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Sash windows are classic windows that have defined the look of traditional and royal English homes over the centuries. It is conservatively estimated that there are around forty million sash windows installed all across the British Isles. But sadly, most of them are not in working condition, even though the underlying wooden construction is not significantly in need of repair. The common issues that plague such sash windows are sash cords that are broken or rotten wood or pulleys that are rusted. These can easily be remedied by getting a qualified restoration professional to come and have a look at the sash windows to suggest the appropriate repairs to bring the window back to working condition.

You might also want to check out: The benefits of restoring your sash windows

Sash window components

In order for us to understand the complex job of restoring sash windows to their original condition, we need to understand the components of the sash window and their functions first.


A sash window is a window that is comprised of two frames which have the capability to slide over each other in the vertical direction – thus helping an increase in air circulation. This design is an old English design that was perfected in the seventeenth century – adding an aesthetic value to old buildings that have historical appeal up to the present age. Basically, the sash is the frame that holds the glass panels in a window making it as a single component. The glass is movable because of the sash, and this movement can happen independent of the frame.

Lights and glazing bars

The individual panels of glass in the window are known as lights, and these lights are held together by a matrix of bars known as glazing bars. Traditional sash windows are comprised of a couple of sashes which are held together and put on a vertical track balanced together with weights. Sash windows are arranged in a double-hung configuration which gives them the freedom to move in two directions, adjusting for the airflow.

Sash cord

Coming to the sash cord, this cord balances the weights that are contained in the hollow part of the wooden track and it is made of a cotton rope that has been waxed along with a core made of polyester fibre. The main benefits of this cord are that it is very strong, cannot be stretched that easily, and also very easy to clean up. At the top of the casing, there is a pulley where this cord rests – balanced by the weights. These help in opening the sashes out, easily and safely.

Other important parts of the sash window include the sash bars, the pulley, the glazing, meeting rails, sash lifts and so on.

Sash window restoration

Restoring a sash window requires careful attention to detail and availability of original parts to bring it back to the style of the old era. Acquiring olden sash window parts will obviously cost a lot of money as these designs are not as commonly bought in the market.

Estimating costs

For a quick refurbishing job for the sash window, where there are only a few problems – you might end up spending around 2000 pounds to get the window back to its original glory. A reconditioning job for a damaged sash will run you up to 250 pounds for each sash that is to be reconditioned. If you are looking to replace the sash completely, it will run you up to 1200 pounds, or if you are looking to add double glazing to the sash windows, it will end up costing around 500 pounds per sash. These are pretty high prices, but they are worth it, especially as it will end up bringing the value of the sash window up – and mind you, they are valuable. Getting sash windows updated to the modern design principles is not very difficult – but requires a generous budget, to begin with.

Purchasing sash window parts

A window is the most important part of a building, as it serves as the eyes of the building. When looking at an old building, the first thing that most people tend to notice are the windows, and so it is imperative that the windows are kept in good condition. There are many suppliers that offer authentic sash window parts, for restoration purposes, which can easily be procured for all types of sash window restoration work.

There are a lot of sash window components available for purchase on the market, parts like the sashes, rails, bars, stiles etc., which are manufactured from fine wood are available on the market. Procuring such parts for restoration will help the sash windows look authentic to the period that they were first made in. There are sills available as well, which are generally made from oakwood, which is known for its durable and strong nature. Metal components like the weights and the train can also be procured relatively easily from the market. There are many brass-made components that are available for sale.

Restoring sills and rails

Sills and rails are some of the most common components that fail frequently on a sash window. It is pretty easy to replace the sill, but it is tricky at the same time – meaning that it is not very easy to get rid of the old sill, and it is very easy to cause damage to the wooden substructure in the event of any failure with the removal process.

Installing double glazing

Double glazing is another process that brings sash windows back to their original form. In double glazing, another layer is added to the already existing glass layer of the sash window. With double glazing, the energy efficiency of the sash window will highly be improved.

Before a repair word is carried out on a sash window, it is firstly important to find out the complete factors that led to the present state of the sash window and to establish the guilty party before committing to any repairs. With older sash windows, the wood used in it is very rare, and so owners would really try to save as much of the wood as possible, so as to increase the durability of the new windows.

Pieter Boyce - Wooden Window and door specialist

Pieter Boyce
Wooden Window and Door Specialist

This article was written on behalf of Fortis & Hooke by Pieter Boyce. Pieter has an intense passion for English Architectural history and has been specialising in the conservation of original wooden windows and doors for decades. His exceptional knowledge of timber windows and doors, both listed or non-listed, is attributed to his hands-on approach to learning all aspects of the complete restoration of original features as well as having personally surveyed thousands of items throughout his long tenure as a head surveyor for one of the largest window and door restoration companies in the UK. He now runs a boutique wooden window and door consultancy and fervently champions the retention of original windows and doors. To learn more of Pieter’s services, visit his website at www.boultonboyce.co.uk.

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