Draught Proofing on a Budget: What £50 Buys Before the First Hard Frost
The cheapest heating upgrade you’ll buy this winter comes in a blister pack and costs about the same as a takeaway. It won’t make any noise, it won’t have an app, and nobody’s going to compliment it. But draught proofing on a budget still does more per pound than almost anything else on the heating-bill shelf, and most British homes built before about 1990 are leaking warm air somewhere you haven’t looked.
In This Article
- Draught proofing on a budget starts with a smoke test
- The £50 shopping list
- Sash windows: brush strips beat foam tape
- Doors, letterboxes and keyholes: the boring bit that matters
- Chimneys and floorboards, the ones people ignore
- What not to seal
- If you only have one afternoon
- What I'd skip
- What you'll notice, and what you won't
I’ll be upfront about one thing. I’m not going to promise you a figure for how much you’ll save, because it varies wildly with the house, and anyone quoting a precise number without seeing your windows is guessing. What I can do is show you where the leaks tend to be, what the fixes cost, and which ones are a waste of time.
Draught proofing on a budget starts with a smoke test
Don’t buy anything yet. Spend ten minutes finding the leaks first, or you’ll end up with a drawer full of foam strip and a hall that’s still freezing.
Pick a cold, breezy day and close every window and external door. Light an incense stick (not a candle, and certainly not a lighter held next to your curtains) and move it slowly around the edges of each window and door, past the letterbox, along the skirting boards and round any pipes that go through the wall. Where the smoke wobbles sideways or gets pulled in a line, you’ve got a draught. The back of a wet hand works too, and it’s less fiddly than it sounds.
Make a list. I’d write it down, because by the third room you’ll have forgotten the first.
The usual suspects, in roughly the order I find them: gaps under the front and back doors, letterboxes, keyholes, sash window meeting rails and sides, loose-fitting casement windows, the chimney in any room you don’t use the fire in, floorboard gaps on the ground floor, the loft hatch, and the holes where pipes or cables go through external walls. A typical Victorian terrace manages most of that list. A 1970s semi usually hits half of it.
The £50 shopping list
Here’s a basket that covers a normal two-up, two-down for around £50. The prices are what I’d expect to pay at a DIY chain or on Amazon, give or take a few quid, because they shift and shops run offers all the time.
A door-bottom brush strip for the front door, about £8. A letterbox brush or flap, about £8. Keyhole covers, about £3 for a pack. A roll of self-adhesive foam or rubber seal for the frames of casement windows and the back door, about £7. Two tubes of decorators’ caulk (the paintable acrylic sort) for the cracks along skirting boards and around window frames, about £8 for both. And a clear window insulation film kit for the one or two windows you can’t otherwise fix, about £16.
That’s £50. And I’d stop there for the first weekend.
If you’re renting, swap the caulk and any screwed-on strips for the stick-on versions and ask your landlord before you drill anything. Most of this is removable. A letterbox brush clipped to the inside of the flap leaves no marks at all.
Sash windows: brush strips beat foam tape
Here’s the opinionated bit. If you’ve got sash windows, ignore the cheap foam tape that’s sold for them. It looks perfect in the packet, it compresses to nothing within a season, and it makes the window stick so badly that you stop opening it.
What works is a brush or pile strip, fitted into a groove or stuck along the channel the sash runs in, plus a brush or compression seal along the meeting rail where the two sashes come together. It takes about an hour a window and it keeps working because the sash can still slide. Historic England publishes guidance on draught-proofing older windows, and the general message is that sealing the gaps is far kinder to the building than ripping the windows out. That’s worth knowing if you’re in a conservation area, where replacing them may not even be allowed.
Does it look as neat as a double-glazed unit? No. Will it cost a fraction of the price? Easily. If a quote for sash window replacement has landed on your doormat and made you feel faint, a few brush strips and a tube of caulk are a respectable stopgap while you think about it.
Doors, letterboxes and keyholes: the boring bit that matters
A front door is the single biggest hole in many homes. You’ve got a gap under it, a hole through the middle of it, and a keyhole that was built before central heating existed.
The door-bottom brush is the best £8 in the basket. Measure the width of the door, buy a strip that’s slightly longer, and cut it to fit with a hacksaw. Screw it to the inside bottom edge of the door so the bristles brush the floor. If the floor is uneven, the bristles forgive it where a rigid rubber strip wouldn’t.
Letterboxes are harder to love. A brush insert inside the flap stops the wind but also fights the post, and thick bundles of leaflets sometimes snag. I’d still fit one. The alternative, for homes where nobody actually uses the front door, is an external post box and a sealed letterbox, which is a bigger job but a permanent fix.
Keyhole covers are daft little swinging discs, and they work. Fit one on the inside of every external door that has an old-fashioned keyhole and forget about it. It’s a two-minute job and the cost is practically nothing.
