DIY draught-proofing

No one likes to live in a draughty house. And apart from the discomfort, it’s a waste of money if the heat you have paid for is escaping through gaps in the house and being replaced by cold air from outside. The good news is that draught proofing is easy. A bit of DIY can go a long way to plugging those gaps and keeping cosy at home. You’ll stop wasting money on your heating bills, and cut down on your carbon dioxide (CO2) emissions too.

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 advice sheet. Use the checklist (below) to find out how you can draught proof different areas of your home.

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.

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

Windows Use foam, metal or plastic draught strips (see below), or brush seals for sash windows
Exterior doors Fit brush or hinged-flap draught excluders, fitted along the bottom of the doors (see below)
Interior doors Cut draughts with ‘snake’ draught excluders (photo, right), brushes or similar strips of material (see below)
Unused chimneys Chimney draught excluders are available from most DIY stores. Plastic bags stuffed with other plastic bags also work – remember to remove and let the air circulate in summer
Floorboards and skirting boards Fill the gaps with flexible fillers, clear or brown silicone mastic, decorators’ caulk or similar products
Cracks in walls Use cement or a hard-setting decorators’ wall-filler
Redundant extractor-fan outlets These should be blocked up
Loft hatches Use strips of draught excluding material fitted around the edges of the frame, and don’t forget to insulate the hatch itself
Around pipework Apply silicone mastic, wall-filler or expanding foam as appropriate
Lighting and electrical fittings Plug the gaps around the fittings with wall-filler
Letterboxes Fit flaps or brushes to keep the cold air out and the warm air in. See over for instructions

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

1) How to fit a door brush 

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!

2) 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.

3) How to seal a window or door using foam-seal

Start by cutting off a 50-60mm piece of the foam draught excluder to use as a test strip. Stick this to the door or window frame (not the door or window itself), as close as possible to the edge nearest you.

Close the door or window and slip a credit 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 or window and cut the excluder to the required lengths using a pair of scissors.

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