Draught-proofing: the cheapest fixes first

KiloWise editorial team · Last updated 5 November 2026 · Category: Insulation & Draughts

Draught proofing a house — draft proofing, if you are in the US — is the cheapest place to start cutting heat loss. A draught is cold air getting in through a gap, and warm air getting out through the same gap. It is not the same as heat escaping through a wall or a roof: that is insulation's job. Draught-proofing stops air moving; insulation slows heat moving. Both matter, but draught-proofing is cheaper, faster, and usually the first thing worth doing.

This guide ranks the cheapest fixes first, starting with finding the draughts, and ends with what renters can do without asking a landlord. It quotes no prices: costs vary by shop, country, and the size of your home, so wherever a cost matters, use your own quote and run it through the payback checker to see whether the fix pays for itself on your bill.

How to find draughts in your home

Start on a cold, windy day if you can. Close all the windows and outside doors, turn off extractor fans, and walk slowly around the outside walls of each room, holding the back of your hand a few centimetres from the edges of doors and windows, around skirting boards, and near the loft hatch. The back of your hand is more sensitive to moving air than your palm. Mark every spot where you feel a cold stream with a small piece of painter's tape so you can come back to it with the right fix.

Three simple tests help you confirm what your hand tells you. The hand test is the first and the most reliable for a quick pass: if you can feel moving air, there is a gap worth sealing. The candle test — holding a lit candle or a stick of incense near a suspected gap and watching the flame or smoke lean — shows you the direction of the air movement. The paper test works on doors and windows that close against a frame: close a sheet of paper in the door or window, then pull it. If it slides out easily, the seal is loose; if it grips, the seal is doing its job. Test at several points around the frame, because a door can seal well at the top and leak badly at the bottom.

Each test has limits. The hand test only finds draughts strong enough to feel — but those are the ones worth fixing first. The candle test is useless on a still day, and a naked flame near curtains or loose paper is a fire risk, so keep it away from anything flammable and never leave it unattended. The paper test tells you about the seal at one point on the frame, not about gaps elsewhere. None of these tests measures how much energy a draught costs you. For that you need your own numbers — your bill, your heating cost, and the price of the fix — run through the insulation payback checker, which accepts any quoted cost.

Check the usual suspects in this order: the front and back doors, then windows, then the letterbox and keyhole, then the loft hatch, then less obvious spots such as gaps around pipes where they enter the house and the edges of skirting boards on outside walls. In flats, also check the front door to the communal hallway. Work room by room and write down what you find; the list becomes your shopping list.

The cheapest fixes, in order

The order below is cheapest and easiest first. Do them in this order and you will have stopped the worst draughts before you spend anything significant. Stop after each step and re-test with your hand: if a room no longer feels draughty, you are done with that room. One warning: a home still needs to breathe — leave trickle vents, extractor fans, and loft ventilation alone, and if your home already has damp or condensation, deal with that first and ask a qualified professional before sealing anything.

1. Close the gaps you already have

Before buying anything, check whether the draught is a maintenance problem rather than a sealing problem. A door that has dropped on its hinges, a window latch that no longer pulls the frame tight, or a letterbox flap whose spring has gone will leak air no matter how much seal you add. Tightening a hinge screw, adjusting a latch, or replacing a worn spring costs nothing and can close a gap completely.

2. Brush strips and seals for doors

The bottom of a door is usually the worst single draught in a home, because the gap under it runs the full width of the door and sits at floor level where cold air pools. A brush strip or rubber seal fitted to the bottom of the door blocks it. A draught excluder — the long cushion or tube that sits against the bottom of the door — does the same job without any fitting at all, and it is the easiest option for a renter. For the sides and top of a door frame, self-adhesive foam or rubber compression strips press against the door when it closes. The seal must compress slightly when the door shuts: if it does not touch the door, it is sealing nothing.

