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Best Letterbox and Keyhole Draught Excluders for a Warmer, Quieter Hallway
A letterbox is one of the biggest gaps in an otherwise sealed front door, and a keyhole adds a second leak that most weatherstripping kits ignore. This roundup covers five letterbox and keyhole draught excluders that close those gaps without blocking the post, ranging from simple internal covers to a full replacement letterbox for uPVC doors.
It suits three groups: renters who need a no-drill fix, homeowners upgrading a tired flap on a composite or wooden door, and anyone chasing a cold hallway or a whistling draught on windy nights. The overview below shows each pick’s key spec and best use so a choice can be made in under a minute.
The Picks at a Glance
| Product | Key Spec | Best Use | Price Tier |
|---|---|---|---|
| STORMGUARD Internal Letter Box Draught Excluder Cover | PVC cover with brushes and flap | Budget internal fix | Budget |
| Merriway BH05982 StormSeal Letter Mail Box Brush Cover | 343 x 80mm, internal or external | Versatile all-rounder | Mid |
| Letter Box Cover Draught Excluder, Silver Finish | Silver-finish internal cover | Matching metal hardware | Mid |
| Keypak 12" Adjustable Letterbox | 20–40mm doors, anti-snap flap | Replacing a whole letterbox | Premium |
| White Letter Box Draught Excluder with Cover Flap | White cover with flap | Simple white-door match | Budget |
1. STORMGUARD Internal Letter Box Draught Excluder Cover with Brushes & Flap — White PVC
Type: Internal letterbox cover
Material: PVC
Colour: White
Build: Brush seals plus closing flap
Intended use: Indoor face of the door
STORMGUARD Internal Letter Box Draught Excluder Cover with Brushes & Flap – White PVC
The STORMGUARD cover mounts on the inside face of the door and uses two layers of defence: a set of brushes that the post pushes through and a flap that drops shut behind it. The white PVC body is light, easy to wipe down and unobtrusive against a painted door. It is the classic first buy for a draughty hallway because it needs no special tools and no changes to the outer door furniture.
This is the pick for renters and for anyone who wants the cheapest possible fix before committing to a bigger job. It also suits doors where the outside letterbox is fine but the inside still whistles. The trade-off is that a PVC cover at this price is built for light duty, so heavy daily post and thick catalogues will wear the brushes and flap sooner than a metal unit would.
2. Merriway BH05982 StormSeal Letter Mail Box Brush Cover Draught Excluder with Flap
Type: Letterbox brush cover with flap
Size: 343 x 80mm (13.1/2 inch x 3.1/8 inch)
Material: Brush seal with flap
Colour: White
Intended use: Internal or external
The Merriway is the flexible option: the same unit is rated for either side of the door, so it can face the weather outside or sit indoors. Its stated 343 x 80mm footprint fits a standard letterplate opening, and the brush curtain plus flap arrangement lets post through while closing the gap behind it. The white finish keeps it neutral on most door colours.
This pick earns its place for buyers who are not sure which side of the door the leak is on, or who want one product that covers both cases. It is also the sensible choice for a shed, garage side door or back door where a matching aesthetic matters less. The trade-off is that a dual-use cover is a compromise on both fronts: it is not as weatherproof as a purpose-built external hood, and it is bulkier indoors than a slim internal-only cover.
3. Letter Box Cover Draught Excluder for Internal Use — Silver Finish
Type: Internal letterbox cover
Finish: Silver
Intended use: Indoor face of the door
Build: Cover with draught-blocking seal
Letter Box Cover Draught Excluder for Internal Use – Silver Finish
This cover is the cosmetic upgrade of the group. The silver finish is designed to sit against chrome or brushed-metal door furniture, letterplates and handles rather than disappear into a white door. It mounts internally, so the outer face of the door stays untouched and the street-facing look is unchanged.
It suits buyers with a modern door, a metal letterplate or a hallway where white plastic would stand out. The silver tone also hides scuffs better than plain white over time. The trade-off is that a metal-look finish on an internal cover shows fingerprints and dust more readily than matte plastic, so it needs a wipe now and then to keep looking sharp.
