cover to the front door.
• Block unused chimneys with a chimney balloon or wool excluder (with reminder tag).
• Fill gaps between floorboards with flexible filler; seal skirting gaps with caulk.
• Seal around any pipe or cable penetrations in external walls.
• Add foam strip and insulation to the loft hatch.
• Confirm trickle vents, air bricks and extractor fans are all still unobstructed.
• If any vent is near a fuel-burning appliance, check with a registered engineer before touching it.