Draught Proofing Your Home: Doors, Letterboxes, Chimneys and More

Draught proofing your home UK-wide is one of the cheapest and most effective energy efficiency measures available, yet it is consistently overlooked in favour of more glamorous upgrades. Sealing the gaps around doors, letterboxes, chimneys and other common draught sources can save between GBP 85 and GBP 145 per year on heating bills, with most DIY fixes costing under GBP 20 per item. This guide identifies every common draught source in a typical UK home, explains the best sealing methods for each, and helps you prioritise the quick wins that deliver the fastest payback.

Where to Draught-Proof Your Home

• External doors — fit self-adhesive foam or rubber draught strip around the frame and a brush strip along the bottom edge
• Letterboxes — add a letterbox draught excluder or brush plate cover to block cold air flowing through the flap
• Chimneys — use a chimney balloon, chimney sheep or cap to stop warm air escaping up unused flues
• Sash and casement windows — apply brush pile strips to sliding sashes or foam tape to casement edges
• Floorboard gaps — fill gaps between boards with flexible filler or use rugs to reduce draughts from below
• Loft hatches — add self-adhesive draught strip around the frame and insulation board to the hatch panel
• Pipework and cable holes — seal around pipes and cables entering the house with expanding foam or silicone

Draught proofing is one of the cheapest ways to improve your home’s energy efficiency, costing £100 to £300 for a professional to do the entire house or under £50 if you tackle it yourself. The Energy Saving Trust estimates draught proofing saves £45 to £125 per year on heating bills. Unlike insulation, it can be done with no disruption and requires no specialist tools.

Why Draught Proofing Matters for Energy Efficiency

Uncontrolled air leakage through gaps and cracks in the building fabric can account for 15-25% of total heat loss in a typical UK home. Every cubic metre of warm air that escapes through a draught is replaced by cold outdoor air that your heating system must then warm up, wasting energy and money.

The Energy Saving Trust estimates that draught proofing a typical semi-detached house saves approximately GBP 125 per year at current energy prices. For a detached house with more external surfaces and therefore more potential draught paths, savings can reach GBP 145 per year.

Critically, draught proofing does not mean sealing your home completely. Controlled ventilation through trickle vents, extractor fans and (in some homes) mechanical ventilation systems must be maintained to prevent moisture build-up and maintain healthy indoor air quality. The goal is to eliminate uncontrolled, unintentional air leakage while keeping intentional ventilation paths open.

Draught Proofing External Doors

External doors are the single biggest source of draughts in most UK homes. Gaps around the door edges, beneath the door and around the frame all allow cold air to stream in and warm air to escape.

Door Edge Seals

Self-adhesive foam tape or rubber strip seals applied around the door frame close the gap between the door edge and the frame. These are available from any DIY store for GBP 3-8 per roll and can be fitted in 15-20 minutes per door.

• Foam strip: Cheapest option (GBP 2-4), compresses when the door closes to fill the gap. Needs replacing every 2-3 years as the foam compresses permanently.
• Rubber strip (P-profile or E-profile): More durable than foam (GBP 4-8), maintains its shape longer, typically lasting 5-8 years.
• Brush strip: Fine nylon brushes in an aluminium or plastic carrier. Durable and effective for uneven gaps, costing GBP 5-10. Commonly used for sliding doors.

Door Bottom Seals

The gap beneath an external door is often the worst single draught source in the house. Solutions include:

• Brush strip door sweep: A strip of bristles in an aluminium holder, screwed to the bottom of the door. Cost: GBP 5-12. Effective, durable and works on uneven thresholds.
• Drop-down seal (automatic door bottom): A spring-loaded seal that drops down when the door closes and retracts when it opens, avoiding dragging on carpet. Cost: GBP 15-30. Best for interior doors opening onto unheated areas.
• Threshold seal: A rubber or aluminium strip fixed to the threshold that the door compresses against when closed. Cost: GBP 8-20. Combined with a door sweep provides a near-complete seal.

