What are sash windows? UK costs, how they work, and pros and cons

Independent

20 hours ago

If you are looking to get your windows replaced and you are researching prices from the best window installers, you will probably have noticed that sash windows are costlier than other styles. And if you are wondering what sash windows are, rest assured you're not alone. These traditional windows have a unique design that affects how they work, how much they cost, and how you clean or paint them.
Sash windows, which slide up and down rather than opening outwards, are commonly found on Georgian or Victorian houses and date back to at least the 1670s.
They are often found in conservation areas, which means that they can only be replaced with another sash window in order to maintain the look of the house and comply with local rules.
In this expert guide, we look at why sash windows cost more than regular windows and whether they are worth it, taking in analysis from an expert sash window fitter. But first, let's explain how sash windows work.
What is a sash in a window?
A sash in a window is the frame that holds the glass panes in place. In sash windows, there are usually two sashes that slide vertically past each other within the frame. Each sash can move independently to allow for ventilation.
How do sash windows work?
Sash windows work by using a system of cords and counterweights hidden within the frame. These weights balance the sashes, making them easy to lift and hold in position. Some modern versions use springs instead of weights.
Why do sash windows cost more?
Tom Coles, managing director of Mitchell & Dickinson, a company which makes period homes warmer and restores sash windows, said: 'A sliding sash window has many more components than a casement window. The sashes themselves are carefully positioned so that they run past each other. There's more manufacturing work to do, there's more components, and they need to be set really carefully so that they function perfectly.'
Sash windows usually have two sliding panels, called sashes. Each sash holds a sheet of glass divided by glazing bars to create the look of multiple small panes.
To keep the sashes from moving on their own, they are counterbalanced by weights fitted inside the window frames, connected by ropes.
This slightly more mechanically complex arrangement makes them more expensive to make and to fit. To work well, they need to fit closely in their frames to prevent draughts while still moving freely — engineering that adds further to the cost.
Traditionally, they are made of wood, which creates further challenges, since it is a comparatively expensive building material and it can also expand or contract with temperature changes and damp.
Newer models can be made of uPVC plastic, which is cheaper and does not rot or expand. Aluminium sash windows are also an option but with fewer suppliers and models available.
Aluminium, wood, and uPVC windows can be single, double or triple-glazed.
Another reason for expense is a lack of standardisation. Many Victorian properties will have fairly uniform 4-foot-wide windows. But they were not factory-made and can often vary slightly in size, meaning that each window will require a degree of customisation to make sure it fits, adding to the cost.
Are sash windows draughty?
Older sash windows can become draughty over time if the seals wear out or the timber shrinks. However, many modern sash windows include draught-proofing strips and double glazing to keep homes warm and energy efficient.
How to open sash windows safely
To open a sash window, unlock it first. Then, hold the bottom sash on each side and gently lift it upwards. For ventilation, you can also lower the top sash slightly while raising the bottom sash, which creates airflow around the room.
How to clean and paint sash windows
To clean sash windows, tilt or lift the sashes to access both sides of the glass. Use a gentle cleaner and a soft cloth to avoid damaging the frames. If you need to paint them, remove any old flaking paint, sand the surface lightly, and use a specialist wood paint for a lasting finish.
Are sash windows worth it?
In short, sash windows are considered by many to be prettier. However, they are more expensive to make and maintain because they are more complicated and nonstandard compared to a hinged casement window.
Mr Coles said: 'Sash windows are a real piece of Britain's architectural heritage. They were designed so that you could drop the top sash down and pull the bottom sash up slightly, and it creates air flow around the window. It was a clever bit of Victorian and Georgian engineering.'
'They've definitely got their place, and of course they're kind of beautiful to look at and beautiful to operate.'
How much do sash windows cost?
The average cost of replacement of a sash window is £1,300, according to our survey of suppliers, with wood frames costing more and uPVC being cheaper.
In London, you will pay more, with prices ranging from £2,500 to £5,000 per window for wooden frames and double glazing. If you are having multiple windows replaced at once, you can often negotiate a lower price per window because travel and setup costs are reduced.
Repairs can range from £80 to just under £500 to restore the look of the frame, repair the cord, or draught-proof the window, depending on how much work needs to be done.
If you have a row of sash windows and don't insist on opening all of them, then you can save on repairs by sealing some shut.