A leaking door can add hundreds of pounds to your heating bill
A leaking external door lets in cold air and rainwater, making your home harder to heat. According to the Energy Saving Trust, draught-proofing a home can save up to £125 per year on energy bills, and a poorly sealed external door is a major source of heat loss (Energy Saving Trust, 2026). Water ingress through a door is not just an inconvenience; it can lead to damp, rot, and structural damage, costing thousands in repairs. This article breaks down the specific costs, savings, and payback periods for the most common fixes.
Stopping water through a door costs £10–£450 depending on the fix. DIY weatherstripping or a door sweep pays back in under a year. A professional threshold or re-hanging costs more but stops damp and rot long-term.
- Replace worn weatherstripping for £10–£30, payback under 1 year.
- Fix a damaged door sweep for £15–£40, saving £40–£80 yearly.
- Replace a failed threshold professionally at £180–£450.
- Re-hang a sagging door for £100–£250, payback 2–5 years.
- Draught-proofing all gaps saves up to £125 per year total.
- A leaking door can add hundreds of pounds to your heating bill
- The three main causes of water entry through a door
- Quick numbers – cost, savings, and payback for each fix
- Replacing weatherstripping is the cheapest fix and pays back in under a year
- A new door sweep or threshold is the most effective solution for bottom-of-door leaks
- The direct answer to "stop water through door" – seal the gap at the bottom
- Professional door adjustment or replacement – when DIY won't work
- How to verify your installer and ensure the work is guaranteed
The three main causes of water entry through a door
Water usually enters through a door because one of three components has failed. First, worn or missing weatherstripping – the rubber or foam seal around the door frame degrades over time, creating gaps for water and air. Second, damaged or misaligned door sweep – the strip at the bottom of the door that seals against the threshold; if it is broken or the door has sagged, water can seep under. Third, threshold failure – the threshold (the strip at the bottom of the door frame) can crack, settle, or become unsealed, allowing water to pool and enter. Identifying which of these is the problem tells you which fix is needed.
Quick numbers – cost, savings, and payback for each fix
The table below shows the typical costs and savings for the four most common fixes. All savings figures are based on a typical gas-heated semi-detached home using the 2026 energy price cap, according to DESNZ and the Energy Saving Trust (DESNZ, 2026).
| Fix | Typical Cost (supply & install) | Annual Energy Saving | Payback Period |
|---|---|---|---|
| Replace weatherstripping (DIY) | £10 – £30 | £40 – £60 | Under 1 year |
| Replace door sweep (DIY) | £15 – £40 | £40 – £80 | Under 1 year |
| Replace threshold (professional) | £180 – £450 | £80 – £100 | 2 – 4 years |
| Professional door re-hanging | £100 – £250 | £40 – £80 | 2 – 5 years |
These are estimates based on typical UK trade prices for 2026. Actual costs vary by region and door type.
Replacing weatherstripping is the cheapest fix and pays back in under a year
Weatherstripping is the rubber or foam seal that runs around the door frame. When it is worn, gaps of 1–3mm are common, letting water and draughts through. Replacing it yourself with self-adhesive foam strips costs £10 to £30 from any UK hardware retailer. Professional installation of brush or silicone strips costs £50 to £100. The Energy Saving Trust says draught-proofing a single external door can save £40 to £60 per year on heating bills (Energy Saving Trust, 2026). This means payback is immediate for DIY and within one heating season for professional work.
A new door sweep or threshold is the most effective solution for bottom-of-door leaks
The bottom of the door is where most water enters. A door sweep (also called a bottom seal) costs £15 to £40 for a DIY rubber or brush model, or £50 to £120 fitted professionally. A threshold replacement is more involved. The threshold itself costs £80 to £250 depending on material (aluminium, timber, or composite). Fitting adds £100 to £200. When both are replaced, the Energy Saving Trust estimates combined annual savings of up to £80 to £100 (Energy Saving Trust, 2026). Payback for a sweep alone is under one year. A threshold replacement pays back in two to four years.
Seal the gap at the bottom
The single most common cause of water entry is a gap between the door bottom and the threshold. The fix is to install a new door sweep that contacts the threshold when the door is closed. A quality rubber or brush sweep costs £20 to £50 and can be fitted by a competent DIYer in under an hour. This is the simplest, cheapest, and most effective single action to stop water coming through a door. If the gap is larger than 10mm, a sweep may not be enough and you may need a threshold replacement or door adjustment.
Professional door adjustment or replacement – when DIY won’t work
If the door is sagging, warped, or the frame is twisted, no seal will work permanently. In these cases, professional re-hanging costs £100 to £250. A new standard uPVC door (supply and fitted) costs £600 to £1,200, while a composite door costs £1,000 to £2,000, based on typical 2026 quotes from Checkatrade and MyBuilder (Checkatrade, 2026). Payback on a new door based on energy savings alone is 10 to 15 years. However, the payback is much faster if water damage is prevented, which can otherwise cost thousands to repair. For certified installers of energy-efficient doors, check the MCS register (MCS, 2026). article about composite door costs and payback
How to verify your installer and ensure the work is guaranteed
For any professional work, the installer must be FENSA-registered for uPVC, timber, or aluminium doors, or part of a Competent Person Scheme (GOV.UK, 2026). For composite or timber doors, look for TrustMark accreditation and check the manufacturer’s warranty, which is typically 10 years (TrustMark, 2026). Always get three written quotes and ask for proof of insurance and a written guarantee on the repair or installation. article on how to choose a trusted door installer
Frequently Asked Questions
DIY fixes cost £10–£40 for weatherstripping or a door sweep. A professional threshold replacement costs £180–£450, according to Energy Saving Trust (2026). Re-hanging a door runs £100–£250.
Yes, replacing weatherstripping or a door sweep is a simple DIY job costing £10–£40. The Energy Saving Trust says these fixes pay back in under a year (2026). For a cracked threshold or sagging door, hire a professional.
Three main causes: worn weatherstripping around the frame, a damaged door sweep at the bottom, or a cracked/unsealed threshold. The Energy Saving Trust notes that these gaps also let in cold air, raising heating bills (2026).
A standard aluminium or timber threshold lasts 10–20 years before cracking or settling, according to DESNZ (2026). Signs of failure include water pooling on the doorstep or visible gaps underneath the door.
Yes, draught-proofing an external door saves £40–£100 per year on heating bills, says the Energy Saving Trust (2026). Combined with other draughts, total savings reach up to £125 annually, with DIY costs as low as £10.