Letterbox Draught Proofing

A standard letterbox opening is approximately 250mm x 40mm, creating a rectangular hole in your front door that connects the heated hallway directly to the outside. The hinged flap provides minimal draught protection, particularly in windy conditions.

Effective letterbox draught-proofing solutions include:

• Internal letterbox brush cover: A brush-lined cover that fits over the inside of the letterbox opening. The brushes part to allow post through but close to seal the gap at all other times. Cost: GBP 5-15. The most popular and effective solution.
• Letterbox draught excluder flap: A secondary hinged flap on the inside of the door, providing a double-flap seal. Cost: GBP 8-20.
• External post box: For the most effective seal, consider a wall-mounted external post box that eliminates the need for a letterbox in the door entirely. Cost: GBP 20-50 plus fitting. The door can then be sealed completely.

Letterbox draught-proofing is one of the quickest wins. A brush cover takes less than five minutes to fit and immediately eliminates the cold draught that many hallways suffer from.

Chimney Draught Proofing

An open chimney flue is effectively an open window, allowing warm room air to rise up the chimney and escape while pulling cold air in through every other gap in the room to replace it. An unused chimney can waste GBP 50-100 per year in heating costs.

• Chimney balloon: An inflatable plastic balloon pushed up into the chimney flue and inflated to create an airtight seal. Cost: GBP 8-15. Must be removed before lighting a fire. Available in different sizes to fit various flue dimensions.
• Chimney sheep: A thick felt plug with a handle, pushed up into the flue opening. More durable than plastic balloons and easier to remove regularly if you use the fireplace occasionally. Cost: GBP 15-30.
• Chimney cap (external): A terracotta or metal cap fitted to the chimney pot on the roof. Provides permanent draught-proofing while still allowing some ventilation to prevent damp in the flue. Cost: GBP 30-60 for the cap, plus fitting costs if scaffolding or roof access is needed.
• Register plate: A metal plate sealed across the bottom of the chimney flue, above the fireplace opening. Provides a more robust seal than a balloon and is suitable for fireplaces that are never used. Cost: GBP 50-100 professionally fitted.

Important: if you block a chimney flue, you must maintain some ventilation to prevent damp and condensation inside the flue. An airbrick or small ventilation grille in the chimney breast or register plate prevents moisture problems in the unused flue.

Keyhole Covers, Cat Flaps and Other Door Draughts

Several other common door features create draught paths that are easy and cheap to address:

• Keyhole covers: A pivoting metal disc that covers the keyhole when the key is not inserted. Cost: GBP 2-5. A small detail that makes a noticeable difference in exposed hallways.
• Cat flaps: Standard cat flaps are extremely draughty. Microchip-activated cat flaps with magnetic seals provide much better draught resistance while still allowing your cat in and out. Cost: GBP 25-80.
• Door frame gaps: Gaps between the door frame and the wall are common, particularly in older properties where the frame has shrunk or the plaster has cracked. Fill with flexible decorators’ caulk (GBP 3-5 per tube) rather than rigid filler, which will crack as the materials move.

Skirting Board Gaps and Floor Draughts

In older UK homes with suspended timber floors, cold air from the subfloor void can enter the room through gaps between the skirting board and the floor, gaps between floorboards and around pipe penetrations.

• Skirting board gaps: Seal the gap between skirting and floor with flexible decorators’ caulk or silicone sealant. Cost: GBP 3-5 per room. Apply a bead of sealant along the joint and smooth with a wet finger.
• Floorboard gaps: Fill narrow gaps between floorboards with flexible wood filler or paper mache (papier mache made from newspaper and PVA glue is a traditional and effective method). Wider gaps can be filled with thin strips of timber tapped into place. Cost: GBP 5-15 per room for materials.
• Pipe penetrations: Where pipes pass through floors, fill the gap around the pipe with expanding foam (for hidden areas) or flexible sealant (for visible areas). Cost: GBP 5-8 per can of foam.

