Sash window specialists since 2008 · All of Hertfordshire
Sash window repair and reglazing with vacuum double glazing in Hertfordshire
We repair your original sashes and fit slim double glazing into them — in Hertford, St Albans, Watford, Hitchin, Stevenage, Bishop’s Stortford, Royston and across the county.
- Warmer rooms, lower bills — slim double glazing in your existing sashes
- No more draughts or rattles — draught-proofing, new cords and weights
- Rot cut out, not painted over — replaced in rot-resistant Accoya timber
- Listed homes and conservation areas welcome — the look stays original
Free, no-obligation quote · minimum 5 windows · from £650 a window
Before After What customers say
Is this happening to your windows?
Old sash windows usually fail from the bottom up. The sill and the bottom rail of the sash take most of the rain, so that is where rot tends to start. Putty dries out and falls away. Cords snap, and the gaps around the sashes open up and let the cold in.
Rot keeps spreading if it’s left, but a rotten window rarely needs replacing. We cut out the soft timber and splice in new Accoya, fit new cords and weights, and draught-proof the sashes. If a room still feels cold after that, we can fit slim vacuum glazing into the same sashes.
Because the windows look the same afterwards, like-for-like repairs don’t need planning permission. That helps in towns like St Albans, Hertford, Hitchin and Bishop’s Stortford, where many houses are listed or in a conservation area.
Below are the common problems and what we do about each one.

Rotten sills
Rot cut out, new Accoya timber spliced in

Rotten beading
New staff and parting beads, with weather-stripping

Cold draughts
Draught-proofing seals around every sash

Rotten frames
Frames repaired in Accoya, with a 20-year guarantee

Cracked glass
New glass, or slim double glazing

High heating bills
Slim double glazing in your existing sashes

Loose or missing putty
Reglazed and sealed

Outside noise
Slim double glazing cuts the noise

Stuck or rattling sashes
New cords and rebalanced weights

Condensation
Slim double glazing and draught-proofing
BeforeAfterRestore or replace?
When wooden windows are weathered and damaged, replacing them can look like the only option. It isn’t: even badly decayed windows can be repaired and brought back to full working order.
- Costs less than new windowsRestoring is cheaper and quicker than having new timber windows made and fitted.
- Keeps your home’s characterYour original sashes, glazing bars and mouldings stay where they are.
- The greener choiceWindows you already have are kept in use instead of replaced.
Before and after: our work
Photos from our own jobs, taken before we started and after we finished. Tap a pair to see it larger.
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Rotten sill cut out and replaced
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Frames repaired, broken panes replaced with double glazing
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French doors repaired and double glazed
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A curved sash window sill rebuilt
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A sash window fully restored
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Bay window restored and double glazed
Two ways we fix them
Restoration and repair
We cut out the rot and splice in new Accoya timber, fit new cords and weights, free stuck sashes and fit draught-proofing seals. Your windows keep their original timber and look.
20-year guarantee on timber repairs
From £650 a window · typically £770–£910
How we repair sash windowsRestoration plus slim double glazing
Everything in the restoration and repair package, plus new glass. We take out the single panes and fit vacuum glazing only 8 mm thick into your original sashes. The frames stay, and so does the look.
15–25-year guarantee on the glazing, 20 years on the timber repairs
From £1,050 a window · typically £1,050–£1,550, the full restoration included
How double glazing your sashes worksMinimum order: 5 windows. See the full price guide.
How we repair sash windows in Hertfordshire
Weather wears older windows down: the wood rots, and the finish cracks and lets moisture in. We repair sash and casement windows, front and French doors, so they work and look as they should.
- Rot in frames and sashes repaired in Accoya and Tricoya timber
- New sash cords and rebalanced weights
- Stuck and painted-shut windows freed
- Cracked or broken glass replaced
- Draught-proofing seals around the whole window
- New locks and extra security
- Sashes adjusted to take new glazing units
Many of the houses we work on in Hertfordshire are listed, like the Grade 2 listed homes in Sawbridgeworth and Barley further down this page. There we keep as much of the old timber as we can and replace only what has rotted.
20-year guarantee on every timber repair
BeforeAfterHow we double glaze existing sash windows in Hertfordshire
Vacuum double glazing is only 8 mm thick, so it fits the slim rebate of a period sash. It insulates as well as standard triple glazing.
No new windows and no bulky secondary glazing: we fit the vacuum units into your existing wooden sashes, so your double glazed sash windows keep their original look, Georgian bars included. The sashes get the full restoration at the same time: rot repairs, new cords and weights, and draught-proofing.
- Warmer rooms and lower heating bills
- Less outside noise
- Better security
- No more cold draughts
Recent work in Hertfordshire
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Transformation and restoration in Sawbridgeworth
A Grade 2 listed house with rot in its casement windows, doors and timber cladding. We cut out the rotten sections and repaired them in Accoya, so nothing had to be replaced.
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Extensive repairs to wooden windows in Barley
Another Grade 2 listed house, restored on a recommendation. Only the rotten parts were replaced, in Accoya and Tricoya, and we kept as much of the old timber as we could.
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Sash window refurbishment in Hertfordshire
A listed period home with rot in many of its windows. Some upper sashes came out and went back in on the same day, and all the joinery was done on site in our mobile workshop.
What happens after you get in touch
- 1
Send us photos
Email photos of your windows, with how many windows there are and your full address, to:
- 2
We send you an estimate
A price estimate for your windows, usually within 15% of the final price, so you know where you stand before anyone visits.
- 3
We meet for the quote
We look at the windows with you, then email you the final quote within three days.
Questions Hertfordshire homeowners ask
How much does it cost in Hertfordshire?
Restoring a sash window starts at £650, and an average-size sash usually costs £770–£910. With slim double glazing it starts at £1,050 a window, usually £1,050–£1,550, and that price includes the full restoration: rot repairs, new cords and weights, and draught-proofing. The minimum order is 5 windows.
Can you work on a listed building or in a conservation area?
Yes, we regularly do. Like-for-like timber repairs don’t need planning permission, because the windows look the same afterwards. Double glazing a Grade 2 listed building does need permission, so apply for it before any work starts. More on listed buildings.
My windows are rotten. Can you still double glaze them?
Yes. We repair the frames first: the rotten parts come out and new solid Accoya timber goes in, then the new glass is fitted.
How long does double glazing take?
The vacuum glass is made to order, and at the moment it takes 8–16 weeks from order to delivery. We fit it into your windows as soon as it arrives.
Do you take the windows away?
No. We do all the work on site, in our mobile workshop.
What does the 20-year guarantee cover?
All our Accoya and Tricoya timber repairs: if rot comes back in a part we repaired within 20 years, we come back and fix it free. The vacuum glazing has a 15–25-year guarantee.
Is there a minimum order?
Yes, 5 windows.