Sash windows: repair or replace?

Follow expert advice to decide whether to fix your sash windows or replace them with a new design.

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Decide which is the best option for your home with this up-to-date expert advice. 

Image above: Combining the traditional style of vertical sliding sash windows with the performance of modern uPVC casement windows, the VS frame from Quickslide is an affordable way to improve your home’s energy efficiency while still retaining its period character. Prices start from £230.40 for a white sliding sash, (H)90x(W)60cm. 

Can all windows be fixed?

‘It depends on their overall condition, but some old timber sash windows can often look in a worse state than they actually are. Once the paint starts to flake off, it instantly makes windows appear in poor condition,’ explains Dave Greaves, managing director of period window specialist Ventrolla. ‘If there are areas of rot, these can be cut out and replaced with new timber, and even rotten sills can be replaced. It’s a little like cutting out the bruised area of an apple – part of the window might be rotten, but the rest could be perfectly fine.’

What are the most common repairs?

Typical repairs include replacing the sash cords, installing new parting and staff beads, servicing the pulleys, replacing any damaged glazing, repairing or replacing any damaged timber and adding draughtproofing. ‘Ventrolla can install a draughtproof strip around the perimeter of both the top and bottom sashes as well as across the meeting rail, improving the energy performance of the window by around 30 per cent,’ explains Dave Greaves.

How is the work done?

Most repairs on sash windows can be carried out in situ. ‘As the renovation work can be done from inside the house, there’s no need for expensive scaffolding on the exterior of your home,’ adds Dave Greaves. ‘It would typically take around a day to repair an average-sized window measuring one metre wide and 1.5 metres high.’

When is it better to replace for new windows?

If the windows are in a particularly poor condition and your key priorities for upgrading are to improve thermal efficiency or reduce external noise, then a new design could be a better long-term solution. If you want to maintain your home’s character, however, it’s important to replace like for like. ‘Traditional timber windows that replicate the original aesthetic are a key feature for potential buyers,’ says Richard Dollar, managing director of The Sash Window Workshop. ‘On period houses in London, for example, where uPVC windows have been installed, it can actually decrease the property’s value.’

Totali Sash Windows

totali sash windows

Ideal for period, modern or farm style homes; Totali sash windows are fully draught sealed to eliminate the draughts and rattles so often associated with original sliding sash windows. They are also designed for the specialist needs of conservation areas throughout the UK. Discover the beauty of timber with low maintenance timber sash windows, hand finished to your specification.


New timber sash windows will also improve your home’s overall thermal performance, says Colin Virtue, technical development manager at timber window and door specialist Allan Brothers. ‘Opting for new designs can vastly improve energy efficiency thanks to the double- glazing, compared to original sash windows, which may only be single- glazed. Our sash window designs can achieve a U-value of 1.5W/m2K. New designs are also a great investment – maintained properly you can expect them to last for 80 years.’