Draught-proofing your front door properly can save more on your heating bill than almost any other single weekend job in your home. The Energy Saving Trust estimates a typical semi-detached home saves around £85 a year just by sealing draughts around windows and doors, with further savings available from an unused chimney. This isn’t a renovation. It’s an afternoon with some foam strips and a letterbox brush.
If you read our guide on how to keep your house warm without turning the heating on, this is the deeper dive on the one section we kept brief there.
Most of the cold air getting into a UK home arrives through a handful of specific gaps: around the front door, around window frames, and down an unused chimney. Sealing those properly saves a typical semi-detached home around £85 a year, according to the Energy Saving Trust.
Start with the front door. It is usually the single biggest source, and it is an afternoon of work rather than a renovation.
Seal the gaps that lead outside. Leave the airflow inside the house alone.
Find the draughts first
Before buying anything, work out where the cold air is actually coming from. On a cold or windy day, these are the three signs worth checking for.
- What you noticeAir moving against your hand near a frameWhat it usually meansA gap where the opening section meets the frameStart hereFoam or brush strip along that frame
- What you noticeDaylight visible around a door or window frameWhat it usually meansA gap wide enough to sealStart hereMeasure the gap, then fit a strip to match
- What you noticeWhistling or rattling on a windy dayWhat it usually meansAir being forced through a narrow gapStart hereFollow the noise to its source and seal that point
Doors: the biggest single win in most homes
A front door is typically the largest single source of draughts in a UK home, and fixing it properly addresses four separate gaps.
Doing all four on your front door in a single weekend is worth prioritising over smaller fixes elsewhere in the house.
Cover the keyhole
A simple purpose-made cover that drops a small metal disc over the keyhole blocks this gap almost entirely, and it is one of the cheapest fixes available.
Seal the letterbox
A letterbox brush or flap seals this gap while still letting post through. Measure your letterbox before buying, since sizes vary considerably between doors.
Close the gap at the bottom
A brush strip or a hinged flap draught excluder fitted along the bottom of the door deals with the gap most people can actually feel with their hand on a cold day.
Two genuinely different approaches are worth knowing about here, since one is fitted and one simply sits in place. Both are covered directly below.
Seal around the edges
Foam, brush, or wiper strips fitted around the frame where the door meets it seal the remaining perimeter gap. This is the same principle as weatherstripping a window, just applied to a door.
Two ways to close the gap at the bottom
The Marwood Under Door Draught Excluder is a weighted, movable option that needs no fitting at all, just placed against the gap. At 4.6 stars from 5,200 reviews, owners consistently describe it as well-made and effective, with the weighted design specifically praised for staying put rather than sliding away from the door.
This is the better choice if you’re renting, don’t want to stick anything to the door, or want something you can move between rooms.
The Vellure Premium Door Draft Excluder Strip is the fitted alternative, sticking directly to the bottom of the door for a more permanent, integrated look, with one owner specifically describing it as sitting flush enough to look like part of the door itself.
At 4.4 stars from 23,700 reviews, it’s effective and easy to install, but there’s a genuine issue worth stating plainly: while many owners report it staying firmly in place, a meaningful number report the adhesive strip falling off shortly after fitting.
Windows
Self-adhesive foam strips are the cheapest, simplest starting point. They stick directly to the window frame and work well on casement windows, where the opening section presses against the frame when closed. Clean the surface first, measure and cut the strip to length, and press it firmly into place.
Brush or wiper strips work in a similar way and tend to suit windows with a sliding rather than a hinged action, since they allow the window to still move smoothly while sealing the gap.
Window insulation film is worth considering for an older or single-glazed window that’s a genuine cold spot. A clear film is taped around the frame, then shrunk tight with a hairdryer to remove wrinkles, creating an extra insulating layer of trapped air between the film and the glass.
It’s a temporary, removable fix rather than a permanent one, but it’s inexpensive and can make a real difference to a specific problem window over a single winter.
