How to stop draughts around windows and doors

Most draughts around double glazed windows and doors come from one of three places. The rubber seal in the frame has flattened, shrunk or pulled away, the window or door has dropped on its hinges so it no longer closes tight against that seal, or air is getting in through a gap that has nothing to do with the glass at all, such as a letterbox, a keyhole or the joint between the frame and the wall. Find which one it is before you spend anything, because the first two are usually a repair and the third is often a job you can do yourself.

What you should not do is seal everything you can find. Trickle vents, airbricks and extractor fans are there on purpose, and blocking them swaps a draught for condensation and damp. The rest of this guide covers how to find the draught, how to fix each kind, what to leave alone, and the point at which a draught really is telling you something needs replacing.

Find the draught before you fix anything

A draught is easier to find on a cold, windy day than to remember on a still one, so wait for the weather to help. The Energy Saving Trust's guide to draught proofing suggests the obvious clues first. Look for daylight around the edges of a door or an opening window, listen for whistling or rattling when the wind is up, and watch for curtains moving when the window behind them is shut.

Then go round with the back of your hand, slowly, along every edge of every opening sash and door. A draught at the corners of a sash usually points to the seal. A draught along the whole of the side away from the hinges usually points to a sash that is not being pulled in tight. A draught around the outside of the frame, where it meets the plaster, is a different problem again, and no amount of work on the window itself will cure it.

There is a simple test for the middle one. Close the window on a strip of paper and try to pull it out. If it slides out easily the sash is not compressing the seal at that point, and if it holds firmly the seal is doing its job. Do it at several points around the sash, because a window that has dropped will usually grip at one corner and not at the opposite one.

Seals that have flattened, shrunk or come away

Every modern window and door seals against a run of rubber gasket set into the frame and the sash. Over the years that gasket can harden, shrink back from the corners, flatten where it is compressed every day, or simply come out of its groove. When it does, air gets past it on every gust of wind, and the window can feel draughty even though the glass and the frame are perfectly sound.

A tired gasket is a replaceable part. Pulling the old one out and fitting a new run is a modest job, and it is one of the repairs we carry out. It is one of the clearest examples of a draught that sounds like a big problem and is not one.

It is also why stick on foam strip is rarely the answer on a uPVC window. The Energy Saving Trust points out that self adhesive foam is cheap but may not last long, and that a strip which is too thick gets crushed and can stop the window closing properly. A replacement gasket works better than foam strip on a modern window, because it sits in the groove the window was designed around and restores the seal the frame was made to close against, rather than adding a second one in the way of it.

Some of it is simply care. The homeowner's maintenance guide our supplier publishes, which is in our maintenance guides, recommends cleaning gaskets periodically with soapy water to preserve them, and cleaning more often in coastal areas. For a composite door it says that if any part of the perimeter weatherseal has come loose, it can simply be pushed back into position so the door closes on a tight, consistent seal. That is worth trying before anything else.

A window that no longer closes tight

The other common cause on a casement window is the sash itself. Hinges wear, and as they do the sash drops slightly, so it catches on the frame as it closes and no longer pulls evenly against its seal. Many uPVC windows also have adjustable locking cams along the edge of the sash, which set how hard the window is drawn in when the handle is turned, and over time those can end up set too loose.

Both are adjustments rather than replacements. Worn hinges can be changed, the sash can be reset in the frame, and the locking can be set so the window closes firmly without having to be forced. If the handle has become stiff, or the window needs lifting or pushing before it will lock, that is the same problem showing itself, and it is worth sorting before the locking mechanism wears out under the strain. A window that is hard work to close is very rarely a window that needs replacing.

Draughts around external doors

External doors take more punishment than any window. They are opened and closed far more often, they carry more weight on their hinges, and they have more ways for air to get round them. The letterbox, the keyhole, the threshold and the edges of the door itself are all candidates.

The Energy Saving Trust suggests a letterbox brush or flap, a keyhole cover and a brush or flap excluder along the bottom of the door, and all three are cheap and worth having. On a modern door the bigger draught is very often the door itself. A door that has dropped stops meeting its seals evenly. If you have to lift the handle hard or lean on the door before the key will turn, the locking points are not fully entering their keeps, which leaves the door only partly locked as well as only partly sealed.

The same supplier guide says to make sure all the locking points are fully engaged whenever a composite door is closed, because that keeps the door stable and properly aligned as the temperature changes. Locking it properly every time is part of keeping it sealed. Where it will not lock without a fight, that is a straightforward adjustment in most cases, on the hinges or the keeps. Door adjustments and servicing sit on the same repairs list as gaskets and hinges.

What you should never seal

Air has to move through a house to keep it dry and healthy, and some of the gaps you will find are there deliberately. The Energy Saving Trust is clear that you should not block extractor fans, airbricks or underfloor grilles, wall vents or trickle vents. Rooms with an open fire, a flue or a gas appliance need their ventilation for safety as well as comfort, and kitchens and bathrooms need it to deal with moisture. Internal doors should not be draught proofed at all, because the gap beneath them is part of how air moves around the house.

Trickle vents are the ones people are most tempted to tape over, because they sit in the head of the window and can feel like a draught in their own right. Leave them working. They are a controlled way of letting fresh air in, and in England a replacement window has to leave a home with at least the ventilation it had before, which in most homes means trickle vents, as Local Authority Building Control explains in its guide to replacement windows and trickle vents. A house sealed tight with every vent taped over is a house far more likely to see condensation and damp through the winter, which is a worse problem than the draught was.

Older timber windows are a different job

Everything above is about modern double glazing. Older timber casements and sliding sashes are draughty for different reasons, mainly because the timber has moved and the gaps around each sash have opened up over decades. The Energy Saving Trust notes that foam strips do not work well on sliding sash windows and that brush strips or professional help are the better route, and that older homes with traditional features often need specific materials and more care.

If the windows are original to an older house and you want to keep the look, it is worth reading about windows for older Lincolnshire homes before deciding whether to draught proof them or replace them with something like a sliding sash or a flush casement made to match.

Why the side of the house facing the weather goes first

On this coast the wind is stronger and more constant than it is a few miles inland, and it drives rain and fine sand at the elevation that faces it. That puts more pressure on every seal and every hinge on that side of the house, so it is the side where a tired seal is most likely to show itself first, while the same windows round the back can seem fine. Salt in the air also works on hinges and locking hardware over time, which is part of how a sash ends up dropping.

The practical point is to start your search on the side that takes the weather. How coastal weather affects windows goes further into what salt, wind and sand each do, and what keeping on top of them involves.

When a draught really does mean replacement

Sometimes the draught is the symptom of something bigger. A frame that has distorted so the sash can no longer be made to sit square, hardware that is no longer made for an old window system, a door that has warped rather than dropped, or old single glazing are all cases where adjustment will not get you a sound seal. That is also when the rest of the window is usually near the end of its life anyway, which how long double glazed windows last covers in more detail.

When it does come to that, the difference can be marked. Brent Jones said of the new front door we fitted that it is "far better insulated then my previous door". Our windows come A rated as standard, the doors range runs from PVCu to composite, and as a FENSA registered installer we register replacement windows and doors in your home and you get the certificate.

Getting a draught looked at

If you have found the draught and it is a seal, a dropped sash or a door that will not close properly, it is usually a repair. If you are not sure which it is, describe it to us and we will tell you honestly. You can get a free no-obligation quote or ring Piper Windows on 01754 898 998. We are happy to look at all repairs, whoever fitted the window or the door.