At the front of our house we have 5 beautiful Georgian sash windows. They were probably installed when the house was first built in the 1780s and I’m awed by the fact that wood from trees grown 250 years ago is still perfectly functional today. I wouldn’t change them for the world but what I would change is the distinct chill I feel when sitting near them and the eerie rattling sound they make on a blustery night.  The solution to both these problems, I discovered, is to have them professionally draught-proofed.

The technique involves removing the sashes from their frames, cutting a groove around each one using a mechanical router and then sliding a draught excluding brush seal into the groove so that it becomes an integral part of the window.

Once finished, the sashes should fit snuggly within their frames and eliminate about 90% of draughts and all disturbing rattling noises. It’s a specialist job and each sash window takes a day to complete. Depending on the size of your windows, it costs around £650 per window so it’s not a cheap exercise but it’s a quarter of the price of having new windows made, it preserves historic fabric and will improve the comfort level of your house no end. A small consolation to the price is that, as an energy efficiency improvement, the work is subject to 5% rather than 20% VAT.

There are a whole series of companies that do this work, with Ventrolla being the largest. Others around the South East include Envirosash, the Oxford Sash Window Company and Simply Sash Windows – the last two of which I have used and found to be excellent.

A few things to watch out for:

• Ask questions about the best type of seals for your windows – rubber compression seals are usually best for hinged (casement) windows whilst brush seals are best for sash windows. Paying more for better quality seals is sensible because it’s a small element of the overall cost.
• Ensure any planed edges of your windows are primed by the draughtproofing company before they are rehinged otherwise water will get into them and make them swell.
• Fitting sturdy, twist-action sash fasteners is worth it – they hold the sashes tightly together and create an airtight seal.
• When painting the windows avoid getting paint on the brush seals.