Sash windows are a key feature of many period properties but, over time, the original frames and fittings can start to wear, leading to draughts and heat loss from your property. In this guide, we provide guidance on the best way to repair and restore old sash windows.

Can you repair old sash windows in a listed property?

Renovating original sash windows will help you keep the original character of your property while reducing draughts and improving your home’s energy efficiency.

The scale of repairs will depend on the damage. Decaying timber, broken sash cords, damaged pulleys and broken glass, will all need replacing. For a high-quality finish, it’s important to hire a professional expert to carry out the work for you, who can ensure your windows are properly insulated and sealed.

If you own a listed building and are looking to upgrade old sash windows, it is worth checking with your local planning authority what you can and can’t do before commencing any works.

Can I replace sash windows with casement windows?

The type of windows your property has will be dictated by the era in which it was built. Georgian, Victorian and Edwardian buildings tend to have either casement or sash windows. You cannot however simply swap out one style for the other. Historical accuracy is vital in a listed property and need to be authentically maintained as much as possible.

If you believe that your property originally had different windows to the ones currently installed it might be possible to revert them back to their original design. However, before starting any work it’s important to check with your local planning authority to ensure authenticity and to maintain the integrity of the building.

What is the best way to draught-proof sash windows in a listed building?

Draught-proofing sash windows in a listed property needs careful consideration in order to retain the historic and architectural character of the building.

Simple fixes include adding draught strips or brush pile strips along the meeting rails and sides of the sashes. These are discreet and can help keep draughts at bay.

However, for a more permanent and long-term solution, it’s worth installing secondary glazing. This involves adding an additional layer of glazing on the interior side of the existing windows, providing an extra barrier against draughts without altering the exterior appearance. 

Mitchell & Dickinson’s advanced secondary glazing product, CosyGlazing, is elegant, effective and unobtrusive. It can provide a second layer to sash windows in period properties, helping you to reduce heat loss and improve energy efficiency.

Can you add secondary glazing to a sash window in a listed building?

Yes, you can add secondary glazing to sash windows in a listed building. Secondary glazing involves adding an extra layer behind an existing single glazed window. This is an excellent way to insulate, draught proof and sound proof your windows without losing any of their aesthetic appeal or original features.

High-quality secondary glazing, such as Mitchell & Dickinson’s CosyGlazing, is fixed to your existing glass using high-tech magnetic trips. It is completely unobtrusive, smart and is designed to complement your property.

CosyGlazing fits to every type of window and can reduce heat loss from single glazed windows by up to 70%.