Sash windows · Greater London
Triple glazed sash windows in Harrow
Looking at triple glazed sash windows for a home in Harrow? We survey, quote and fit across Greater London, and the HA2 postcode district is part of that.

Honest advice on which sashes can take a full triple unit. A sash window has one or two sashes that slide up and down in a box frame.
Winter light and glass choice in Harrow
On the shortest day, Harrow gets about 7 h 49 min of daylight and the midday sun reaches only about 15° above the horizon. Low winter sun means north-facing rooms here gain little solar heat, which is where triple glazing’s lower heat loss helps most.
Guide prices in Harrow
| Guide | Supply and fit, inc VAT |
|---|---|
| Small window about 600 x 1000 mm (bathroom, landing) | £1,295 – £1,595 |
| Medium window about 1200 x 1200 mm (bedroom) | £1,695 – £2,095 |
| Large window about 1800 x 1200 mm (lounge) | £2,595 – £3,195 |
Guide prices. Your written quote after the free survey fixes the price for the specification shown.
Rules for sash windows in England
England requires replacement windows to achieve 1.4 W/m²K, or a Window Energy Rating of band B or better, which good triple glazing passes comfortably. Replacement windows are a controlled fitting. A competent person scheme installer (such as FENSA or Certass) self-certifies the work and notifies the council within 30 days; otherwise a building control body approves it.
Before ordering: Replacing windows on a house is normally permitted development if the new ones look similar. New upper-floor windows in a side wall must be obscure glazed and fixed, or open only above 1.7 m. Flats and maisonettes have no householder permitted development rights, so a change that alters their appearance needs planning permission. An Article 4 direction in a conservation area may mean permission is needed, and listed buildings need listed building consent.
How it works
After the free survey you get a written quote naming the frame system, the glass build-up and the whole-window U-value for every item. Windows are made to order, then fitted, sealed and made good, one opening at a time.
- Every opening measured, including escape and vent needs
- Frames rated for the weight of triple glass
- Old windows removed and taken away
- Each opening closed up the same day
Questions from Harrow
How much do triple glazed sash windows cost?
Our guide starts at £1,295 for a small uPVC sash, fitted and inc VAT. Timber sashes cost more; UK quotes for timber triple sashes run past £3,000 each.
Are uPVC sashes allowed in conservation areas?
It depends on the council and any Article 4 direction. Timber is often expected on front elevations. Check before ordering.
Do I need permission for triple glazed sash windows in Harrow?
In England, like-for-like replacements on a house are normally permitted development; flats need permission if the change alters their appearance, Article 4 areas may need permission, and listed buildings need listed building consent. Check whether your street is in a conservation area or covered by an Article 4 direction before changing the style.
Do you fit triple glazed sash windows in Harrow?
Yes. We arrange surveys and fitting in Harrow and across Greater London. Send your postcode and the windows or doors you want replaced, and we will book a free survey.
Nearby
Also near Harrow: Wembley (4 km), Northolt (4 km), Greenford (6 km) and Ruislip (6 km).
Other products in Harrow
- uPVC windows
- Aluminium windows
- Timber windows
- Alu-clad timber windows
- Casement windows
- Flush casement windows
- Tilt and turn windows
- Bay and bow windows
- Fixed and picture windows
- Composite front doors
- French doors
- Sliding patio doors
- Bifold doors
- Glass-only replacement
- Acoustic triple glazing
- Security glazing
- Whole-house replacement
- New builds and self-builds
- Period homes and conservation areas
- Flats and apartments
- Passivhaus and EnerPHit
Sash windows in Harrow: book your free survey
Written quote fixed for the specification, after a free survey. Building Regulations sign-off by a competent person scheme installer or building control, as the law requires in England.
