How to Stop Draughty Windows and Keep Heat In

A cold line of air around the edge of a window can make an otherwise warm room feel uncomfortable, particularly on a windy winter evening. If you are wondering how to stop draughty windows, the right answer depends on where the air is coming from. A worn seal may need a straightforward repair, while an older window that has warped, dropped or lost its insulating performance may be better replaced.

The key is to identify the cause before buying temporary draught-proofing products. That helps you spend money where it will make a genuine difference to comfort, heating costs and the long-term condition of your home.

Find where the draught is coming from

Start on a cool or windy day, when the problem is easiest to notice. Slowly run the back of your hand around the frame, opening section and internal window board. You may feel air at the sides of the sash, through the joint between the frame and wall, or from a particular opening corner.

A thin piece of tissue can also help. Hold it near suspected gaps and watch for movement, but keep it away from candles or any other naked flame. Look carefully for visible cracks in sealant, flattened rubber gaskets, gaps in timber joints and frames that do not close evenly.

It is worth separating a true draught from cold glass. Single glazing, old double glazing and poorly insulated frames can feel very cold without allowing outside air into the room. This still affects comfort, but it calls for better glazing rather than simply sealing a gap.

Also check whether the air is deliberately entering through a trickle vent. These vents support background ventilation and can help manage condensation and indoor air quality. Do not permanently block them without professional advice. If a vent feels excessively cold or cannot be adjusted properly, it may need inspecting rather than covering over.

How to stop draughty windows with simple repairs

Once you have found the source, a few modest repairs can often improve a window that is otherwise in good condition. These are most effective when the frame is sound, the glass units are clear and the window opens and locks correctly.

Replace worn weather seals

Most modern uPVC and PVCu windows use rubber or foam gaskets around the opening sash. Over time, these can become compressed, brittle or detached, leaving a channel for air to pass through. If the gasket looks cracked, loose or permanently flattened, replacing it with the correct profile can restore a tighter seal.

The profile matters. A seal that is too thick can make the handle difficult to operate, while one that is too thin will not close the gap. For this reason, matching the replacement gasket to the existing window system is usually safer than choosing a generic roll of draught excluder.

For older timber windows, self-adhesive foam, rubber or brush strips can be a useful short-term measure. Clean and dry the surface first, then apply the strip without stretching it. Foam strips are inexpensive and easy to fit, but they tend to wear more quickly than quality rubber seals and may prevent a tight closure if over-applied.

Repair gaps around the frame

A draught may be passing between the window frame and the surrounding wall, not through the opening itself. Internally, look for failed or cracked sealant around the reveal, particularly at the top corners and beneath the window board. Small gaps can normally be resealed with a suitable interior decorator's caulk or sealant.

Outside, failed perimeter sealant can allow wind-driven rain as well as cold air to reach the edges of the installation. External repairs need the right product, a clean surface and dry conditions. If the gap is large, the frame is moving or there are signs of damp, it is better to have the installation assessed. Simply filling a substantial void may hide a more significant problem.

Check hinges, handles and alignment

Casement windows can become draughty when the sash has dropped slightly or the hinges have worn. You may notice that the handle is harder to lock, there is an uneven gap around the sash, or one corner is visibly not pulling against the seal.

Some uPVC window systems allow minor hinge or locking adjustments, but these should be carried out carefully. Over-adjustment can strain the hardware, worsen the fit or affect how securely the window locks. A competent window technician can inspect the hinges, keeps and locking points, then make the small adjustments needed for an even, secure closure.

Do not ignore a window that needs force to shut. That is rarely just an inconvenience. It can be an early sign that hardware, hinges or the frame itself needs attention.

Temporary measures for a colder room

Temporary draught reduction can be worthwhile while arranging a repair or planning replacement windows. Heavy, close-fitting curtains can reduce the sensation of cold near the glass, especially overnight. Thermal blinds may also help, provided they do not interfere with the window opening or restrict essential ventilation.

Secondary glazing film can add a still layer of air inside single-glazed windows during the heating season. It is a practical, low-cost option for some properties, but it is not a substitute for repairing failed frames or upgrading inefficient glazing. Poorly fitted film can look untidy and may be inconvenient if the window needs to be opened regularly.

For a clearly defined gap at the bottom of an older sash window, a purpose-made draught strip may make a noticeable difference. Avoid stuffing towels, tape or expanding foam into drainage holes, trickle vents or opening mechanisms. Windows need to shed water correctly and, where designed to do so, provide controlled airflow.

When a repair is no longer the best value

Repairs make sense when they solve a specific fault. They become less convincing when draughts are one symptom of an ageing window with several problems. Misted panes, internal condensation between glass layers, discoloured frames, recurring leaks, difficult locks and noticeable outside noise often point to a system nearing the end of its useful life.

Failed double-glazed units are a common issue. When the perimeter seal around the glass breaks down, moisture enters the cavity between the panes. The result is misting or droplets inside the unit, along with reduced insulation. Replacing the sealed glass unit may be possible if the frame and hardware remain sound. However, if the frames are warped, the seals are failing throughout and locks are unreliable, full replacement can offer better value and a more dependable result.

Modern made-to-measure uPVC windows can improve airtightness, thermal performance and security at the same time. The benefit does not come from the frame alone. Accurate surveying, appropriate glass specification, careful installation and tidy sealing around the opening all matter. A well-made window can still underperform if it is poorly fitted.

For homes in SW London and Surrey, this is particularly relevant where properties range from older, characterful houses to later extensions with mismatched glazing. The most suitable replacement is not always the same from room to room. A north-facing bedroom, a busy-road living room and a warm south-facing kitchen may have different priorities for insulation, noise reduction, privacy and solar control.

Avoid common draught-proofing mistakes

The quickest fix is not always the best one. Sealing every opening indiscriminately can reduce ventilation and make condensation worse, especially in kitchens, bathrooms and bedrooms. Condensation is caused by moisture in the air meeting a cold surface, so the solution may involve improving ventilation, heating patterns and insulation rather than closing every vent.

Be cautious with expanding foam around window frames. It has limited use in the right hands, but it can distort frames, obstruct drainage paths and create a difficult repair later. Likewise, surface sealant will not correct a window that is badly out of square or a double-glazed unit that has failed internally.

It also pays to consider access and safety. Upper-floor windows, large panes and stiff or damaged hinges are not sensible DIY jobs. A professional inspection can establish whether a targeted repair is realistic and explain the likely lifespan of that repair before you commit.

A practical route to a warmer home

Begin with the easy checks: identify the exact gap, inspect seals and closing action, and repair small defects before they become larger ones. If the windows are otherwise healthy, new gaskets, sealant or a hardware adjustment may be all that is needed.

Where draughts come with misted glass, failed locks, persistent cold spots or ageing frames, a tailored replacement survey gives you clearer answers than another temporary fix. Filus can assess the condition of your existing windows and specify a made-to-measure option that suits your home, rather than treating every draught as the same problem.

A warmer room should not rely on turning the thermostat higher. Address the source of the draught, keep ventilation working as intended, and you can make your home feel more comfortable through every cold spell.