For a more comprehensive solution to floor draughts, consider full suspended timber floor insulation, which eliminates cold air movement beneath the floor entirely.

Unused Extractor Fans, Vents and Other Openings

Several other common features create unnecessary draught paths that are often forgotten:

• Extractor fan openings: Kitchen and bathroom extractor fans that are not in use allow cold air to flow back into the room through the duct. Fit a backdraught shutter (GBP 5-10) inside the duct that closes when the fan is off.
• Tumble dryer vents: The external vent for a tumble dryer can be a significant draught source when the dryer is not running. Fit a vent cover with a gravity flap (GBP 5-12) that opens only when the dryer is blowing.
• Loft hatches: An un-sealed loft hatch allows warm air to rise through the gap into the cold loft space. Fit self-adhesive foam tape around the hatch frame and consider adding a latch to compress the seal. See our detailed guide on loft hatch insulation.
• Pipe boxing: Boxed-in pipes that pass through external walls often have gaps at the top and bottom that connect to the wall cavity. Seal these with flexible filler or expanding foam.

Draught Proofing Windows

If your windows are older and you are not ready to replace them with new double glazing, draught-proofing the existing windows can significantly reduce air leakage:

• Casement windows: Apply self-adhesive rubber strip (P-profile or V-strip) around the frame where the opening casement meets the fixed frame. Cost: GBP 3-8 per window.
• Sash windows: Professional sash window draught-proofing using brush pile strips routed into the frame costs GBP 150-300 per window but dramatically reduces air leakage while allowing the sash to slide freely. DIY options include foam strip in the gap between the sashes and brush strip on the meeting rail.
• Secondary glazing: While not strictly draught-proofing, secondary glazing panels (from GBP 30 per window for DIY magnetic film systems up to GBP 200+ for sliding panel systems) create an additional sealed air layer that eliminates draughts and improves thermal performance.

Complete Draught Proofing Cost Summary

Here is what a comprehensive draught-proofing project costs for a typical three-bedroom semi-detached house, assuming DIY installation of most items:

With annual savings of GBP 85-145, the payback period for a comprehensive draught-proofing project is typically under two years, making it one of the fastest-payback energy improvements available.

Draught proofing pairs perfectly with insulation upgrades and heating improvements. Get a free quote to see what combination of measures delivers the best savings for your home.

Frequently Asked Questions

Should I draught-proof rooms with gas appliances?

Rooms containing open-flued gas appliances (such as gas fires, back boilers or older gas boilers) require adequate ventilation for safe combustion. Do not seal the permanent ventilation grilles in these rooms, as doing so creates a risk of carbon monoxide poisoning. If in doubt, have a Gas Safe registered engineer assess the ventilation requirements before draught-proofing. Room-sealed (balanced flue) boilers do not rely on room ventilation and can be draught-proofed normally.

Is professional draught proofing worth the cost?

Most draught-proofing tasks are straightforward DIY jobs. The main exception is sash window draught-proofing, where professional installation using routed-in brush pile strips is significantly more effective and durable than DIY alternatives. Professional sash window draught-proofing typically costs GBP 150-300 per window and is well worth the investment if you plan to keep your existing sash windows rather than replacing them.

Can draught proofing cause condensation?

Yes, if you seal all air leakage paths without providing replacement ventilation. The controlled air leakage through draughts does serve a ventilation function, even though it wastes energy. When you eliminate draughts, ensure your home has adequate trickle vents in windows, working extractor fans in bathrooms and kitchens, and clear airbricks for any rooms with subfloor voids. If condensation increases after draught-proofing, increase your background ventilation rather than reopening the draughts.

Are there grants for draught proofing?

Draught-proofing is an eligible measure under the ECO4 scheme for households on qualifying benefits. However, because the cost is relatively low, many households find it more practical to do the work themselves rather than navigating the grant application process. If you are having other insulation work done under ECO4, ask the installer whether draught-proofing can be included in the scope of the funded work.