You heat or cool the air in your home at real expense, and then a surprising amount of it slips out through gaps you can't see — under doors, around window frames, through an unused chimney, past the letterbox flap. Draught-proofing is the least glamorous energy upgrade there is, and one of the highest-return: it's cheap, most of it needs no tools, and much of it works just as well in a rented flat as an owned house.
The takeaway up front: most of the waste comes from a handful of obvious gaps, and sealing them costs far less than you'd guess. You don't need a blower-door test or a contractor to start. You need an afternoon, a way to find the leaks, and a short list of the fixes that are actually worth doing — plus one hard rule about the vent you must never block.
Why draughts cost more than they feel like
A draught isn't just a cold ankle. Every gap that lets cold air in is also letting the warm air you paid to heat leak out, so your heating runs longer and harder to hold the same temperature. In summer with cooling on, the same gaps work in reverse. Air leakage is one of the biggest sources of wasted energy in a typical home, sitting right alongside insulation — and unlike insulation, you can fix a lot of it yourself this weekend.
It's worth being honest about scale, because this is a niche full of inflated numbers. Nobody can promise you a specific percentage off your bill — it depends on how leaky your home is to start with, your climate, and how you heat. What is reliable is the direction: sealing real draughts lowers the energy you waste, improves comfort immediately, and costs very little. Treat the savings as a welcome bonus and the comfort as the guaranteed win.
Step one: find the leaks before you buy anything
Don't start by buying a bag of weatherstrip. Start by finding where your home actually leaks, because the pattern is different in every house. A few simple detection methods, cheapest first:
- The hand test. On a cold or windy day, run the back of your hand slowly around door frames, window edges, letterboxes, and where pipes or cables enter a wall. Bare skin feels moving air well.
- The candle or incense test. Hold a lit candle, incense stick, or a thin strip of tissue near the same spots. Where the flame or smoke wavers sideways, air is moving through a gap. Keep the flame away from curtains and anything flammable.
- The look for daylight test. In daytime, turn off the lights and look at the edges of exterior doors and window frames. Daylight showing through is a gap you can seal.
- The whole-house trick. On a windy day, close all exterior doors and windows, turn off any combustion appliances, then run a fan in a window blowing outward to lower indoor pressure. This exaggerates draughts and makes the hand and smoke tests far more obvious.
Make a quick list as you go. You'll almost always find that a few spots account for most of the airflow — and those are where your money and effort belong.
The leaks worth sealing, in order
Not every gap is equal. Focus on the big, easy wins before fiddling with tiny ones. Here's a rough priority order and the honest fix for each.
| Where it leaks | Typical fix | Notes |
|---|---|---|
| Under exterior doors | Brush strip or door sweep; a draught excluder "snake" for renters | Biggest single gap in many homes; the snake needs no fixings |
| Around door and window frames | Self-adhesive foam or rubber weatherstrip in the gap | Cheap, DIY, peels off cleanly later — ideal for rentals |
| Letterbox / mail slot | Brush or flap cover | Small opening, constant draught |
| Keyholes and cat flaps | Keyhole cover; insulated flap | Tiny but surprisingly breezy |
| Unused fireplace / chimney | Chimney balloon or removable draught excluder | Only if the fireplace is genuinely out of use |
| Gaps where pipes/cables enter walls | Sealant or expanding foam | Often overlooked; easy with a caulk gun |
| Skirting boards and floorboards | Flexible filler or sealant | Matters most on ground floors over a void |
| Loft hatch | Weatherstrip around the edge + a latch | Warm air escapes upward here |
The pattern underneath the table: seal the moving air, not the whole house. A door sweep and a few metres of weatherstrip fix more than a whole tube of expensive gadgets.
Renter-friendly fixes that leave no marks
If you rent, you can still do most of this — the trick is choosing reversible options and keeping your deposit safe.
- Draught excluder snakes sit along the bottom of doors and windows. No adhesive, no damage, and you take them with you when you move.
