Double Glaze Existing Sash Windows London
If you’ve already had quotes to double glaze your original sash windows in London, would you believe it’s possible to do it for around £500 per window? We can achieve this price through a number of brilliant cost saving options. Rather than entirely replacing the sashes, we will make use of them. We remove the original glazing and putty exposing the old timber rebate. We then use this rebate by deepening it and widening it with a purpose made router bit. This offer the chance to neatly install a double glazed unit in place of the single glazed. Most sashes are able to carry a double glazed unit but they must be in reasonably good structural condition to manage the extra weight. Once the old rebate is made to accept the double glazed unit we use a quality silicone that will not break to bed the unit. An external timber glazing bead is then applied in place of putty to improve the external finish. In most cases where putty is not in perfect condition this will improve the look of your windows. It is also impossible from ten metres to see your windows have been double glazed looking straight on at them.
When original sashes can't hold a double glazed unit
If your windows are not capable of holding a double glazed unit within the original sash then the next best option is to have the sashes replaced and make use of the existing frame. This service costs around 25-40% more than double glazing of existing sash windows but is still excellent value for money when considered against entire sash window replacement. This service works out to be half the price of entire replacement and in most cases almost equally as efficient at noise and heat retention. Double glazing alone is not enough, windows must be draught proofed as well in order to get the most from this service.
Full replacement — the last resort
We do offer full double glazing of sash windows in London and we supply the entire window replacements fully decorated with the most up to date security options. It is not a service we push at client, we will always try to make use of existing joinery where possible, despite onsite work being more difficult and less comfortable, it is the correct thing to do for homeowners of London.
Three routes to a double-glazed sash window
Route 1 — Double glaze the original sash
From £480 per window. We rebate the existing sash and bed a Pilkington low-E unit. Usually invisible from the street.
Route 2 — New sash in the original frame
From £680 per window. A like-for-like sash with a double-glazed unit, fitted into your existing box frame.
Route 3 — Full replacement
From £1,480 per window. Hardwood or softwood, full decoration and modern security — but only when repair isn't viable.
Double glazing vs secondary glazing in London
If you're in a conservation area or listed building, retro-fitting double glazing into your originals is usually the best compromise. Secondary glazing is fully reversible and often preferred by conservation officers; double glazing offers better aesthetics and is what most London homeowners ask us for. We'll advise on the right route for your property.
Get a free quote
Call 020 3441 6515 or email support@sashwindowsrepairlondon.co.uk. We quote fairly, in person where possible, and stand behind our work with a five-year guarantee.