Draught-proofing: the $30 heating upgrade (Australia)

We recently priced every heater per hour of warmth — but whatever you run, some of that warmth is leaking straight outside through gaps you’ve stopped noticing. Sealing them is the cheapest heating upgrade in existence: 10–20% off your heating and cooling loads, for tens of dollars and an afternoon.

That’s the whole pitch. Here’s the how.

Where the leaks actually are

An average older Australian home leaks from places you walk past every day:

• External doors — the gap under the front and back door is often the single biggest leak in the house. If you can see daylight under it, you’re heating the street.
• The unused fireplace — an open chimney flue is like leaving a window open all winter. If you never light it, close the damper; if there’s no damper, a chimney balloon is about $30.
• Windows — old sashes and sliders rattle for a reason.
• Floorboards and skirting — polished boards on stumps are beautiful and breezy.
• Architraves, cornices, pipe penetrations — small individually, dozens of metres of gap collectively.
• Exhaust fans and vents — many older bathroom fans are open holes to the roof when off.

How to find them (tonight, free)

Wait for a cold, ideally windy evening, turn the heating on, and walk the house with the back of your hand — it’s surprisingly sensitive to moving cold air. Trace door edges, window frames, skirting boards, power points on external walls. An incense stick does the same job visibly: where the smoke kicks sideways, you’ve found money leaving the building.

What to buy (all hardware-store stuff)

Fix	Cost	Skill needed
Door seal / weather strip (bottom of external doors)	~$10–20 per door	Screwdriver
Draught snake (renter-friendly, zero install)	~$10	None
Adhesive foam/rubber strips for windows	~$5–15 per window	Peel and stick
Gap sealant for skirting/architraves/floorboards	~$10–20 a tube	Caulking gun
Chimney damper closed / chimney balloon	$0 / ~$30	None

A whole-house pass typically lands between $30 and $100. Against 10–20% of the heating that dominates a winter bill, that typically pays for itself inside a single winter — there is no upgrade in the guide with better economics, which is why it’s flagged there as the easy win to do before anything with a price tag.

Two honest notes

Renters: this one’s actually yours. Draught snakes, removable adhesive strips and a chimney balloon need no permission and move out with you. When we priced the heaters, most of the big fixes belonged to owners — this is the one that doesn’t.

Don’t seal yourself into a jar. Homes need some fresh air, and gas appliances need ventilation to burn safely. Seal the accidental gaps (doors, windows, floors, unused flues) — never the deliberate ones (wall vents in rooms with gas heaters or unflued appliances, and any ventilation required for them).

The bigger picture

Draught-proofing is half of the envelope story — insulation is the other half, cutting 20–30% of heating effort through the ceiling alone, with the full costs and paybacks priced in the guide. And if you’re not sure heating is even your problem, check your bill against similar homes first — it’ll tell you whether to point this energy at heating, hot water, or your rate.

The 10–20% load reduction and insulation figures are the sourced assumptions from the Decode Energy Home Energy Saving Guide (AU 2026 edition). Hardware prices are typical retail ranges — your Bunnings run may vary.