Sash Windows & Doors – Replace or Renovate?

Sash windows and doors are beautiful to look at. They really add character, and with a period property can add value.

If you have sash windows that are a bit worse for wear this article is for you. Here we are going to give you the information you need to decide whether sash window renovation or replacement is the best option.


If you live in a listed building, the decision is more or less made for you. English Heritage recommends repair.

However, provided you can prove the windows are beyond economic repair you can replace them. The new windows will have to look like the originals and approval from your councils Planning Department will need to be obtained prior to carrying out the work.

Repair is normally cheaper

For non-listed buildings, replacement is an option, but repair is normally the cheapest option. However, that said, every window is going to be different. How much it will cost to get your sash windows looking good and operating properly depends on the state of each window.

Mechanism Issues

The mechanism that opens and closes sash windows always wears. If your window is malfunctioning, you may need replacement cords or weights. Sometimes the weighting mechanism just needs adjustment or pulleys need servicing.

If your problems are only with the mechanism, 99% of the time renovation is the best answer. It is almost always far cheaper than replacing the window.

Frame Issues

Frame issues are different. If you just need a new sill, bottom rail, or a single sash box replaced renovation is usually more economical. When repairing windows a lot will depend on the materials used. For longer lasting results, windows should be repaired with resin as opposed to the standard wood fillers many will use and use good quality paints. On the other hand if most of the frame has gone and you have mechanism problems a new window is usually best.

You will be required to fit double glazed windows when replacing existing single glazed windows to comply with current Building Regulations and the work is notifiable to your local Building Control Department unless your fitter is FENSA registered and can self certify the work.

Other factors to consider

When costing out the options there are a few other things you need to consider.

If you own a period property replacing the windows with modern ones may adversely affect its value. This needs to be factored in.

You also need to consider how much money you could save on heating if you were to replace old-fashioned single glazed sash windows with double glazed ones.

The best approach is to call in the experts and get quotes for both repair and renovation. Armed with these quotes you can make an informed decision. It is also important to use a Fensa registered fitter when fitting new double glazed windows who will provide a certificate, which will be required when selling your house.

Other things to bear in mind when replacing a window: some making good to the walls externally and internally might be required, so you’ll need to allow for this. New timber windows will need to be painted following the fitting, so you will need to hire a painter and decorator for this job.

Replacing windows is never an easy decision. We would always recommend refurbishing them and upgrading their thermal performance with weather proofing strips and other means if it is economically viable.

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"Tibor did some extensive renovation work to the exterior and interior of our property a few years ago. The work is immaculate, he is meticulous and thorough, and a perfectionist, and will always get to the root of the problem, before doing any surface decoration. I would highly recommend his services."

Paul and Sara Jane

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