Draught-Proofing Your Home: One of the Cheapest Ways to Cut Heat Loss
The short answer
- About £250 for professional draught-proofing of windows and doors in a whole house, and less if you do it yourself
- About £55 a year saved on windows, doors and floors, plus about £45 a year for an unused open chimney
- About five years to pay back at the professional price. Seal the accidental gaps, never the vents
Draught-proofing is one of the cheapest energy improvements you can make. The Energy Saving Trust puts professional draught-proofing of windows and doors at about £250 for a whole house, with DIY cheaper, and estimates that draught-proofing windows, doors and floors saves about £55 a year in Great Britain. Blocking an open chimney you do not use could save about £45 a year more. Draught-free rooms also feel comfortable at a lower temperature, so you may be able to turn the thermostat down. The one thing to get right is ventilation: seal the accidental gaps, never the vents. This guide covers where draughts come from, how to fix each one, what it costs, and when to call a professional.
Where do draughts come from?
Mostly through suspended timber floors, windows, external doors and unused chimneys. Letterboxes, loft hatches, skirting gaps and pipe holes add more; older homes with sash windows and timber floors usually leak the most.
| Source | Typical fix | Difficulty |
|---|---|---|
| Suspended timber floors | Fill gaps between boards and seal along the skirting | Moderate |
| Windows (sash and casement) | Foam, rubber or brush strips around the opening parts | Easy (sash: moderate) |
| External doors | Strip around the frame, brush or blade excluder at the bottom | Easy |
| Chimneys and fireplaces | Removable chimney draught excluder, or a cap on the pot | Easy |
| Letterboxes and keyholes | Letterbox brush or flap, keyhole cover | Easy |
| Loft hatch | Draught strip around the frame, insulation on top | Easy |
| Pipe and cable penetrations | Filler or sealant around the gap | Easy |
| Skirting board gaps | Decorator's caulk or flexible filler | Easy |
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Draughts are uncontrolled air leaks through gaps in your home's structure. They are different from ventilation, which is controlled airflow needed for moisture removal and indoor air quality. The goal of draught-proofing is to seal the uncontrolled leaks while keeping intentional ventilation working.
Where your home leaks most depends on its age and condition. Older homes with sash windows and timber floors usually leak the most.
How do you draught-proof each area?
Seal the accidental gaps with strips, brushes, filler and excluders, and leave the vents alone. Use foam or rubber strip on casements, brush pile on sashes, flexible filler on floorboards and a removable excluder in an unused chimney.
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Windows
Casement windows (hinged): Apply self-adhesive foam or rubber strip around the frame where the window closes against it. Clean the surface first, cut to length, and press firmly into place. Foam strips are the cheapest but wear out soonest. Rubber strips (P-profile or E-profile) cost slightly more but last longer and seal more effectively.
Sash windows: The sliding channels are the main leak point. Brush pile strip (a strip of dense bristles in a carrier) fitted into a groove in the sash channel seals the gap while allowing the window to slide freely. This is the standard fix for sash windows. You can buy kits, or have a specialist fit it, which suits period homes with several sash windows.
Trickle vents: Do not seal trickle vents. They provide background ventilation that prevents condensation and maintains air quality. If you find your trickle vents are a significant draught source, they may be damaged and need replacing rather than blocking.
External doors
The gap between the door and frame is the primary leak. Fit self-adhesive strip around the door frame (same approach as casement windows). For the bottom of the door, fit a brush strip or rubber blade excluder that seals against the threshold when closed. A letterbox draught excluder (a hinged flap or brush cover) makes a noticeable difference, especially on front doors facing the prevailing wind, and a keyhole cover (a small rotating disc) closes the last gap.
Floors
Suspended timber floors (common in homes built before the 1950s) are one of the biggest draught sources. Air enters through gaps between floorboards, between the skirting and floor, and through ventilation grilles in the external wall beneath the floor.
