Sash Windows across the UK

Sash Windows - what to expect

Sash windows suit period properties - Georgian, Victorian and Edwardian houses in particular - where a casement would look wrong. Modern double-glazed sashes replicate the classic vertical-sliding design while cutting heat loss by 60-70% versus single-glazed originals.

You have two real choices: a full replacement in uPVC or timber, or a sympathetic refurbishment where the original box and sashes are kept but slim-profile double glazing is fitted into the existing frames. Refurbishment is often the only route in listed buildings or strict conservation areas, and typically costs 30-50% more than a like-for-like uPVC replacement.

Slim double glazing (10-14mm units) exists specifically for sash windows and looks close enough to single glazing that most councils accept it in conservation areas - but it performs worse than standard 28mm units, so weigh visual authenticity against U-value carefully. Timber sashes with slim glazing sit around 1.6 W/m²K; uPVC sashes with a standard 28mm unit hit 1.2 W/m²K or better.

Typical UK price range for sash windows: £600 - £1,100 installed. Actual figures for your city sit on the city page below.