Draught-Proofing Doors and Windows

Draught-proofing seals the unintended gaps around doors and windows that let cold air in and warm air out, without sealing the deliberate ventilation routes a home still needs. It is usually the cheapest fabric measure available, and it often improves comfort more than its cost suggests, because a draught felt on the neck at a desk or sofa makes a whole room feel cold even when the air temperature is reasonable. The work is small in scale but fiddly in detail, because every opening type needs a different seal.

Compression seals suit casement windows and doors that close against a frame, brush strips suit sliding sash windows and the bottom of doors, and foam strips are a short-life option best reserved for temporary or rarely opened gaps. Letterboxes, keyholes, cat flaps and service penetrations around doors are separate draught routes that are often missed when only the door edge is sealed.

In practice, draught-proofing starts by finding the gaps, not by buying seals in bulk. A hand held near the edge on a windy day, a thin paper strip closed in the sash, or a smoke pencil used carefully will show where air actually moves, and the pattern often surprises: a sash window may leak at the meeting rail rather than the sides, and a door may leak at the threshold rather than the jambs. Seals should be fitted to the gap size and the closing action, so the window or door still closes, locks and, where relevant, provides a fire escape route without force.

For sash windows, specialist draught-proofing involves fitting seals into grooves in the sash and staff beads, which preserves the window appearance and operation, while casement windows can take adhesive or groove-in compression seals. Doors need a threshold seal that does not trip users or block wheelchair access, and any seal that interferes with a fire door closer or intumescent strip must be checked by a competent person.

Check each opening for gap size, closing action, lock function and whether it is a fire escape or fire door, and note any existing vents or fans that provide background ventilation. Photograph the gap pattern before work, and test every window and door after sealing to confirm it still opens, closes and locks easily.

Also check combustion appliances: a home with an open fire, a solid-fuel stove or a gas appliance that relies on room air needs a permanent ventilation opening that draught-proofing must not block. If you are unsure, ask a qualified professional before sealing a room that contains such an appliance.

In the EU, draught-proofing and airtightness are addressed through national building regulations and renovation guidance under the EPBD framework, with member states differing on airtightness testing, ventilation requirements after sealing and product standards for seals. A measure that is routine in one country may need a ventilation upgrade in another, depending on the local regulatory baseline.

In the UK, Approved Document F sets ventilation expectations that interact directly with draught-proofing, and Approved Document L covers airtightness in new and renovated work. Devolved building standards add local detail, and fire safety rules govern seals on fire doors, so the local documents for the property should be checked together.

A frequent mistake is sealing every gap including trickle vents, then wondering why condensation and cooking smells worsen, when the home has lost its background ventilation. Another is fitting a seal that is too thick, so the window or door is forced shut, the lock strains and the seal compresses permanently within months, leaving a worse gap than before.

A third mistake is draught-proofing only the obvious front door while ignoring a back door, a loft hatch or a cellar door that leaks just as much. A whole-house draught survey, room by room, finds the routes that a single-door job misses.

Keep a note of the seal types fitted to each opening, the supplier and size, photographs before and after, and any ventilation advice given alongside the work. Those records help a later occupant replace a worn seal with the right type instead of guessing.

Ask a qualified installer: which seal suits each opening type here, what ventilation remains after sealing, are any fire doors or combustion appliances affected, and how long should each seal last. Opening-specific answers show careful draught-proofing.