The cheap draught-proofing that pays for itself in a winter
Cold air coming in means warm air going out. The fixes that make the biggest difference cost less than a tank of oil and take an afternoon.
Older houses leak. Cold air comes in low, warm air escapes high, and the boiler makes up the difference. Draught-proofing is not glamorous, but it is the cheapest way to make a house feel warmer at the same thermostat setting.
Work through these in order. Each one is a small job.
1. The letterbox and keyhole
A letterbox is a hole in your front door that stays open all winter. A brush-lined letterbox flap costs a few pounds and fits with two screws. While you are there, a keyhole cover on an old-style lock closes another small hole.
2. Gaps around external doors
Stand inside with the lights off on a bright day. If you can see daylight around the door, air is coming through. Self-adhesive foam or rubber strip along the frame closes the sides and top. A brush strip screwed to the bottom of the door closes the gap underneath.
3. The chimney
An open fireplace that is not in use pulls warm air out of the room and up the flue all day. A chimney balloon or a purpose-made chimney draught excluder blocks it. Take it out before you next light a fire, and label the fireplace so nobody forgets.
4. Floorboards and skirting
In rooms with suspended timber floors, cold air rises between the boards and along the skirting. Flexible filler in the gaps at the skirting, and a rug over the busiest part of the floor, both help more than they sound like they should.
5. Curtains that actually close
Thick, lined curtains, drawn at dusk, keep a surprising amount of heat in. Make sure they hang inside the windowsill or are tucked behind the radiator, otherwise they funnel the radiator's heat straight onto the cold glass.
What to leave alone
Do not seal trickle vents on windows, extractor fans, or the air bricks that ventilate under a timber floor. Those are there to stop damp and to give the boiler the air it needs. The aim is to close the gaps you did not choose, not to stop the house breathing.