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Draught-proofing is one of the cheapest and most efficient ways to save energy – and money – in any type of building.
Both draughts and ventilation let fresh air into your home, but good ventilation helps reduce condensation and damp. Draughts are uncontrolled: they let in too much cold air and waste too much heat.
To draught-proof your home you should block up unwanted gaps that let cold air in and warm air out. Saving warm air means you’ll use less energy to heat your home, so you'll save money as well as making your home snug and pleasant.
How much could you save by draught-proofing?
Draught-proofing around windows and doors could save you £25 to £50 per year. Draught-free homes are comfortable at lower temperatures – so you’ll be able to turn down your thermostat. This could save you another 10 per cent off your heating bill.
Where to look for draughts
Draughts happen where there are unwanted gaps in the construction of your home, and where openings are left uncovered.
You’ll find draughts at any accidental gap in your home that leads outside, such as:
- doors – including keyholes and letterboxes
- loft hatches
- electrical fittings on walls and ceilings
- suspended floorboards
- pipework leading outside
- ceiling-to-wall joints
You should block most of these – but be careful in areas that need good ventilation, such as:
- areas where there are open fires or open flues
- rooms where a lot of moisture is produced, such as the kitchens, bathrooms and utility rooms
DIY or professional?
- DIY draught-proofing typically costs between £120 to £290 for materials for your whole house.
- Professional draught-proofing might cost double this amount.
If you’re happy carrying out simple DIY tasks, draught-proofing will be no problem. However, some homes, especially older homes with single glazing, will be more difficult to draught-proof. Professional draught-proofing is likely to save more energy because the installer will know exactly the right materials to use and where to use them.
There are plenty of DIY stores that sell draught-proofing materials, but look for draught-proofing with a Kitemark – this shows that the product is made to a good standard. British Standard Institution accredited products have a 20-year life when correctly installed and maintained.
For windows that open, buy draught-proofing strips to stick around the window frame and fill the gap between the window and the frame. There are two types:
- Self-adhesive foam strips – cheap, and easy to install, but may not last long.
- Metal or plastic strips with brushes or wipers attached – long-lasting, but cost a little more.
Make sure the strip is the right size to fill the gap in your window. If the strip is too big it will get crushed and you may not be able to close the window. If it's too small there will still be a gap.
For sliding sash windows, foam strips do not work well. It’s best to fit brush strips or consult a professional. For windows that don't open, use a silicone sealant.
Draught-proofing outside doors can save a lot of heat and will only cost you a few pounds. There are four main things to consider.
- Keyhole – buy a purpose-made cover that drops a metal disc over the keyhole.
- Letterbox – use a letterbox flap or brush, but remember to measure your letterbox before you buy.
- Gap at the bottom – use a brush or hinged flap draught excluder.
- Gaps around the edges – fit foam, brush or wiper strips like those used for windows.
Inside doors need draught-proofing if they lead to a room you don’t normally heat, such as your spare room or kitchen. Keep those doors closed to stop the cold air from moving into the rest of the house. If there is a gap at the bottom of the door, block it with a draught excluder – you can make one stuffed with used plastic bags or bits of spare material.
Inside doors between two heated rooms don’t need draught-proofing, as you don’t lose energy when warm air circulates.
Chimneys and fireplaces
If you don’t use your fireplace, your chimney is probably a source of unnecessary draughts. There are two main ways to draught-proof a chimney:
- Fit a cap over the chimney pot – this might be better done by a professional; or
- buy a chimney draught excluder – devices that help stop draughts and heat loss through the chimney, usually fitted within the chimney or around the fireplace.
Remember to remove the draught-proofing if you decide to light a fire!
Floorboards and skirting boards
You can block cracks by squirting filler into the gaps. Floorboards and skirting boards often contract, expand or move slightly with everyday use, so you should use a filler that can tolerate movement – these are usually silicone-based. Look for the following:
- Flexible fillers.
- Decorator’s caulk.
- Mastic-type products.
Fillers come in different colours, and for indoor and outdoor use. They block gaps permanently so be careful when you apply them – wipe off any excess with a damp cloth before it dries. Fillers may break down over time, but can easily be reapplied.
Check whether you also need to insulate between the skirting board and the floor.
Hot air rises and gets lost into the cold space in your loft or attic, so it’s worth blocking off draughts around your loft hatch. Use strip insulation, as you would on a door.
You can fill small gaps around pipework with silicone fillers, similar to the fillers used for skirting boards and floorboards. Fill larger gaps with expanding polyurethane foam. This is sprayed into the gap, expands as it dries, and sets hard.
Old extractor fans
Old fan outlets may need to be filled with bricks or concrete blocks and sealed from both the inside and outside.
Cracks in walls
You can fill in cracks using cements or hard-setting fillers, but if it’s a large crack there may be something wrong with your wall. Consult a surveyor or builder to see what caused the crack in the first place.
Air needs to flow in and out of your house so it stays fresh, dry and healthy. Make sure you don’t block or seal any intentional ventilation, such as the following:
- Extractor fans – take out damp air quickly in rooms where lots of moisture is produced (kitchens, bathrooms and utility rooms).
- Under-floor grilles or airbricks – help keep wooden beams and floors dry.
- Wall vents – let small amounts of fresh air into rooms.
- Trickle vents – modern windows often have small vents above them to let fresh air trickle in.