Floorboard gaps: Fill with flexible filler, papier-mâché, or purpose-made floor gap filler strips. Do not use rigid filler as the boards move seasonally and will crack it out. For very wide gaps, consider having the floor sanded and the gaps filled by a floor specialist.
Skirting board gaps: Run a bead of decorator's caulk or another flexible filler along the junction between the skirting board and the floor, and between the skirting and the wall. This is one of the quickest, cheapest fixes with immediate impact.
Underfloor ventilation: Do not block air bricks or ventilation grilles in external walls below suspended timber floors. These prevent moisture buildup and rot in the floor timbers. The draught-proofing approach for floors is to seal gaps in the floor surface itself, not to block the underfloor ventilation.
Chimneys and fireplaces
If you do not use the fireplace, fit a removable chimney draught excluder, such as a chimney balloon that sits inside the flue. It should not block the chimney completely, so that some air still flows. Always remove it before lighting a fire. A cap on the chimney pot keeps out rain, birds and draughts; the Energy Saving Trust says caps start at around £150. It estimates that draught-proofing an unused open chimney could save about £45 a year.
If you have sealed off a fireplace but the chimney is still open at the top, consider having the chimney capped. A cowl or cap prevents rain entry and reduces downdraught. A ventilation grille in the fireplace or chimney breast prevents condensation in the unused flue.
Loft hatch
An uninsulated, unsealed loft hatch is a major heat leak. Fit a strip of self-adhesive foam or rubber around the hatch frame to seal the gap when closed. Add a slab of rigid insulation (50 to 75mm PIR board) to the top of the hatch door with adhesive. This is also covered in our DIY loft insulation guide.
Pipe and cable penetrations
Anywhere a pipe or cable passes through an external wall or ceiling creates a gap. Fill around these penetrations with expanding foam (for large gaps) or decorator's caulk (for small gaps). Common locations include around boiler flue pipes, where water pipes enter from outside, cable entry points, and extractor fan ducts.
Do not seal ventilation for gas appliances
Never block a vent, air brick or grille that serves a gas appliance, an open fire or a flue. Open-flued and flueless appliances, such as some gas fires and older boilers, need a permanent air supply to burn safely. Kitchens, bathrooms and rooms with open fires also need good ventilation. If in doubt, ask a Gas Safe registered engineer before draught-proofing a room with a gas appliance.
Should you do it yourself or hire a professional?
About £250 for a professional to do the windows and doors of a whole house, and less if you do it yourself. A chimney pot cap starts from around £150; sash windows and period features may need a professional.
| Approach | Cost (whole house) | Best for |
|---|---|---|
| DIY (strips, caulk, excluders) | Less than professional | Doors, casement windows, letterboxes, loft hatch, skirting, unused chimneys |
| Professional, windows and doors | About £250 | Sash windows, awkward frames, full-house treatment |
| Chimney pot cap | From around £150 | Chimneys you will not use again |
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The data behind this table
Source: Energy Saving Trust, Great Britain, updated 20 May 2026. Older homes with traditional features can be harder to draught-proof, and the Energy Saving Trust suggests professional help for those.
How much does draught-proofing save?
About £55 a year, paying back in about five years at the professional price and sooner if DIY. An unused open chimney saves about £45 more, and turning the thermostat down from 22°C to 21°C saves about £120.
| Measure | Annual saving | Payback |
|---|---|---|
| Draught-proofing windows, doors and floors | About £55 | About 5 years at £250; sooner if DIY |
| Draught-proofing an unused open chimney | About £45 | Depends on the method |
| Turning the thermostat down from 22°C to 21°C | About £120 | Free |
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The data behind this table
Source: Energy Saving Trust estimates for Great Britain, updated 20 May 2026. These are modelled estimates at the Energy Saving Trust's prices, not measured savings; the government has not published measured savings for draught-proofing. A home that is already fairly airtight saves less.
