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Buying Guide

Best Draught Excluders for Sash Windows UK 2026

Updated June 2026

Sash windows are beautiful but draughty. The sliding frames create gaps that let cold air pour into your home — you can feel it if you hold your hand near the meeting rail on a windy day. Victorian and Edwardian homes across the UK have original sash windows that have never been draught-proofed. The good news: you can seal them yourself for £15–£30 per window without damaging the original frames.

Quick answer

Our top pick: HNNHOME Brush Strip + BKSAI Window Film

£15–£30 per window on Amazon

For the meeting rail gap: HNNHOME Brush Strip (£8). For the glass: BKSAI Window Insulation Film (£15). For maximum effect: use both (£23 per window). Professional sash window draught-proofing costs £100–200 per window — the DIY approach gives 80% of the result at 15% of the cost.

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Where sash windows let in draughts

  1. Meeting rail — where upper and lower sashes meet (biggest gap).
  2. Sides — between sash frame and box frame.
  3. Bottom rail — gap under the lower sash.
  4. Sash cords and pulleys — channels let air through.

DIY draught-proofing products for sash windows

#1 Meeting rail

HNNHOME 5M Brush Seal Strip

4.4
£7–£105% commission

Brush strips are the best choice for sash windows because they flex with the wood movement as the sash slides up and down. Foam strips compress and tear.

Pros

  • Flexes with sliding sash
  • Self-adhesive — no tools
  • 5m covers 2–3 windows
  • Won't tear like foam

Cons

  • Needs clean dry surface to stick
  • Trim with scissors

Who it's for: The meeting rail where upper and lower sashes overlap.

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#2 The glass

BKSAI Reusable Window Insulation Film

4.3
£12–£185% commission

Covers the entire window with an insulating air layer. Particularly effective on single-glazed sash windows where the glass is the biggest heat loss.

Pros

  • Insulating air layer over whole pane
  • Reusable each winter
  • Renter-friendly velcro fit
  • Best on single glazing

Cons

  • Slight visual haze
  • Trim to fit each window

Who it's for: Single-glazed sash windows where the glass is the biggest heat loss.

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#3 Curtains

Deconovo Triple-Weave Thermal Curtains

4.5
£18–£285% commission

Floor-length thermal curtains in front of sash windows add another insulating layer. Close them as soon as it gets dark.

Pros

  • Adds insulating layer
  • Floor-length blocks cold drop
  • Multiple colours
  • Pair price

Cons

  • Need to close at dusk to work
  • Best with track or pole already fitted

Who it's for: Bedrooms and living rooms with floor-to-ceiling sash windows.

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#4 Fixed gaps

Self-Adhesive Silicone Weather Stripping

4.2
£6–£105% commission

For the bottom rail and sides where the sash doesn't slide. Silicone lasts longer than foam on wooden frames.

Pros

  • Lasts longer than foam on wood
  • Compresses neatly
  • Easy to peel off

Cons

  • Not for the sliding sash itself
  • Cut carefully for tight gaps

Who it's for: Bottom rail and sides where the sash doesn't slide.

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Step-by-step: Draught-proof a sash window

  1. Close both sashes fully and feel for draughts with your hand.
  2. Apply brush strip to the meeting rail (where upper and lower sashes meet).
  3. Apply silicone strip to the bottom rail and any fixed gaps on the sides.
  4. Apply window insulation film over the entire glass area.
  5. Hang thermal curtains for maximum insulation.

Professional vs DIY sash window draught-proofing

MethodCost per windowEffectivenessRenter-friendly?
DIY (this guide)£15–£3070–80% draught reductionYes
Professional draught-proofing£100–£20090–95% draught reductionNeed landlord permission
Secondary glazing£200–£40095%+ draught reductionNeed landlord permission
Double glazing replacement£400–£80099% draught reductionMajor work, listed building issues

Sash windows in rented properties

All DIY products on this page are renter-friendly. Brush strips and silicone strips peel off. Window film uses removable velcro. No damage to original sash frames.

If your sash windows are severely draughty, your landlord may be required to improve them under minimum energy efficiency standards for rental properties.

Buying advice

Tip

Always pick brush over foam for sliding sashes

Foam compresses when the sash closes and tears when it opens. Brush strips flex without damage and last several winters on a typical sash window.

We recommend

Start with the meeting rail

The meeting rail is the single biggest source of draughts on most sash windows. Fix this one gap and you'll feel the difference in the room immediately — before you spend on film or curtains.

Frequently asked questions

Bundle

The Sash Window Draught Kit — Under £30

Total:approximately £31
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