Draught-Proofing a Front Door: Cost and Methods

The short answer

Draught-proofing a front door typically costs anywhere from a few pounds for basic self-adhesive foam strip to £40-£80 for a proper brush or compression seal kit professionally fitted, plus a similar amount again for a letterbox draught excluder and a keyhole cover if needed. It's one of the cheapest, fastest-payback energy improvements available for a UK home, and — unlike loft or wall insulation — most of it is realistic to do yourself in an afternoon.

Where front door draughts actually come from

There are usually four places to check: around the door frame where it meets the surrounding wall (a sealing issue, not a door issue), the gap between the door and frame edges (needs a compression or brush seal), the gap under the door (needs a threshold or door-bottom seal), and the letterbox and keyhole, which are surprisingly significant sources of draught on many older doors with basic flap letterboxes and no keyhole cover.

Sealing the door edges

For a door that's a reasonable fit in its frame, self-adhesive foam or rubber strip pressed into the gap between door and frame is the cheapest option, but tends to compress and lose effectiveness within a year or two. A better long-term option is a proper compression seal (a sprung strip fitted into a groove routed into the frame) or a brush seal, both of which last considerably longer and perform better — these are usually worth having professionally fitted unless you're confident working with a router or have a door specifically designed to accept a retrofit seal.

Sealing the bottom of the door

A door-bottom draught excluder (a brush or flexible seal fitted to the inside face of the door, or a threshold seal fitted to the floor) closes the gap under the door — often one of the biggest single sources of draught, especially on older doors fitted with a generous clearance for the (now often replaced) carpet or flooring underneath. Automatic drop-down seals, which lift clear when the door opens and drop to seal when closed, are a more polished but pricier option than a fixed brush strip.

Letterbox and keyhole

A letterbox draught excluder — either a brush-lined flap retrofitted to the existing letterbox, or a dedicated internal box with a spring-loaded flap — meaningfully reduces draught through what's often an overlooked gap. A simple sprung keyhole cover does the same for the keyhole on doors that have one, at minimal cost.

Sealing around the frame itself

If the draught is coming from around the outside edge of the frame — where it meets the surrounding brickwork or render, rather than where the door meets the frame — the fix is different: check and, if needed, re-seal the gap with an appropriate exterior-grade sealant. This is the same underlying issue covered in our guide to why windows go draughty, and the diagnosis approach is similar for a front door.

Costs at a glance

• Self-adhesive foam strip: a few pounds, DIY, lasts 1-2 years before needing renewal.
• Brush or compression seal kit: roughly £15-£40 for materials, more if professionally fitted (£40-£80 all in), lasts considerably longer.
• Letterbox draught excluder: roughly £10-£25.
• Automatic threshold/drop-down seal: roughly £20-£50 for the part, more with professional fitting.

Common mistakes

• Only sealing the obvious gaps and missing the letterbox/keyhole. These are easy to overlook but genuinely significant on many older doors.
• Using cheap foam strip on a door that gets frequent use. It compresses and stops sealing effectively faster than a proper brush or compression seal — fine as a quick fix, not ideal as the only long-term solution.
• Sealing a door so tightly it becomes hard to close. A small amount of adjustment (or professional fitting) usually avoids this — a door that won't close properly creates its own problems.

Is it worth it compared to a new door?

For most doors in otherwise reasonable condition, draught-proofing is a fraction of the cost of full replacement and addresses the great majority of the heat-loss problem. A new door (see our comparisons of composite vs uPVC doors, if you're weighing that up) is worth considering when the door itself is genuinely worn out, damaged, or performing poorly regardless of sealing — not as the default first step for a draughty but otherwise sound door.