- Removable foam and rubber weatherstrip peels away cleanly if you buy the low-tack kind and remove it gently. Test a small piece first on painted trim.
- Chimney balloons and fireplace excluders simply push in and pull out.
- Heavy or thermal curtains cut the chill from leaky windows without touching the frame at all — close them at dusk to trap warmth, open them to daytime sun.
- Rope caulk is a soft, putty-like strip you press into window gaps for the cold season and peel off in spring, leaving no residue.
None of these need a landlord's permission or a single screw. For anything more permanent — caulking frames, fitting fixed brush strips — a quick message to your landlord usually gets a yes, since it improves their property.
The one place you must never seal: ventilation
This is the safety rule, and it matters more than any saving. Do not block deliberate ventilation. Homes need a certain amount of fresh air to stay healthy and, critically, to run fuel-burning appliances safely.
- Leave trickle vents, wall vents, and extractor fans clear. They control moisture and prevent damp and mould.
- Never seal a vent or air brick that supplies a gas boiler, wood stove, open flue, or any combustion appliance. Starving these of air can cause dangerous, and potentially fatal, carbon monoxide build-up.
- Keep bathroom and kitchen ventilation working — sealing a leaky home too tightly without managing moisture just moves the problem to condensation and mould.
If your home has any fuel-burning appliance, fit a working carbon monoxide alarm before you tighten anything up. Draught-proofing targets the accidental gaps around doors and windows — not the vents your home was designed to have. When in doubt about a vent's purpose, leave it and ask a qualified person.
When to stop DIY and call a pro
Most draught-proofing is squarely a DIY job, but a few situations warrant help. If you suspect large leaks you can't locate, a professional blower-door test pressurises the house and pinpoints them precisely — worth it before a bigger retrofit. Gaps around a gas appliance or flue, sealing that might affect an existing extraction or heat-recovery system, or signs of persistent damp and mould all call for a qualified tradesperson rather than a tube of filler. Knowing the line keeps the cheap wins cheap and the risky bits safe.
Draught-proofing pairs naturally with the rest of your home's efficiency: once the leaks are sealed, insulation and an efficient heating setup have less work to do. For the full picture of where a home's energy actually goes, see the energy-efficient home guide; and when a worn-out heater or appliance finally needs replacing, how to choose energy-efficient appliances walks through the running-cost math.
FAQ
How much can draught-proofing actually save me?
There's no honest single figure — it depends on how leaky your home is now, your climate, and how you heat. What's reliable is that sealing genuine draughts reduces wasted energy and improves comfort straight away, for very little money. Judge it by the draught you can no longer feel, not by a headline percentage.
What's the cheapest fix that makes the biggest difference?
Usually the bottom of your exterior doors. A door sweep, brush strip, or even a fabric draught excluder snake blocks one of the largest and windiest gaps in most homes for a few dollars and zero tools.
Can I draught-proof a rental without losing my deposit?
Yes. Stick to reversible options: draught excluder snakes, low-tack or rope caulk on windows, chimney balloons, and thermal curtains. All come out cleanly when you leave. Ask your landlord before doing anything permanent like fixed caulking.
Is it possible to seal a home too tightly?
Yes, and it's a real risk. A home needs fresh air for health and for any fuel-burning appliance to run safely. Never block trickle vents, air bricks, or appliance vents, keep bathroom and kitchen extraction working, and fit a carbon monoxide alarm if you burn gas or wood.
Should I draught-proof or add insulation first?
Draught-proof first — it's cheaper, faster, and much of it is DIY. Sealing air leaks also makes any insulation you add later work better, because insulation slows heat conduction but does little to stop air rushing straight through a gap.
Next step
Draught-proofing is the rare home upgrade that's cheap, quick, and mostly free of trade-offs — as long as you seal the accidental gaps and leave the deliberate vents alone. Spend one afternoon finding your leaks, fix the obvious ones with a few dollars of weatherstrip and a door sweep, and you'll feel the difference the same evening. For more practical, no-greenwashing ways to make your home greener one change at a time, visit Just Green.