Chimneys and floorboards, the ones people ignore
If you have an open fireplace you never light, that’s a hole to the sky. Cold air falls down it and warm air leaves up it, and it’s probably the largest uncontrolled gap in the room. The cheap fix is a chimney balloon, an inflatable plug that sits in the flue, typically £20 to £35. The expensive fix is a fitted cap or register plate, which is a job for a professional.
Be careful here. A chimney balloon is for a fireplace that you aren’t using. Take it out before you light anything, and a lot of people stick a reminder note on the fire surround. If you’re thinking of lighting the fire, or you’ve got a gas fire connected to that flue, don’t block it without checking with a registered engineer. I covered the practical side of solid fuel in our log burner rules guide.
Floorboards are fiddlier. In an older house with suspended timber floors, the gaps between boards and between the boards and the skirting let air in from the void below. You can buy rope-style gap sealers and flexible filler for the job, and they’re not expensive, but a thick rug with a decent underlay does a surprising amount of the same job for a room you can’t be bothered to tackle properly. Just don’t block the air bricks on the outside wall. Those keep the timber underneath dry, and sealing them is a good way to grow rot.
What not to seal
This is the part that ends up on forums with a cautionary tone, so I’ll keep it blunt.
Don’t block trickle vents on windows, extractor fans in kitchens and bathrooms, or any vent that feeds a gas boiler, a gas fire or a wood burner. Those appliances need air to burn safely, and starving them can produce carbon monoxide. If you’ve got any gas appliance in the house, you need a working carbon monoxide alarm whether or not you ever touch a draught strip. They’re cheap, and they’re a good deal more useful than any gadget I’ve mentioned so far.
And think about moisture. A leaky house dries itself out by accident. Once you’ve sealed it, the air from showers, cooking and drying washing has fewer places to go, and you may start seeing condensation on windows and black spots in corners. Open a window for a few minutes after a shower, run the extractor, and keep an eye on the cold corners of north-facing rooms. If condensation starts getting out of hand, a dehumidifier is a better answer than ripping the strips off again, and our guide to the best dehumidifiers for damp covers the options.
If you only have one afternoon
Time is tighter than money for most people, so here’s the order I’d work in. Start with the front door, because it’s the biggest single leak and the three fixes (brush strip, letterbox brush, keyhole cover) take well under an hour between them. Then do the back door or whatever door leads to the garden or utility room.
Next, the rooms you actually sit in. Do the living room windows before the spare bedroom, and the bedroom you sleep in before the one that’s full of boxes. A draught on the back of your neck at the sofa costs you more in turned-up thermostat than a draught in a room you only walk through.
Floors and chimneys come after that, partly because they take longer and partly because they’re the ones where it’s easiest to get something wrong. And the loft hatch is worth ten minutes at any point: a self-adhesive foam strip round the frame, and a bit of insulation stuck to the top of the hatch itself, stops the warmest air in the house drifting straight upstairs and out. Nobody ever bothers, which is exactly why it makes the list.
What I’d skip
The contrarian position of the week: plenty of people who are worried about heating bills reach for smart radiator valves or a new thermostat before they’ve fitted a single draught strip. That’s backwards. A controller can only manage the heat you’re making. It can’t stop the heat you’ve made from walking out under the front door. If you’ve got £50 to spend, spend it on the basket above, and look at our energy-saving gadgets piece afterwards for the gadgets that are worth having.
I’d also skip the thick draught-excluder sausage for doors. It’s a decent short-term fix and it’s mildly charming, but it moves, it gets kicked, and it’s often left behind the door in the one place it’s useless. Fit a brush strip and be done with it.
Thermal curtains are the exception to my “skip it” instinct. They’re not draught proofing in the strictest sense, but a lined curtain over a leaky window does soften the cold and makes the room feel warmer, and they look better than window film. Our curtain trends piece covers fabrics that do both jobs.
What you’ll notice, and what you won’t
Honest expectations. You won’tice the front hall stops feeling like a wind tunnel. You’ll feel it round your ankles in the living room, where cold air tends to creep along the floor. You’ll probably hear less noise from the street, which is a nice bonus.
You won’t notice a sudden drop on the bill, because that’s not how it works. The effect is gradual, mixed up with the weather and your own habits, and it takes a full month or two to see in the numbers. If you have a smart meter, check the daily usage on a cold evening before you start, and again a few weeks after. That’s the only fair comparison.
And it won’t replace insulation. Loft insulation, cavity wall insulation and a decent boiler all do bigger jobs. But those are costly and take planning, and draught proofing is a Saturday morning and a screwdriver. For the days in between, a good electric blanket is the cheapest comfort you can buy, which is why we rated them in our best electric blanket guide, and the cheapest electric heater to run is worth knowing about for the one room you can’t get warm.
For the maths on what each measure typically saves, the Energy Saving Trust is the place to start, and Which? publishes home energy advice that’s free to read in places. Check both before you believe any headline figure, including mine, because I haven’t given you one.
So which room in your house is the coldest, and where do you think the air’s actually getting in?
