If you live in a period property, you'll know the feeling: the heating goes on, the radiators warm up, and yet there's still a cold stream of air curling around your ankles. That isn't a failure of your boiler. It's the simple physics of a home built before anyone worried much about airtightness. Victorian and Edwardian houses — and plenty of interwar stock too — were designed to breathe through their fabric: open chimneys, suspended timber floors and loosely fitting sash windows all play a part.
Plugging those gaps is one of the most rewarding jobs you can do. The materials are inexpensive, often just a few pounds per window or door, and most of the work can be done in an afternoon with nothing more exotic than a tape measure and a pair of scissors. You'll feel the difference straight away, and you may find you can turn the thermostat down a degree or two, which adds up handsomely over a winter.
Doors account for a surprising share of heat loss because the gaps around them are large and usually run the full height of the frame.
Before you shop, measure each gap in millimetres. Foam tape comes in several thicknesses, and there's nothing worse than buying a roll that's too thick to let the door close, or too thin to do anything useful.
Sash windows are lovely and leaky in equal measure. The draught usually comes from three places: between the two sashes where they meet in the middle, around the outer frame, and through the gap where the sashes slide up and down.
For the meeting rail in the middle, a dual brush or fin seal fitted to the top of the lower sash works well. For the sides, V-strip or springy metal seals are the traditional choice, because they compress when the window slides and spring back when it's closed. Self-adhesive foam tape is fine for fixed casements, but it can jam a sliding sash or wear away quickly, so think twice about using it there.
If your windows are single glazed and replacement isn't on the cards, cheap secondary glazing film fitted over the frame each autumn will cut both draughts and condensation noticeably. Just make sure you leave at least one window in every room openable for ventilation.
In homes with suspended timber floors, cold air from the void beneath the house finds its way up between the boards. On a windy day you can often feel it by holding a hand near the floor.
A word of caution: if you have air bricks or ventilation slots in the walls near floor level, leave them alone. They keep the timber floor structure dry, and blocking them to stop a draught will cause far more expensive problems later.
An open chimney is essentially a permanent hole in your ceiling. If the fireplace isn't in use, a chimney draught excluder — a balloon or a stuffed cushion that sits inside the flue — stops an enormous amount of warm air escaping upwards. Remove it before you light a fire, and never use one in a chimney that serves a working boiler or gas appliance.
Then walk around the house looking for the less obvious gaps:
There's a balance to strike. An older house needs some ventilation to manage moisture and to keep any gas or solid fuel appliance safe, so the aim is to control air movement, not eliminate it entirely. Never block air bricks, trickle vents, or the permanent vents that serve a boiler, stove or open fire.
Once your main draughts are sealed, you may notice condensation appearing on cold surfaces such as single glazing. That's a sign the moisture has nowhere to go. Open a window for ten minutes in the morning, use extractor fans when cooking and bathing, and keep a background vent open in rooms with a fire. Do that, and you'll have a warmer, calmer house without the damp that comes from sealing everything far too tightly.
Nimble Hearth shares practical, down-to-earth guidance on practical home comfort and efficient living for small uk homes for readers across the UK.
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