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DIY draught-proofing

A home-made draught-excluder on a windowsill.

Draught-proofing is one of the cheapest and most effective ways to save energy and money in your home. Our handy guide explains how…

Updated in October 2022

Draughty homes are uncomfortable. It’s also a waste of money if the heat that you’ve paid for escapes through gaps and cold air comes whistling in from outside. The good news is that draught-proofing is easy and our DIY draught-proofing guide will help you plug those gaps and stay cosy at home.

So, where do the draughts come from?

Most houses, particularly old ones, have cracks and gaps through which warm air goes out and cold air blows in. Not all of these can be dealt with by a DIY-er, but many can, such as the gaps between or around floorboards; around windows and doors; through the letterbox; where pipework comes through external walls; around the loft hatch; and around electrical fittings.

For more information about draught-proofing windows, see our secondary glazing page.

Note: Never block boiler flues, air bricks, or window trickle vents and avoid over draught-proofing windows in kitchens and bathrooms where the moist air needs to escape and where there is no mechanical ventilation like an extractor fan.

Mind the gap

The most common draught zones, and DIY solutions to dealing with them.

Use foam, metal or plastic draught strips (see below), or brush seals for sash windows.
Exterior doorsFit brush or hinged-flap draught excluders, fitted along the bottom of the doors (see over).
Interior doorsCut draughts with ‘snake’ draught excluders (photo, right), or similar strips of material (see over). Note that this should only be a temporary measure – while you’re trying to keep warm. Airflow between rooms is good for a home as it reduces the risk of moist air getting trapped in a particular rooms.
Unused chimneysChimney draught excluders are available from most DIY stores. Plastic bags stuffed with other plastic bags also work – but remember to remove it in summer to let the air circulate.
Around pipeworkApply silicone mastic, wall-filler or expanding foam as appropriate.
Floorboards and skirting boards:Fill the gaps with flexible fillers, clear or brown silicone mastic, decorators’ caulk or similar products.
Cracks in wallsUse cement or a hard-setting decorators’ wall-filler.
Redundant extractor fan outletsThese should be blocked up. This can be done with expanding foam and should then be covered over internally and externally. This can be done with vent covers or by adding plasterboard internally and matching the look of the external wall.
Loft hatchesFit strips of draught-excluder around the edges of the frame, and don’t forget to insulate the hatch itself with fibrous or solid board insulation
Lighting and electrical fittingsPlug the gaps around the fittings with wall-filler.
LetterboxesFit flaps or brushes to keep the cold air out and the warm air in (see below).

Dodge the draught

DIY instructions for three of the simplest but most effective draught-busting techniques …

How to fit a door brush

Fitting a draught-excluding brush to the foot of an interior door.

First, use a tape measure to measure the width of the door and cut the brush to the right length (a hacksaw is good for doing this).

Then position the brush against the door so that the brush is just touching the floor. Using a pencil, make guide marks on the door through the pre-drilled holes in the excluder to show where the screws will go.

Next drill pilot holes in the points you marked and loosely screw the excluder in place.
Open and close the door to ensure it creates a good seal before tightening the screws or adjusting the height if necessary. The excluder should not be placed so low that it makes it difficult to open or close the door!

How to fit a letterbox draught-excluder

First, place the draught-excluder over your letterbox and use a pencil to mark the fixing points through the pre-drilled holes. Maybe a friend could hold the draught-excluder in place while you check that letters can pass through it.

Drill pilot holes at the points you marked and loosely screw the draught-excluder onto the door.
Check that letters can pass through the brushes before tightening the screws, adjusting its position if necessary.

Fixing a perimeter seal around a window or door using foam draught-excluder

Foam draught-excluder strips come in different thicknesses, and it’s important to get the right thickness otherwise either your door won’t close properly, or the draught excluder won’t exclude the draughts.

Ideally you need a short length – about 50mm – to use as a test strip. Stick this to the door frame (not the door itself), as close as possible to the edge nearest you.

Close the door and slip a plastic card between the test strip and the door. It should be a comfortable fit. If you have to force it, then the excluder is probably too thick; if the credit card is loose and falls out, then the excluder is probably too thin. Once you’ve done the test, remove the test strip.

When you’re satisfied that you have the right thickness of foam excluder, measure the frame of your door and cut the foam strip to the required lengths.

Clean and dry the door frame to ensure the adhesive sticks properly, then apply to the door frame, as near to the edge as possible, checking that it isn’t difficult to open or close the door.

You can use exactly the same technique to seal a window using a foam seal.

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