A front door draught can lose heat equivalent to a £45 annual electricity bill
A draughty front door pulls cold air into your home and forces your heating system to work harder. The Energy Saving Trust estimates that a single draughty front door in a typical semi-detached house can increase heating demand by up to 10% (Energy Saving Trust, 2026). That extra demand translates into roughly £45 of wasted heat per year on a gas-heated home.
To put that into perspective, the average annual running cost of a fridge freezer is around £55 (Ofgem, 2026). Your front door draught is therefore costing you nearly as much as keeping a major appliance running all year. Fixing it is one of the cheapest energy-efficiency improvements you can make.
How to identify the exact source of your front door draught
Draughts can enter through several points around a front door. The most common sources are the bottom gap under the door, the letterbox, the keyhole, gaps between the door frame and the wall, and failed pane seals on glazed doors. Each source requires a different type of seal.
The simplest way to locate the draught is a visual inspection. On a windy day, hold a lit incense stick or a sheet of paper along the door edge. If the smoke wavers or the paper flutters, you have found a leak. GOV.UK recommends this method as a reliable first step in draught-proofing a home (GOV.UK, 2026). Work methodically around the entire perimeter, including the letterbox and keyhole.
The three most common draught points and their typical fix costs
The table below shows the three most frequent draught points, the materials typically used to seal them, and the approximate cost for a DIY fix versus a professional installation. Prices are based on 2026 industry data from the Energy Saving Trust and Checkatrade (Energy Saving Trust, 2026).
| Draught Point | Typical Material | DIY Fix Cost (GBP) | Install Cost (GBP) |
|---|---|---|---|
| Bottom gap | Door sweep / threshold seal | £8–£20 | £40–£80 |
| Letterbox | Brush seal / letterbox cover | £5–£15 | £25–£50 |
| Perimeter frame gap | Foam strip / silicone seal | £5–£15 | £30–£60 |
The simple fix that stops 90% of front door draughts (the featured-snippet answer)
Installing a brush-strip door sweep to seal the bottom gap is the single most effective fix for a front door draught. The bottom gap is responsible for the majority of cold air ingress because it is the largest opening and sits at floor level where cold air sinks. A brush sweep blocks this channel without preventing the door from closing properly.
To fit one, measure the width of your door, cut the sweep to length using a hacksaw, and screw it to the bottom edge of the door on the inside face. The brush should make light contact with the floor or threshold. The Energy Saving Trust provides a step-by-step guide for this process (Energy Saving Trust, 2026). MCS-certified installer guidance also confirms that this fix resolves the vast majority of front-door draught issues (MCS, 2026).
How to check if your front door needs replacing instead of fixing
Seals and sweeps will not solve a door that has structural problems. If the door is warped, has rotten timber at the base, or the frame is no longer square, replacement may be more cost-effective than repeated repairs. A simple test: close the door on a £5 note. If you can pull the note out without resistance, the seal is failing. This test works for both the bottom edge and the perimeter.
Another indicator is the door’s U-value, which measures how quickly heat passes through the material. A modern insulated door typically has a U-value below 1.6 W/m²K, while an old uninsulated door can exceed 2.2 W/m²K (DESNZ, 2026). If your door has a U-value above 2.2, replacing it with a FENSA-compliant door will save more energy than any seal can deliver (FENSA, 2026).
What to look for when hiring a draught-proofer or installer
For a simple DIY fix like fitting a door sweep or letterbox brush, any competent handyperson can do the work. However, if you need a new door, a complex threshold seal, or work on a glazed panel, you should use a certified installer. The TrustMark scheme registers tradespeople who meet government-endorsed standards for quality and customer protection (TrustMark, 2026).
For a full door replacement, MCS certification is relevant for energy-performance guarantees, though not legally required for standard doors (MCS, 2026). Always ask for public liability insurance and a written quote that itemises materials and labour. Avoid paying the full amount upfront.
The long-term savings from fixing your front door draught
Fixing all draughts on a typical front door saves between 50 and 100 kWh of heat per year, worth £10 to £20 on a gas-heated home at 2026 rates (Energy Saving Trust, 2026). That is a modest saving on its own, but it compounds when you draught-proof other areas such as windows, the loft hatch, and letterboxes on other external doors. Combined, these measures can save £60 to £90 annually.
The cost of a door sweep and letterbox brush is typically under £30, meaning you recover the investment within two years. Over a decade, the total saving from fixing a single front door draught can exceed £200.
