Why draught proofing is the cheapest heat you'll ever save

Before you think about new windows or a boiler upgrade, it's worth tackling the gaps. A typical UK home loses a surprising amount of warmth through unsealed cracks around doors, windows, letterboxes and skirting boards. That cold air doesn't just make rooms feel chilly — it forces your heating to work harder for longer, which shows up on your energy bill every month.

The good news is that draught proofing is one of the few home improvements you can genuinely finish in a weekend. Most materials cost a few pounds per door or window, and the difference is often noticeable the same evening. You're not trying to make your house airtight — you're simply stopping the obvious gusts that you can feel with the back of your hand.

Find the draughts before you buy anything

It's easy to guess wrongly about where the cold is coming from, so spend twenty minutes doing a bit of detective work first.

• The hand test: on a cold, windy day, run the back of your hand slowly around door frames, window edges, the letterbox, and where the floor meets the skirting board. You'll feel a distinct coolness where air is moving.
• The candle test: a lit candle or a thin strip of tissue held near a suspected gap will flicker or waft when there's a draught. Never use a flame near curtains or loose fabrics.
• Look for daylight: on a bright day, check around external door frames and loft hatches — if light gets through, so does cold air.
• Check the usual suspects: keyholes, cat flaps, extractor fan surrounds, pipework entering walls, open chimneys, and gaps between floorboards.

Make a quick list room by room. It's far more efficient than wandering around a hardware shop guessing what you might need.

Doors: where most of the cold gets in

External doors are usually the biggest offenders, particularly older timber ones that have shifted over the years.

• Bottom of the door: a brush or rubber seal fitted to the base of the door is cheap and very effective. For uneven floors, a sprung flap seal adjusts as the door moves.
• Sides and top: self-adhesive foam or rubber strips work well on a clean, dry frame. For doors that stick, a thin rubber seal or a brushed strip is a better choice than foam, which can compress and tear.
• Letterboxes: fit a letterbox draught excluder with a brush or flap on both sides. It's a ten-minute job and stops a steady stream of cold air.
• Keyholes: a small keyhole cover with a rotating disc costs very little and seals an obvious gap.
• Internal doors: don't forget them. Sealing the door between a cold hallway and a warm living room keeps heat where you want it.

If your door frame itself has gaps between it and the wall, fill those with a flexible sealant rather than trying to cover them with strips.

Windows, lofts and the awkward spots

Older sash and casement windows are notorious for draughts, but you don't need to replace them to make a difference.

• Sash windows: use a brush or wiper seal in the channels where the sashes slide, plus a thinner seal where the two sashes meet in the middle.
• Casement windows: foam or rubber strips around the opening edge work well. Check the hinges and handles still close properly afterwards.
• Loft hatches: fit a foam or brush strip around the edges of the hatch. Cold air pooling in a loft can find its way down into the house.
• Chimneys: an unused open fireplace is a big hole in your thermal envelope. A chimney balloon or draught excluder stops the draught while remaining removable if you light a fire.
• Floorboards and skirting: gaps between boards can be filled with a flexible wood filler, and a bead of sealant along the skirting will close up the gap against the wall.
• Pipework and cables: seal around pipes entering from outside, and check extractor fans for backdraught shutters that are stuck open.

Don't seal everything — ventilation still matters

This is the part people get wrong. A home needs a certain amount of fresh air, especially where there's a boiler, gas hob, open fire or wood burner. Sealing a room completely can trap moisture, encourage condensation and mould, and in the worst cases interfere with safe combustion.

So leave your trickle vents open, keep bathroom and kitchen extractor fans working, and don't block permanent air bricks. If you have an open-flued appliance, keep the ventilation it needs and consider a carbon monoxide alarm if you don't already have one. In older homes, some background draught is doing a job.

What it costs and what to expect

Most draught proofing materials are inexpensive. A door seal kit might cost a few pounds, a letterbox excluder even less, and a chimney balloon is a small one-off purchase. If you'd rather not do it yourself, a handyperson can usually tackle a whole house in a day.

The savings vary with the size of your home, how leaky it is, and how you heat it, but draught proofing is widely regarded as one of the best-value energy improvements you can make. Combine it with sensible habits — closing curtains at dusk, using thermostatic radiator valves, and setting your heating programme to match when you're actually home — and you'll feel the benefit well before spring.

Start with the worst draught, work through your list, and don't worry about perfection. Even sealing a handful of the leakiest spots will make your home warmer, quieter and cheaper to run this winter.