At about £250 against about £55 a year, professional draught-proofing pays back in about five years, and DIY sooner. Beyond the financial return, the comfort improvement is immediate: no more cold draughts across your feet, fewer cold spots near windows, and a more even temperature throughout the house. Use our insulation savings calculator to see how draught-proofing combines with other upgrades.
Should you draught-proof before a heat pump?
Yes, draught-proof first. A heat pump delivers warmth at lower temperatures, so draughts are more noticeable; with loft and cavity insulation, it cuts heat demand and can allow a smaller, cheaper heat pump.
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If you are planning a heat pump, draught-proofing is essential preparation. Heat pumps deliver warmth at lower temperatures than gas boilers, which means draughts are more noticeable. Cutting them reduces the heat pump's workload and your electricity bills.
Combined with loft insulation and cavity wall insulation, draught-proofing reduces your heat demand, which can allow a smaller, cheaper heat pump. Use our heat pump calculator to see the impact.
How do you keep a draught-proofed home ventilated?
Seal the gaps but keep the ventilation working. Keep trickle vents open, extractor fans working and air bricks clear; a home with no trickle vents, wall vents or mechanical ventilation may already be too airtight.
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A well draught-proofed home needs adequate ventilation to prevent condensation and maintain air quality. This is especially important after insulating, as a tighter building envelope traps more moisture indoors. The Energy Saving Trust warns that if your home has no trickle vents, wall vents or mechanical ventilation, it may already be too airtight for more draught-proofing, and a home that is already fairly well sealed risks poor air quality if you seal it further.
At a minimum, keep trickle vents on windows open, ensure extractor fans in kitchens and bathrooms work properly, and never block air bricks serving gas appliances or underfloor spaces. If you notice increased condensation on windows after draught-proofing, you may need to improve ventilation rather than reverse the draught-proofing.
For heavily insulated and draught-proofed homes, mechanical ventilation with heat recovery (MVHR) provides fresh air while recovering much of the heat that would otherwise be lost through open windows.
If condensation appears after draught-proofing, read our condensation and mould guide. Use our EPC improvement planner to see how draught-proofing affects your rating alongside other improvements.
Frequently asked questions
How much does draught-proofing cost?
The Energy Saving Trust puts professional draught-proofing of windows and doors at about £250 for a whole house. Doing it yourself with strips, brushes, a letterbox cover and caulk costs less. A cap for an unused chimney pot starts at around £150.
How much does draught-proofing save?
The Energy Saving Trust estimates about £55 a year in Great Britain for draught-proofing windows, doors and floors, and about £45 a year for an unused open chimney. Draught-free rooms also feel comfortable at a lower temperature, and on its estimates turning the thermostat down from 22°C to 21°C saves about £120 a year.
Where are the biggest draughts in a house?
Common sources are gaps in suspended timber floors and along skirting boards, windows and external doors, letterboxes and keyholes, unused chimneys, loft hatches, and holes where pipes and cables pass through walls. Where your home leaks most depends on its age and condition: older homes with sash windows and timber floors usually leak the most. Our EPC improvement guide covers the wider priority order.
Can you draught-proof sash windows?
Yes. Brush pile strips fitted into the sliding channels seal the gaps between the sashes and the frame while letting the windows slide. It is one of the most effective draught-proofing jobs in period homes, and a specialist can fit it if you would rather not.
Should I draught-proof my house if I have a gas boiler?
Yes, but never block a vent, air brick or grille that serves a gas appliance, open fire or flue. Open-flued and flueless appliances need a permanent air supply to burn safely. Most modern boilers are room sealed and take their air from outside, but if you are unsure, ask a Gas Safe registered engineer before sealing a room.
Data sources
Costs, savings and ventilation advice come from the Energy Saving Trust, with ventilation guidance from Building Regulations Approved Document F.
Show every source
Costs, savings and ventilation advice from the Energy Saving Trust (draught-proofing, updated 20 May 2026). Ventilation guidance from Building Regulations Approved Document F.