Draught-Proofing: The £30 DIY Fix That Cuts Your Heating Bill by 20%

Your Home Is Leaking Heat (and Money)

Feel a cold breeze near your front door? Notice the curtains moving when the windows are closed? That's draughts — uncontrolled gaps where warm air escapes and cold air enters. Your boiler heats the air, and then it literally leaks out of your house.

The Energy Saving Trust estimates that draught-proofing can save a typical UK home £60 per year on gas bills. For older, draughtier properties, the saving can be significantly higher. Given that the materials cost £20-30 and the work takes an afternoon, the payback period is measured in months, not years.

Draught-proofing is the single highest-return DIY energy improvement you can make.

Where to Find (and Fix) Draughts

External doors — The biggest source of draughts in most homes. Check around the edges of your front and back doors. If you can see daylight around the edges, cold air is getting in.

Fix: Self-adhesive foam strip (£3-5 per door from any hardware store). Clean the door frame, cut the strip to length, peel off the backing, and press it firmly along the frame where the door meets the frame. For the gap at the bottom of the door, fit a brush strip or door sweep (£5-10) — these screw to the bottom of the door and create a seal against the floor.

Windows — Especially sash windows and older casement windows. Check for gaps between the frame and the wall, and between the opening part and the fixed frame.

Fix: Self-adhesive foam or rubber strip for gaps between the opening window and frame. For gaps between the window frame and wall, use decorators' caulk (£3-5 per tube) — apply with a caulk gun and smooth with a wet finger. It's paintable and flexible.

Floorboards — Gaps between floorboards and between skirting boards and floors let cold air rise from the unheated space below.

Fix: Use a flexible filler for small gaps between boards. For larger gaps, push lengths of rope or foam filler rod between the boards. For skirting board gaps, run a bead of decorators' caulk along the joint.

Letterbox — An open letterbox is essentially a rectangle of outside air pointed directly into your hallway.

Fix: A letterbox brush plate (£5-8) fits over the interior side of the letterbox. Bristles block draughts while still allowing post through.

Chimney — If you have an unused open fireplace, it's a massive heat loss point. Warm air rises up and out of the chimney continuously.

Fix: A chimney balloon or chimney sheep (£15-25) sits inside the chimney just above the fireplace opening, blocking the airflow. Remember to remove it before lighting a fire.

The Shopping List

For a typical 3-bed house, you need:

Item	Approx Cost
Self-adhesive foam strip (2 packs)	£6
Door brush strip x 2	£12
Decorators' caulk x 2 tubes	£6
Letterbox brush cover	£6
Total	£30

All available from B&Q, Screwfix, Wickes, or Amazon. No specialist tools needed — a pair of scissors, a caulk gun (£3), and 2-3 hours.

What NOT to Draught-Proof

Do not seal ventilation. Some gaps exist on purpose:

• Trickle vents on windows — These are the small slots at the top of double-glazed windows. They provide controlled ventilation and should stay open. Blocking them can cause condensation and mould.
• Air bricks on external walls — These ventilate under-floor spaces and prevent damp. Never block them.
• Extractor fans in kitchens and bathrooms — These remove moisture. Blocking them leads to mould and poor air quality.
• Rooms with gas appliances — Gas boilers, cookers, and fires need ventilation for safe combustion. Never reduce ventilation in rooms with gas appliances.

The rule: seal uncontrolled draughts (gaps, cracks, poorly fitting doors) but leave controlled ventilation (trickle vents, air bricks, extractor fans) alone.

Beyond DIY: Professional Draught-Proofing

If you have sash windows, professional draught-proofing is worth considering. Companies like Ventrolla specialise in fitting discreet brush strips and compression seals into sash windows without replacing them. The cost is typically £150-300 per window — much cheaper than replacement double glazing — and preserves the character of original windows.

For listed buildings or conservation areas where you can't replace windows, professional draught-proofing of existing sashes is often the best (and sometimes only) option for improving energy efficiency.

The Bigger Picture

Draught-proofing alone won't transform your energy bill, but it stacks with other measures:

1. Draught-proofing — £30 DIY, saves £60+/year
2. Loft insulation — £300-400 (or free via ECO scheme), saves £180+/year
3. Smart thermostat — £150-250, saves £75-150/year
4. LED bulbs — £20-30 for the house, saves £40+/year

Combined, these four measures can reduce household energy spending by £300-400 per year. Draught-proofing is the easiest and cheapest starting point.