Will my house value drop if I replace my draughty Victorian sash windows with double glazing?

29 May 2019


I live in a Victorian house where the original sash windows are rotten and the windows themselves are draughty. Some friends have suggested that I replace the windows at the front of the house with double glazing, while others have advised me to hire a specialist sash window company to repair them. I’m worried that replacement windows will devalue the house when I come to sell. Or is being more energy efficient just as important? Any advice?


With period properties, when you come to sell, the original features are often the most eye-catching to potential buyers: the wooden floorboards, the tiled fireplaces and the sash windows. 

Replacement windows could devalue your house if not done properly, but so will rotten windows. I asked Jane Robathan at London estate agency Roy Brooks, and she agreed: “People look for reasons to make lower offers and surveyors look for reasons to down-value homes, so rotten windows will almost certainly impact the value of your home.”  

So what next? Repair or replace? And what with? The decision will no doubt be determined by your budget but here are some things to consider.

Salvage what you’ve got 

There are specialist companies that deal with sash window repairs, fixing rotten sections and improving the fit to address the draughts.You can find sash window installation firms on the HomeOwners Alliance (HOA) website. Simply enter 'Wooden Sash Window Repair' into HOA's Checkatrade search box for a list of local trades. It’s also a good idea to ask friends and neighbours for recommendations. 

Many of these firms will also be able to quote to add double glazing to your sash windows too. This would give you the best of both worlds, allowing you to retain character while improving energy efficiency. 

The Energy Saving Trust found fitting new double glazing could reduce energy bills by up to £110 a year and increase your property's value by up to 10%. So it’s worth looking into.

Replacing old windows with new 

As well as looking at repair and enhancement of your existing windows, get quotes for replacing them.

The average cost of new double glazing is between £400 and £600 per window. So generally it will cost around £2,000 to install four double-glazed windows in a flat and between £4,800 and £7,200 for a standard UK home. 

But prices vary according to size and type of window you choose. Double-glazed sash replacements - as opposed to casement windows, for example - will be more expensive, while wooden replacement sash windows will be more expensive than uPVC.

But think carefully before replacing your original sash windows with uPVC alternatives. It could decrease its appeal and the amount people are willing to pay for your home. The ideal would be to replace original sash windows with like fo like, at least at the front of the house. 

Tips for finding the right windows firm

First, there’s no short cut to finding the right firm to repair or replace your windows. Shop around, get quotes and make sure you are comparing like for like. Look at independent review sites. 

Remember that window repairs and replacement quotes for wooden windows often don’t include the cost of decorating. So you’ll need to get a quote for that too. 

If you’re looking for new double glazed windows, never feel pressured by the old sales tactic of signing up now for new windows before the discounted period ends - there are always discounts. 

Replacement windows will need to be compliant with building regulations. In England and Wales it’s a legal requirement for replacement windows and doors to be registered with your local authority or through a competent person scheme such as FENSA. Failure to do so can cause problems for the future, not least when it comes to selling your home. 

Your new window supplier should arrange compliance giving you a copy of the Building Regulation sign off or a FENSA certificate for your records. There is an overview of Building Regulations you need to take into account with any renovation work on the HOA website.