Period character guide: Windows

Repairing the windows of my house brought me close to the artisans who had carefully fashioned them in the twilight of the Victorian age. As I lifted out the sashes I came across pencilled notes and marks on the unpainted edges and could well imagine white aproned joiners sanding the timber, pulling sash cords through the pulleys and adjusting the window catches just as I was doing.

The history of the window is linked closely to the development of glass. As it became possible to make larger panes, so windows became bigger and fewer divisions between panes were needed. In early timber framed houses the windows were integral to the structure with the wooden mullions simply slotted into the horizontal timbers.

From medieval times, fixed casements – with a frame of timber or iron within which glass was fitted – were known as ‘fixed lights’. To allow the window to open, the casements were hinged on one side but, by the 1720s, casements were being described as ‘common windows’ since the sliding sash had become fashionable. Their first use is believed to have been at the Palace of Whitehall in London, around 1670. Most sashes slide vertically and are suspended on cords and counterbalanced by weights contained in the frame.

Windows were originally set flush with the building’s facade, but after the Great Fire of London in 1666, the dangers posed by exposed woodwork were addressed and it became mandatory for the the sash box to be recessed behind brickwork. Wide glazing bars were a feature of early windows and as the 18th century progressed the glazing bars became thinner and more delicate.

Early metal windows were made of wrought iron but, from the mid 18th century, cast iron was also used. Steel windows started to appear in the second half of the 19th century with Crittall being the main manufacturer.

Window making today
Founded in 1994, The Sash Window Workshop is a family company, based in Berkshire, specialising in the manufacture and repair of traditional timber windows. Managing director Richard Dollar explained to me that the most critical stage in creating a new window is the on site measuring as no two windows are alike and details such as the glazing bars and proportions must be exactly right.

In the workshop, the first stage is to select timber for the particular size and shape of window required and from the site survey a cutting list is prepared. Richard told me that the company has a range of standard moulding profiles but special patterns can be cut exactly to match existing work.

The Sash Window Workshop now uses Accoya, a sustainable softwood, for 80% of its windows because of its strength and durability. Once the timber has been cut and machined the ‘kit’ of component parts is taken into the joinery shop.

Richard emphasised that each window is made by an individual joiner, who begins by setting out the timber and marking out the joints. A traditional mortice and tenon construction is used with the joints wedged and glued. Once all the elements of the window have been fitted together the timber is sanded down before being taken to the paint shop where it is primed. A further undercoat and a top coat are applied with the wood sanded down between each coat.

Next, the window goes to the glass shop where the glass is fitted. One of the most important aspects of sash windows is that they must be perfectly counterbalanced. To achieve this, the windows at The Sash Window Workshop are weighed so exactly the right amount of lead can be used to create the counterbalance weights. The weights and sash cords from which they hang are installed once the window has been fitted.

ABOVE (clockwise from top left): At The Sash Window Workshop timber is selected for the size and shape of the window; The joiner sets out the timber and marks the joints; A mortice and tenon construction is used with the joints wedged and glued; Every element is carefully fitted together and finished; The windows are sanded down prior to going to the paint shop.

Repairing and replacing
The importance of retaining original windows cannot be overstated. They form the face and define the character of our homes, so when they are altered or replaced inappropriately – they can ruin the look of an entire street – with the result that modern replacement windows are often cited as a reason for buyers being put off a property.

Timber windows have a very long life if well maintained and repairing a window is cheaper than installing a new one. One of the simplest methods is to fit a metal angle bracket to strengthen the corner of a sash. Although sash windows seem complicated, and often fail because cords are broken, they’re not difficult to overhaul and most of the work can be done from inside.

For more complicated repairs you may need the services of a good joiner who can dismantle the sash or casement, re-glue sections or make new parts. Ensure this is done on a like-for-like basis using matching materials and construction techniques. Try to keep as much original timber as possible and do your utmost to retain original glass – the imperfections and ripples from the manufacturing process make it a sparkling delight.

Metal windows tend to be more difficult to repair than wooden ones. Problems range from excessive paint build-up or rust to distortion and failed hinges and fittings, but specialist metal window companies, or even a local blacksmith, should be able to help you with repairs.

Thermal efficiency
Windows that rattle and let in draughts may be wedged and sashes can be drawn tighter with a cam action fastener. Many of the companies that specialise in overhauling and repairing windows will also draughtproof them. With sash windows this is done by installing inconspicuous ‘brush’ strips to the top edge, meeting rails and parting beads.

For energy saving reasons it may be tempting to fit double-glazing units into old windows, but these often don’t fit within the rebates of the frame, have a negative impact on the window’s appearance and add extra weight – a particular problem with sashes. An alternative option is secondary glazing with the latest systems, such as Storm’s, using lift out magnetic panels that may be removed in the summer months.

ABOVE (left-right): The windows at The Sash Window Workshop are spray painted; the windows are left to dry between coats; in the glass shop the glass is chosen and fitted
BELOW (l-r): Georgian windows in Thaxted, Essex; An early Georgian sash window with shutters in Spitalfields, London.

Words for word: A glossary of window terms
Glazing Bars: The bars dividing and holding the panes of glass in a window. HORN The extension below the vertical stile of a sash window that strengthens the joint and may be shaped to provide decoration.
Meeting Rails: The horizontal upper and lower rails of a sash window which meet when the window is closed and upon which the catch is fitted.
Mullion: The timber or stone vertical member between the ‘lights’ of a window.
Parting Bead: A thin strip of wood fixed vertically within the frame of a sash window to separate the upper sash from the lower sash as they slide up and down.
Yorkshire Sash: The simplest form of sash window where the sashes slide horizontally instead of vertically.

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WORDS ROGER HUNT PHOTOGRAPHS ROGER HUNT; THE SASH WINDOW WORKSHOP; SYMM
Featured in the August 2010 issue of Period Living