3. Window seals and secondary glazing film

Windows leak around the frame where the opening part meets the fixed part, and through gaps between the frame and the wall. Self-adhesive foam or rubber strips on the opening frame fix the first kind; a bead of sealant, applied when the weather is dry, fixes the second. Old single-glazed windows also lose heat through the glass itself, which is an insulation problem, not a draught problem — but a cheap sheet of secondary glazing film, stretched over the frame and shrunk tight with a hairdryer, adds a still layer of air and cuts both the draught and some of the heat loss. It is removable, so it suits renters. Do not seal trickle vents — the small slots at the top of modern window frames — because they are the room's deliberate ventilation.

4. Letterboxes, keyholes and cat flaps

A letterbox is a hole in your front door, and an unsealed one is an open invitation to cold air. A brush or flap cover on the inside, plus a seal around the frame, closes it while still letting post through. A keyhole can be covered with a small metal escutcheon or a simple flap that swings aside when the key goes in. A cat flap that does not seal is a small open door: a brush-sealed or magnetic flap that pulls itself shut cuts the draught while still letting the cat through.

5. The loft hatch

The loft hatch is easy to forget and easy to fix. Warm air rises, so a gap around the hatch is a direct route for warm air into a cold loft. A strip of compression seal around the hatch frame, plus a piece of insulation board on the back of the hatch itself if the hatch is thin, stops most of it. Do not block any loft ventilation at the eaves — that ventilation keeps the roof structure dry.

6. Gaps around pipes, skirting boards and floorboards

Once the doors, windows, letterbox and hatch are done, check the smaller gaps. Where pipes pass through outside walls, a ring of sealant closes the hole. Gaps between skirting boards and the floor on outside walls can be sealed with a flexible filler. In older homes with suspended timber floors, gaps between floorboards let cold air up from below; a rug over the worst area helps, but full floor sealing is a bigger job and belongs with the insulation work in our guide to what insulation pays back first.

Draught-proofing vs insulation: do not mix them up

Draught-proofing and insulation solve different problems, and confusing them is the most common reason people spend money in the wrong place. A draught is air moving through a gap. Insulation is heat moving through solid material — a wall, a roof, a floor. Sealing a gap stops the air; insulating a wall slows the heat. A well-insulated house with leaky windows will still feel cold, because the air is moving.

The practical rule is simple: seal first, insulate second. Draught-proofing is cheaper, it needs no permission in most cases, and you can do it in an afternoon. Insulation is the bigger spend, and it is worth ranking by payback before you commit — which is exactly what our guide to what insulation pays back first does.

What renters can do without permission

Almost everything in this guide is renter-friendly, because almost nothing in it changes the building permanently. A draught excluder cushion needs no fitting at all. Self-adhesive foam and rubber strips peel off when you leave, though you should check that they do not take paint with them — test one in an inconspicuous spot first. Secondary glazing film is held on with double-sided tape and peels away cleanly. A letterbox brush cover usually screws on, so ask the landlord before fitting one, or use a draught excluder on the inside of the door instead.

The things that do need a landlord's agreement are the ones that alter the fabric: drilling a brush strip into a door, applying sealant to gaps in the wall, or replacing a letterbox. For those, write to the landlord with a short note — what the draught is, what the fix costs (your quote), and that it can be removed or left in place when you go. Many landlords say yes quickly, because a warmer flat has fewer damp and condensation complaints. Our renter guide, energy saving for renters, covers the full set of no-permission fixes beyond draught-proofing.

Checking whether it worked

After each fix, repeat the hand test at the same spot, on a similar day if you can. The draught should be gone or clearly weaker. The real check is on your bill over the next few months, but a bill is a noisy measure — the weather changes, and so does how much time you spend at home. A cleaner check is comfort: the room holds its temperature longer after the heating goes off. If a room still feels draughty, the air may be coming from somewhere you have not checked — the floorboards, a disused chimney, or an extractor fan with no backdraught shutter.

Keep your notes from the first walk-around and add what you fixed and what it cost (your quote). That record tells you what to check again next winter, because foam strips compress and wear over time, and it gives you the numbers to run through the payback checker when you move on to the bigger jobs. Start with the draughts you can feel, in the order in this guide, and let the whole-home energy audit tell you what to tackle next.

Related: run your own numbers in the insulation payback checker, then read what insulation pays back first and the whole-home energy audit to plan your next step.

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