Double glazing upgrade
Double glazing for your sash windows, without replacing the whole window.
Your original case stays in the wall. We manufacture new slimline double glazed sashes to match the existing sections and sight lines — modern warmth and quiet, with nothing changed to the eye. It is an approach councils will consider for listed buildings, with consent.
How it works
New sashes, original case
Replacing a whole window means losing original timber and disturbing stonework, and in a listed building the council will expect evidence that the window is beyond repair. Upgrading the sashes avoids the first two, and is usually an easier case to make to the council. We measure your existing case, then manufacture new timber sashes in our Glasgow workshop with slimline double glazed units, matched to the original mouldings, astragals and sight lines.
The new sashes are hung on new cords with rebalanced weights, draught proofing is fitted as standard, and the whole window is decorated inside and out. From the street, nothing has changed. From your armchair, everything has.
The consent rules differ between councils. See double glazed sash windows in Glasgow and in Edinburgh for what applies in each city.
- Existing case, architraves and shutters all stay in place
- Slimline double glazed units in new timber sashes, made to match
- Aquamac draught proofing with a lifetime guarantee, included
- Brass or chrome fittings, security locks and simplex hinges for easy cleaning
- Full decoration inside and out, included as standard
- A 10 year guarantee on the new sashes
What you will notice
The difference double glazing makes
Warmth
Double glazed units and sealed sashes hold heat that single glazing lets straight out — rooms that finally stay warm, and heating bills that show it.
Quiet
Traffic, seagulls and late night passers by fade behind two panes and a sealed frame. Customers tell us the soundproofing surprises them more than the warmth.
Nothing changed to the eye
Slim units sit in timber sashes made to the original profiles. From the street, neighbours will not notice the difference.
Easy cleaning
Brass simplex fittings let the sashes swing inward, so upper floor windows can be cleaned safely from inside — what Scottish building standards expect for windows more than 4 metres above the ground.
★★★★★
“We had all our windows replaced with narrow gauge double glazed sash windows which swung inside for easy cleaning in our tenement building. They were excellent quality, so much so, our neighbour had theirs done too. Those windows sold our flat.”
★★★★★
“Their craftsmanship is outstanding and the team were a pleasure to work with. I have eleven new sash windows that have changed my flat completely in terms of soundproofing, heat retention and visual appeal.”
Common questions
Double glazing period windows
Is this allowed in a listed building or conservation area?
Often, yes, with permission. In a listed building, new double glazed sashes need listed building consent, and councils look for slim units in sashes that match the original profiles and sight lines. Edinburgh's guidance lists new sashes in existing cases among the options it will consider. In a conservation area, front windows that change in appearance need prior approval. We have worked with conservation authorities across Scotland for more than thirty years and help with the consent application, drawings included. See our listed building guide.
Will the windows look different afterwards?
No. The new sashes are made to the original profiles, mouldings and astragal patterns, and the units are slimline, so the glazing lines match what was there before. From outside, the window looks as it always has.
Can you double glaze just some of the windows?
Yes. Every window is surveyed and quoted individually, so you can upgrade street facing rooms and simply refurbish the rest — many customers phase the work room by room.
Can I get help paying for double glazing?
We do not offer finance ourselves, but help is often available. Home Energy Scotland offers interest free loans of up to £8,000 for replacing single glazing with double glazing, where your home's energy certificate recommends it. You must have Home Energy Scotland's written offer before any work starts. See funding for sash windows in Scotland, and what to expect once the work is under way.
Warm house, original windows. You can have both.
Surveys are free, quotations are written and itemised, and there is never any obligation.
Arrange a free survey
Not sure whether to restore, upgrade or renew? Let us have a look.
Tell us a little about your windows, with a photo or two if you have them, and we will call you back to arrange a visit.
You enquire
Send the form, with photos if you have them, or phone us. We aim to call you back the same working day.
Free survey
We visit at a time that suits you and assess every window individually.
Written quote
A clear, itemised quotation with no hidden extras — and never any obligation.