Window styles
Triple glazed sash windows
Sash windows define Victorian and Georgian streets. Modern uPVC and timber sashes slide on spiral balances or weights and lock securely, and many can be triple glazed. Where a heritage design limits the glass thickness, a slim triple or high-performance double unit may give a better result, and we will say so on the quote.
Summary
A sash window has one or two sashes that slide up and down in a box frame. Triple glazed sash windows are made in uPVC and timber, but not every sash design can take a full-thickness triple unit, so the achievable U-value depends on the system and the sash size.
What you get
| Opening | Vertical sliding, top and bottom sashes |
|---|---|
| Frames | uPVC or timber, with horns and run-through sashes available |
| Balances | Spiral balances or traditional weights and cords |
| Glass | Triple where the sash depth allows; slim units otherwise |
| Details | Astragal bars, horns, deep bottom rails |
| Typical lead time | 6 to 10 weeks |
Guide prices
Guide prices per window, supply and fit, including removal of the old window.
Small window
about 600 x 1000 mm (bathroom, landing)
£1,295 – £1,595inc VAT · £1,080 – £1,330 ex VAT
- uPVC frame, triple glazed, warm-edge spacers
- Removal and disposal of the old window
- Fitted, sealed and made good inside and out
Medium window
about 1200 x 1200 mm (bedroom)
£1,695 – £2,095inc VAT · £1,410 – £1,745 ex VAT
- uPVC frame, triple glazed, warm-edge spacers
- Removal and disposal of the old window
- Fitted, sealed and made good inside and out
Large window
about 1800 x 1200 mm (lounge)
£2,595 – £3,195inc VAT · £2,160 – £2,660 ex VAT
- uPVC frame, triple glazed, warm-edge spacers
- Removal and disposal of the old window
- Fitted, sealed and made good inside and out
Guide prices, supply and fit. The written quote after your survey fixes the price for the specification shown; anything extra is agreed with you first.
Is it right for your home?
A good fit for
- Victorian and Georgian terraces
- Replacing draughty, rattling old sashes
- Conservation areas that want the sash look kept
Think twice if
- Listed buildings, where repair or secondary glazing may be required
- Tight budgets, as sashes cost more than casements
Options
- uPVC or timber
- Tilt-in sashes for cleaning
- Slim astragal bars
- Brass, chrome or black fittings
- Restrictors and locks
Can every sash be triple glazed?
No. Some sash systems only accept glass units up to about 24 mm, which is too thin for a well-performing triple unit. A thin triple unit can be worse than a good double unit. We check the system and the sash size, then tell you the whole-window U-value you will get, so you can decide.
Listed homes and sash windows
If your home is listed, replacing original sashes usually needs listed building consent and is often refused in favour of repair. Secondary glazing or a slim replacement unit in the existing sash may be the realistic route. Speak to your conservation officer before ordering anything.
Building Regulations by nation
| Nation | Replacement windows | Sign-off |
|---|---|---|
| England | 1.4 W/m²K, or a Window Energy Rating of band B or better | Competent person scheme or building control |
| Wales | 1.4 W/m²K, or a Window Energy Rating of band B or better | Competent person scheme or building control |
| Scotland | 1.6 W/m²K | No building warrant for a straight replacement; must meet the standards |
| Northern Ireland | 1.6 W/m²K, or a Window Energy Rating of band C or better | No building notice for a straight replacement; must comply |
Full regulations guide, with sources →
Questions about sash windows
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.
Will triple glazing make my sashes heavy to lift?
The balances are sized for the sash weight, so they should slide smoothly. Heavier sashes use stronger balances or weights.
Can I keep my original sash boxes?
Sometimes. A timber specialist can fit new sashes into sound original boxes, but the glass thickness is limited by the sash depth.
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.
Related products
Period homes and conservation areas
From £1,295Heritage-style frames, and straight advice on what your council will accept.
Learn more →
Timber windows
From £1,295Engineered timber frames, factory finished, for period homes and natural looks.
Learn more →
Flush casement windows
From £845Sashes that sit flush in the frame, like traditional timber windows.
Learn more →
Acoustic triple glazing
From £745Laminated acoustic panes and uneven glass for busy roads and flight paths.
Learn more →Sash windows by area
England
- Bedfordshire
- Berkshire
- Bristol
- Buckinghamshire
- Cambridgeshire
- Cheshire
- Cornwall
- County Durham
- Cumbria
- Derbyshire
- Devon
- Dorset
- East Riding of Yorkshire
- East Sussex
- Essex
- Gloucestershire
- Greater London
- Greater Manchester
- Hampshire
- Herefordshire
- Hertfordshire
- Isle of Wight
- Kent
- Lancashire
- Leicestershire
- Lincolnshire
- Merseyside
- Norfolk
- North Yorkshire
- Northamptonshire
- Northumberland
- Nottinghamshire
- Oxfordshire
- Rutland
- Shropshire
- Somerset
- South Yorkshire
- Staffordshire
- Suffolk
- Surrey
- Tyne and Wear
- Warwickshire
- West Midlands
- West Sussex
- West Yorkshire
- Wiltshire
- Worcestershire
Scotland
Sash windows: get your guide price
Use the guide-price tool, or book a free survey for a written quote that fixes the price.