The chimney, if you don’t use it
An open, unused chimney can be one of the single biggest sources of heat loss in an older property, and a chimney balloon or a specific chimney draught excluder is designed to block this gap while remaining easy to remove if you ever want to use the fireplace again.
The one thing most guides get wrong: don’t over-seal your home
This is worth stating plainly, since it runs against the instinct to seal every gap in the house. Internal doors, between rooms inside your home, should be left with a small gap underneath rather than sealed. This gap allows air to circulate between rooms, which matters for ventilation and for allowing extractor fans in bathrooms and kitchens to actually work properly by drawing in replacement air from elsewhere in the house.
Draught-proofing is for gaps that let outside air in or heated air escape to the outside, not gaps between two rooms you’re already heating. This is exactly the nuance behind the internal-door note earlier in this guide: a weighted stopper on one regularly used room is a reasonable trade-off, but sealing every internal door in the house removes the airflow the whole system depends on.
The same principle applies at a whole-house level too. Draught-proofing genuinely works, with research suggesting it can reduce air leakage from windows by 33-50%, which meaningfully cuts how hard your heating has to work. But a home that’s sealed too aggressively, with every gap blocked and no ventilation left anywhere, traps the moisture produced by everyday living, cooking, showering, and breathing, which is exactly the condition that leads to condensation and mould.
The safest approach is to seal genuine draughts around external doors, windows, letterboxes, and unused chimneys specifically, while keeping basic ventilation in place, trickle vents left open, extractor fans in regular use, and a window cracked briefly each day in rooms prone to damp. If condensation or mould is already a concern in your home, it’s worth reading our guide to why your house might be so damp in winter alongside any draught-proofing work, since getting this balance wrong can make an existing damp problem worse rather than better.
The quick checklist
The whole guide, in the order worth doing it.
- Find the draughts first: hand test around frames, look for daylight gaps, listen for whistling
- Fix your front door first: keyhole, letterbox, bottom gap, and edges
- Fit foam or brush strips to windows, or use insulation film on a genuinely cold one
- Block an unused chimney with a balloon or excluder, never a chimney still in use
- Be careful with internal doors, they need some airflow to work properly
- Keep some ventilation everywhere else so you don't trade draughts for damp
Draught proofing: your questions answered
The Energy Saving Trust estimates a typical semi-detached UK home can save around £85 a year by sealing draughts around windows and doors, with further savings available from sealing an unused chimney. Research also suggests draught-proofing can reduce air leakage from windows by 33 to 50%, which meaningfully reduces how hard your heating system needs to work to maintain the same temperature.
The general advice is no, since internal doors need a small gap underneath for airflow and ventilation between rooms. In practice, many people do use a weighted draft stopper on a single, regularly used internal door to keep heat zoned in one room, and this is a reasonable compromise as long as other internal doors and general ventilation are left alone. Sealing every internal door in the house this way is where it becomes a genuine risk for trapped moisture.
Start with the front door, since it’s typically the single largest source of draughts in a UK home. Addressing the keyhole, letterbox, the gap at the bottom, and the gaps around the edges in one go usually has a bigger impact than several smaller fixes spread around the house. Windows and any unused chimney are the next priority after the front door is properly sealed.
Only if the chimney is genuinely unused. A chimney balloon or dedicated chimney draught excluder can block a significant source of heat loss in an unused fireplace, and is designed to be removable if you want to use the fireplace again later. Never block a chimney or flue that’s still connected to a working gas fire, wood burner, or open fire, since this creates a genuine carbon monoxide risk.
It can, if done without keeping any ventilation in place. Sealing every gap in a home traps the moisture produced by cooking, showering, and breathing, which is exactly the condition that leads to condensation and mould. The safer approach is to seal genuine draughts around external doors, windows, and unused chimneys specifically, while keeping trickle vents open, extractor fans in use, and occasionally airing rooms that are prone to damp.
Self-adhesive foam strips are the cheapest and simplest option, sticking directly to the window frame to block gaps on a casement window. Brush or wiper strips suit sliding windows better, since they allow smooth movement while still sealing the gap. Both are inexpensive, widely available, and can typically be fitted in under half an hour per window.
