Replace a sash window when the frame or sill has rotted through, the box frame has distorted, or you want better glazing than the old sashes can carry. If the timber is sound and the trouble is sticking, rattling or draughts, repair may be enough. A survey of each window settles it, so not every window has to go.
Signs a sash window needs replacing
Most sash windows we are asked about are not beyond saving, but some are. These are the signs that point towards replacement rather than repair:
- Soft, crumbling timber at the sill, the bottom rail of the lower sash or the foot of the box frame.
- A frame that has moved out of square, so the sashes bind whatever is done to the cords or beads.
- Earlier replacements that lost the original look, such as heavy frames or glazing bars that do not match the house.
- Single glazing you want to upgrade where the old sashes are too slight to take a thicker sealed unit.
When repair or refurbishment may be enough
Sticking sashes or tired paint do not on their own mean the whole window needs replacing. A broken cord, a swollen bead or worn draught-proofing are repairs, not reasons for new windows. If the box frame and sill are sound, ask about repair first; it keeps original timber and glass in the house.
| Repair or refurbish | Replace | |
|---|---|---|
| Best when | The frame and sill are sound | Rot or distortion has gone into the frame |
| Typical fixes | Cords, beads, draught-proofing, paint | A new made-to-measure window |
| Glazing | Usually stays as it is | Double, triple, Heritage Slimlite or vacuum |
| Look | Original timber kept | Proportions and glazing bars recorded and matched |
What a new timber sash window can include
A replacement sash should look like it belongs to the house. At survey we record the opening size, the sash proportions, the glazing-bar layout and the mouldings, then make the window to measure. You choose how it slides: traditional cords and weights, or a spring balance.
All our timber windows are available with double or triple glazing, and our sash windows also come with Heritage Slimlite slim double glazing or vacuum glazing. Slimlite and vacuum units are slim enough to sit in a traditional-looking sash, which matters on period homes and in conservation areas. Our sash windows also carry an extra security feature against burglary. See the options on our timber sash windows page, or compare with heritage slimline windows.
Do you need planning permission to replace sash windows?
For a house, new windows of a similar appearance to the originals usually do not need planning permission, according to the Planning Portal. There are exceptions that matter in and around Cambridge:
- A council can make an Article 4 Direction that removes those permitted development rights.
- A listed building needs listed building consent for any significant works, inside or out.
- Houses in a conservation area can carry extra restrictions. Greater Cambridge publishes its conservation areas and their appraisals.
- Leaseholders may need permission from their landlord or management company first.
Replacement windows also have to meet the energy rules in Approved Document L of the Building Regulations. Schnauber is FENSA registered, so the work can be certified as compliant without a separate building control application.
How long does it take to fit a sash window?
One sash window takes our team about a day to install, including the architraves and finishing. We confirm the timings for your house at the free survey.
What does sash window replacement cost?
The price depends on the size and number of windows, the glazing, cords and weights or spring balances, the glazing-bar pattern and the finish. That is why we quote after a free survey: you get a detailed, no-obligation quotation for your windows rather than a guess from a price list.
Sash windows in Cambridge and nearby
Our head office is on Mill Road in Cambridge, a city full of Victorian and Edwardian sash windows. We survey homes across Cambridgeshire and beyond, including Cambridge, Ely, Saffron Walden, Royston and Bury St Edmunds. If your windows are on an older house, our guide to windows for period and listed homes and our comparison of sash and casement windows are worth a read too.