Why draughts matter more than you might think

A draught is really just money leaving the house. An unsealed letterbox, a gap under the back door or an open chimney flue can move a surprising volume of warm air out of a room, and your boiler then has to work harder to replace it. Cold air also arrives at ankle height, which is why a room can feel chilly even with the heating on full.

The good news is that draught-proofing is the cheapest, quickest energy improvement you can make. Most fixes cost a few pounds and take minutes rather than days. Unlike a new boiler or a loft full of insulation, you can work room by room, start with the worst offenders, and feel the difference the same evening. It also makes a house quieter and less dusty, which is a bonus nobody warns you about.

Start at the front door: letterboxes, keyholes and cat flaps

External doors are usually the biggest culprits, and the smallest gaps there cause the most noticeable draughts because the wind hits them directly. Work through this list before you spend anything on bigger jobs.

• Letterboxes: fit a brush-style excluder on the inside face of the door. Brush types cope better with wind than the hinged metal flaps, which can rattle and catch the breeze.
• Keyholes: a spring-loaded cover that swings shut costs a couple of pounds and takes a minute to fit. It stops a steady stream of cold air at chest height, which you will notice immediately.
• Cat flaps: check the flap sits flush and closes fully. A magnetic or close-fitting replacement flap, plus a strip of brush seal around the frame, makes a real difference.
• Door edges: run self-adhesive rubber or foam seal around the frame, and fit a brush strip or wiper seal along the bottom. If the door is warped, adjust the hinges or the latch first, because gaps at the top and sides can be just as costly as one at the floor.

Chimneys: the biggest hole in the house

An open chimney is effectively a hole in your roof, and warm air disappears up it all day. If the fireplace is unused, block it. An inflatable chimney balloon or a wool or foam chimney draught excluder costs roughly £15 to £30 and simply wedges into the flue.

Measure the flue before you buy, and push the blocker up far enough to be out of sight but still reachable. If you ever light a fire, the blocker must come out first, so tie a reminder tag to the fire guard or leave a note in the fireplace. Never block a flue that serves a working gas fire, wood burner or boiler, as those appliances need the flue to draw safely.

If you do use the fireplace, fit a chimney cowl on the pot instead. It reduces down-draughts and keeps rain out without sealing anything.

Windows, doors and the sneaky gaps you forget

Older windows are rarely airtight, but they are usually fixable without replacement.

• Sash windows: fit brush seals into the vertical channels where the sashes slide, and seal the meeting rail in the middle.
• Casement windows: self-adhesive foam or rubber strip around the opening frame works well. Rub a little chalk on the seal, close the window, and you will see exactly where it fails to touch.
• Secondary glazing film: a clear shrink-wrap sheet taped to the frame and tightened with a hairdryer costs very little and lasts a winter. It is ideal for a rented home or a single cold room.
• Frame edges: seal the joint between window frames and the wall with a bead of decorator's caulk or silicone where there is an obvious gap.
• Curtains: floor-length, lined curtains make a measurable difference. Keep them behind radiators rather than draped over the top, so heat still circulates into the room.

While you are at it, check extractor fan outlets, overflow pipes and cables entering the wall. A squirt of sealant or a back-draught shutter on a fan costs almost nothing.

Floors, skirting boards and service pipes

Gaps between floorboards can add up to a constant cold wash across a living room floor. Push foam gap filler or a flexible sealant into the widest gaps, and run a thin bead of decorator's caulk along the top edge of skirting boards where they meet the wall.

Leave air bricks alone, though. Those vents keep the void beneath a suspended timber floor dry and prevent rot, so they must stay clear. The same goes for trickle vents on windows and any permanent ventilation serving a fuel-burning appliance.

Finally, look up. A loft hatch with no seal lets warm air escape all winter. A strip of draught excluder around the frame and an insulated cover over the hatch is a half-hour job with a noticeable payoff.

Seal the draughts, keep the ventilation

Draught-proofing is about stopping uncontrolled air movement, not about making your home airtight. Homes need ventilation to manage moisture and keep indoor air healthy, and sealing too enthusiastically can lead to condensation, damp patches and mould on cold walls.

So keep purpose-provided ventilation working: trickle vents open, air bricks clear, extractor fans in kitchens and bathrooms doing their job. Run the fan for ten to fifteen minutes after a shower or cooking, and open windows wide for five minutes once or twice a day rather than leaving them ajar all afternoon. If you have any fuel-burning appliance, fit a carbon monoxide alarm and test it regularly.

Work through the house in order of impact: front and back doors first, then the chimney, then windows, then floors and loft. A Saturday's effort and perhaps £30 to £50 in materials will make your home warmer, quieter and cheaper to heat, and you can build on it with insulation when you are ready for a bigger job.