Quick answer: Fit self-adhesive weather stripping around the edges of the door frame, add a brush strip or hinged flap draught excluder to the bottom, and cover the keyhole and letterbox with purpose-made covers. Test with a lit candle or incense stick held near the frame; if the flame flickers, there is still a draught to seal. Only draught proof external doors, since internal doors need a gap underneath for ventilation.
Draughts around doors are one of the most common and cheapest sources of heat loss in a UK home. Sealing them up is a straightforward weekend job that can noticeably improve comfort and, according to the Energy Saving Trust, save an average gas-heated semi-detached home around £60 a year.
Finding the Draughts
Before buying any materials, work out exactly where the cold air is getting in.
- Close the door fully and check for daylight visible around the edges, top, and bottom.
- Run your hand slowly around the frame on a windy day to feel for moving air.
- Hold a lit candle or incense stick close to the edges and watch for the flame flickering or the smoke bending, which pinpoints the exact gap.
- Check the keyhole and letterbox specifically, since these are common but often overlooked draught sources.
What You Will Need
- Self-adhesive weather stripping (foam, rubber, or brush type)
- A brush strip or hinged flap draught excluder for the bottom of the door
- A keyhole cover
- A letterbox flap or brush, measured to fit your letterbox
- A tape measure, scissors or a hacksaw, and a screwdriver
Choosing the Right Material
Different draught excluder materials suit different situations.
- Rubber strips are durable and work well for external doors exposed to weather.
- Brush strips are flexible and cope well with slightly uneven surfaces or worn frames.
- Foam strips are the cheapest and easiest to fit, though they tend to compress and wear out faster than rubber or brush types.
- Silicone seals hold up well for heavy, frequent use, making them a solid choice for a busy front door.
Step 1: Seal the Edges and Top of the Door
- Clean the door frame thoroughly so the adhesive strip bonds properly. Grease or dust will stop it sticking long term.
- Measure the top and both sides of the frame carefully.
- Cut the weather strip to length using scissors or a hacksaw, depending on the material.
- Peel back the adhesive backing and press the strip firmly into place along the frame, working in one continuous motion to avoid air bubbles or gaps.
- Close the door to check the fit. It should seal snugly without making the door difficult to open or close.
Step 2: Fit a Draught Excluder to the Bottom
The bottom of the door is usually the largest single gap and the easiest source of draughts to fix.
- Measure the width of the door with it closed.
- Cut a brush strip to length, then screw it to the bottom edge of the door, checking that the bristles reach the floor to form a proper seal.
- Alternatively, fit a hinged flap draught excluder, which lifts automatically as the door opens and drops back down when closed.
Step 3: Cover the Keyhole
Fit a purpose-made keyhole cover, which typically has a small metal disc that drops down to close the hole when the key is not in use.
Step 4: Cover the Letterbox
- Measure your letterbox opening before buying a replacement flap or brush, since sizes vary considerably between doors.
- Fit a letterbox brush or flap, or consider a wall-mounted external letterbox if you want to avoid a hole in the door altogether.
Sealing Gaps Around the Frame Itself
If you have checked all the visible seals and still feel a draught, the gap may be between the frame and the surrounding wall rather than the door itself. Building caulk, expanding foam, or silicone sealant can close these gaps, though foam should be used sparingly since it expands over time and can distort the frame if overapplied.
Why Internal Doors Should Not Be Draught Proofed
It is worth knowing that draught proofing advice applies to external doors, not internal ones. Internal doors should keep a small gap underneath to allow air to circulate properly through the home. Sealing internal doors too tightly can restrict airflow needed for ventilation and, in some cases, can affect how appliances like gas boilers draw air safely. Focus your draught proofing efforts on doors leading directly outside, and any doors separating a heated room from an unheated one, such as an unused spare room.
Don’t Forget the Chimney
If you have a fireplace you rarely or never use, an open chimney can be a significant source of draughts elsewhere in the home. Fitting a cap over the chimney pot, usually made from terracotta, blocks draughts while still protecting against moisture and birds.
How Much Can Draught Proofing Save?
According to the Energy Saving Trust, draught proofing doors and windows can save the average gas-heated semi-detached home in England, Scotland, or Wales around £60 a year, since less heat is lost and you can typically turn your heating down slightly without losing comfort.
Related Guides
Frequently Asked Questions
How do I know if my door needs draught proofing?
Check for visible daylight around the frame, feel for moving air with your hand on a windy day, or use the candle or incense test to spot exactly where air is getting through.
Should internal doors be draught proofed?
No. Internal doors should keep a gap underneath for ventilation. Draught proofing is intended for external doors and doors separating heated rooms from unheated ones.
How much can draught proofing a door save on energy bills?
Around £60 a year for an average gas-heated semi-detached UK home, according to the Energy Saving Trust, when combined with draught proofing windows too.
What is the best material for a door draught excluder?
Rubber strips suit external doors exposed to weather, brush strips work well on uneven or worn frames, and silicone seals hold up best for doors used frequently throughout the day.
Final Thoughts
Draught proofing a door is one of the cheapest, quickest home improvements you can make, usually finishable in an afternoon with materials costing well under £30. Focus on external doors, cover the keyhole and letterbox, and leave internal doors with their ventilation gap intact for a warmer, more comfortable home without compromising air quality.