Sash Windows in a Conservation Area: Everything You Need to Know  

Traditional sash windows are a beautiful feature in older and period properties, but can they keep your home warm and cosy? And will they cost you a fortune? 

Photography courtesy of The Sash Window Workshop

Is it best to go for timber sash windows or uPVC sash windows? Do wooden windows require a lot of maintenance? Are they expensive? And what are the rules if you want to upgrade your windows in a conservation area or listed building?

The Resident asks the experts at The Sash Window Workshop, which specialises in manufacturing and installing high quality, traditional timber windows and doors across London and the south, to answer all these questions and more…

Is it possible to have draft-free, energy efficient sash windows in keeping with a historic building?
Yes, all our timber windows are designed to improve energy efficiency while preserving the character of the property. Our traditional sash windows are bespoke and manufactured by expert craftsmen in our workshops in Berkshire. We work hard to replicate the proportions and designs of historic windows as closely as possible, while incorporating the latest manufacturing techniques so that you can have both authentic sash windows and a cosy, draft-free home.

Are there restrictions when it comes to replacing sash windows in a conservation area or listed building?
If you live in a conservation area or have a listed property, you may require planning permission to replace windows. There is more flexibility in a conservation area, meaning double glazing is likely to be approved, but the rules are tougher when it comes to listed buildings. Single glazing is normally required, meaning many listed building owners opt for secondary glazing for warmth. Double glazing can sometimes be installed, providing it uses a narrow profile (such as our Heritage unit), and planning permission is always required before replacing any windows. At The Sash Window Workshop, we have extensive experience complying with conservation area and listed building requirements, so we can always advise you.

Case study: A Victorian home in East London

How much maintenance do they require?
People tend to assume that uPVC windows last longer, but that isn’tnecessarily correct. While the upfront cost of timber sash windows can be more expensive, well made wooden windows that are properly maintained have a lifespan of around 60 years, compared to the 10-year guarantee you often get with uPVC. Technological advances mean that you can now get low-maintenance timber frame windows that offer improved security, sound insulation and heat retention. We recommend using a timber called Accoya, which requires minimum maintenance and comes with a 50year anti-rot guarantee.  

How do you know if sash windows need replacing or just repairing?
Whether your sash windows need replacing or repairing will depend on their condition. If they are draughty, but otherwise in a good condition, we can draught proof and overhaul your windows. If your sash windows are rotten, they will need replacing. If the window frames are still in a good condition but the moving parts require replacing, we can install new sashes into the existing window frame, so you don’t have to replace the whole window. This can include upgrading your windows to be double glazed if the frame is the right thickness.

Case study: Installing new sashes into existing frames in Islington

Do timber sash windows add value to an older property?
Yes, wooden sash windows can add value to a property, especially in older or period homes where character and original features are attractive to buyers.

Can you have double-glazed sash windows?
Yes, double-glazed sash windows are an ideal choice for those who wish to maintain the look and feel of a period property, while improving energy efficiency. There is no reason to be choosing between period-appropriate wooden windows or the warmth and comfort of double glazing. You can combine double glazing with authentic timber sash windows, giving you the best of both worlds.

What kind of timber do you use? Is it sustainable? 
We use a sustainably sourced timber called Accoya, which is known for its stability and durability, and we are FSC certified. Timber windows are a lot more environmentally friendly than uPVC windows. For every timber window you install instead of a plastic window, you will save approximately 160kgs of carbon dioxide.

What’s the most important thing to look for when choosing a window company?
Look for stamps of approval from official bodies. The Sash Window Workshop is proud to be both FENSA registered (meaning our installations are checked to ensure they comply with building regulations) and a Which? Trusted Trader. Plus, half our orders come from previous customers and recommendations.

More about The Sash Window Workshop
Established in 1994, The Sash Window Workshop manufactures, installs and repairs sash windows, casement windows, French doors, bi-fold doors and front doors. The company has worked on a wide range of properties, from small flats and commercial properties to prestigious buildings including Buckingham Palace and The Admiralty Buildings.

For further information or to obtain a free, no-obligation quote, call The Sash Window Workshop on 01344 868 668, see or download the brochure here