4. Keypak 12" Adjustable Letterbox — 30.6cm Sleeved Letterbox for uPVC, Composite and Wood Doors
Type: Sleeved replacement letterbox
Length: 30.6cm (12 inch)
Door thickness: 20–40mm
Flap: Anti-snap
Colour: Black
Intended use: uPVC, composite and wood doors
The Keypak is the only true replacement in this roundup. Instead of bolting a cover over an existing letterplate, it swaps the whole unit for a sleeved letterbox that passes through the door. The adjustable sleeve is stated to fit doors from 20mm to 40mm thick, which covers most uPVC, composite and timber doors, and the anti-snap flap is built to resist being forced.
This is the pick for a front door where the old flap rattles, sticks or has lost its seal, and for anyone who wants a cleaner look than a bolt-on cover. The black finish suits modern composite doors well. The trade-off is that fitting requires removing the old letterplate and trimming the sleeve to the door thickness, so it is a screwdriver-and-saw job rather than a peel-and-stick one.
5. White Letter Box Draught Excluder with Cover Flap
Type: Internal letterbox cover with flap
Colour: White
Build: Cover with closing flap
Intended use: Indoor face of the door
White Letter Box Draught excluder with Cover Flap
This is the simplest product here: a white internal cover with a flap that closes over the opening. There are no brushes to clog and nothing to adjust, which makes it the easiest of the five to live with day to day. The plain white design blends into a standard white uPVC or painted internal door.
It suits buyers who want the lowest-fuss fix and a tidy look, and it works well as a second cover on a door that already has an external letterplate. The trade-off is that a flap-only design relies entirely on the flap seating flat, so a warped door or a badly positioned letterplate will leave gaps that a brush seal would have caught.
Before You Buy
- Material: PVC and plastic covers are cheap and light but wear faster; metal-look and sleeved units last longer and resist knocks.
- Size: Measure the existing letterplate opening before ordering — the Merriway’s stated 343 x 80mm is a typical reference point.
- Door thickness: Only a sleeved replacement such as the Keypak needs this; its stated 20–40mm range covers most uPVC, composite and timber doors.
- Internal vs external: Internal covers are the easy fix; external-rated units must cope with rain and wind, so check the rating before fitting outside.
- Fitting method: Bolt-on covers need only a screwdriver; a full replacement letterbox needs the old plate removed and the sleeve trimmed.
- Care: Brushes collect dust and hair over time, so plan on brushing them out occasionally to keep the seal tight.
- Keyholes: Pair a letterbox cover with a separate keyhole cover or escutcheon, since a letterbox unit alone will not seal the keyhole.
Frequently Asked Questions
-
Do letterbox draught excluders actually stop draughts?
Yes, when fitted flush over the opening. Brushes and flaps block the airflow path, but a badly seated cover or a warped door will still leak. -
Can a letterbox cover be fitted to a uPVC door?
Bolt-on internal covers can be screwed to uPVC with self-tapping screws. A sleeved replacement like the Keypak is designed for uPVC doors and adjusts to the door thickness. -
What about the keyhole?
A letterbox cover seals only the letter opening. A separate keyhole cover or escutcheon is needed to close the keyhole gap, and the two are usually bought together. -
Will a cover stop the letterbox rattling in the wind?
In most cases yes, because the flap rests against the cover instead of the metal plate. A worn or loose existing letterplate may need replacing rather than covering. -
Can a cover be used on the outside of the door?
Only if it is rated for external use, like the Merriway StormSeal. Internal-only covers will degrade in rain and sunlight. -
How long do the brushes last?
It depends on post volume. Light household mail gives years of service; heavy daily catalogues wear brushes faster and they may need replacing.
Bottom Line
For most homes, the Merriway BH05982 StormSeal is the safest single buy: its stated 343 x 80mm size fits standard openings and it works on either side of the door. Buyers replacing a worn-out letterplate outright should go straight to the Keypak 12" adjustable sleeved unit, while a tight budget points to the STORMGUARD PVC cover. Whichever fits the door, check the current price before ordering.