Best Letterbox Draught Excluder for External Doors: 2025 Expert Review
DR Joinery
Expert Joiner & Door Specialist
Walking into a hallway and feeling an icy breeze cutting through the front door is a common grievance in York, particularly in our older terraced properties. The letterbox is often the biggest culprit for heat loss, acting like a funnel for the wind if not properly sealed.
Many homeowners attempt to fix this with cheap tape or foam, but these rarely last. As a professional joiner, I always advise that a properly fitted draught excluder is one of the most cost-effective ways to improve your home's thermal efficiency. It protects the timber from moisture ingress and keeps your heating bills down.
In this review, I'll compare three specific solutions I've encountered: a simple brush surface-fix for those on a budget, a premium telescopic sleeve for a complete door upgrade, and a larger oversized unit designed to cover messy existing holes.
Live in York?
Is your front door letting in the cold?
Get a free quote from our local team.
Specs vs. The Real World
The Spec: "Universal Fit"
"Manufacturers often claim their letterplates fit all doors regardless of material or thickness."
In joinery, nothing is truly universal. A Victorian timber door is a different beast to a modern composite. You must check the door thickness (midrail depth) and ensure the aperture matches, otherwise, you'll be chising out wood or left with unsightly gaps.
The Spec: "100% Draught Proof"
"Marketing suggests a simple brush will stop all air movement."
Brushes stop the 'whistle' and light breezes, but for the driving wind we get in Yorkshire, you really need a solid flap combined with stiff brushes (a double seal) to make a noticeable difference to the room temperature.
My Top 3 Recommendations
Three options to cover different needs and budgets
Internal Letter Box Draught Excluder Cover With Brushes & Flap - White PVC
STORMGUARD
For a quick, no-nonsense fix, this Stormguard unit is effective. It's a surface-mounted solution, meaning you don't need to remove your external letterplate. It simply screws onto the inside of the door, adding a layer of brushes and a plastic flap to reduce airflow.
The Good
- Very affordable option for immediate results
- Easy surface-mounted installation (no complex cutting)
- Double protection: brushes strip the wind, flap adds a barrier
The Bad
- PVC construction can feel a bit 'plasticky' compared to metal fittings
- The bristles can deform over time if heavy post is forced through regularly
Installer Tip:
When fitting this to a wooden door, always pilot drill your screw holes first. Old timber can be surprisingly brittle, and driving a screw straight in can split the grain, ruining the finish of your door.
Priced at £5.29 at the time of writing
Check Price on AmazonXfort MailPlate 12" Letterplate Matt Black, Premium Draught Proof Postal Letterbox
UAP
This is a full replacement unit rather than just a cover, and it's the sort of quality fitting I'd recommend for a proper door renovation. The telescopic sleeve lines the inside of the door hole, which prevents moisture from getting into the door's core—vital for composite doors or solid timber sandwich construction.
The Good
- Telescopic sleeve seals the door core completely
- Premium matt black finish suits both modern and heritage properties
- Anti-snap flaps open 180 degrees (great for clumsy posties)
The Bad
- Requires removing the old letterbox entirely
- Installation requires more precision to align the internal and external sleeves
Installer Tip:
The sleeves telescope independently. Before tightening the screws, ensure both sides are pinched tight against the door face to compress the gasket seal. If your door is thinner than 40mm (common on old interior vestibule doors), you might need to trim the plastic sleeve down with a hacksaw.
Priced at £15.99 at the time of writing
Check Price on AmazonInternal Letterbox Draught Excluder 13.5 Inch (34.2cm) PVC Draught Letter Plate Seal
ZAVIA
Sometimes, when you remove an old letterbox, you find the previous owner cut the hole with a blunt spoon or the paintwork is ragged. This Zovia unit is slightly larger (13.5 inches), making it perfect for covering up unsightly edges or oversized apertures that standard excluders can't hide.
The Good
- Extra width covers chipped paint or rough joinery work
- Clean, modern design updates the look of the door instantly
- Good thermal seal reduces energy bills
The Bad
- Large footprint might not fit if your door has narrow panels or moulding
- White PVC might clash if you have antique brass fittings elsewhere
Installer Tip:
Because this unit covers a large area, uneven door surfaces can cause gaps around the edge. I recommend running a very thin bead of clear silicone or decorators caulk along the back edge of the frame before screwing it tight. This stops air leaking in behind the frame itself.
Priced at £10.99 at the time of writing
Check Price on AmazonFrequently Asked Questions
Do draught excluders really help with heating bills?
Can I fit a letterbox draught excluder to a uPVC door?
What is the difference between a letterplate and a draught excluder?
Why do the brushes on my old excluder not touch anymore?
Need Professional Internal & External Door Fitting?
Our team at DR Joinery specialises in Internal & External Door Fitting across York.
Get a free quote for professional installation.
View Our Internal & External Door Fitting Service