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From Wood to Stone Lintels: The Evolution of Window Design

Windows are an integral part of building designs, giving the right amount of light and adding to the aesthetics of the building. Over time, the design of windows had changed massively to accommodate new technology and needs. From concrete sills to uPVC, the modern windows we use today are hugely different from those in the past. While many buildings still make use of wooden and stone window headers and sills, the evolution of these has changed hugely throughout the years.


To learn more about window design, keep on reading.

stone window sill

Early stone and timber windows

Beginning in the 16th century, windows were typically made using both stone and timber. Tudor stability and prosperity were reflected in window size. The much larger windows were subdivided into smaller openings and stone and timber windows had horizontal bars. Usually, a wrought-iron frame would be set into the mullions with a smaller opening frame.


It would then be latched shut with an iron catch or held open with an iron stay. It was during the 16th century when glass first started being used in homes. It was very expensive and difficult to make big pieces of glass so the panes were tiny and held together with lead in a criss-cross pattern or ‘lattice’. As glass became more available, windows became even larger. The Italian Renaissance's influence in Europe meant that window design was conforming to classical ideals.

Cross casement windows

During the 17th Century, windows began to conform to more classical ideals, particularly during the accession of the House of Stuart in 1603. This meant that windows became taller and wider, typically divided into four lights by a single mullion and transom often of masonry. Windows at this time were still constructed using timber and were called cross-casement windows. There were a variety of stone windows during this time, mostly made with mullions that were ovolo mouldings.


Timber frames became more fashionable than stone and the mullions and transoms started to be more narrow. You would now find the glazing to be placed flush with the external face of the window. Window frames would now have become less conspicuous while the surface area of glass increased. In 1674, the introduction of crown glass formed a cross-casement window that had larger panes of glass held by timber or iron glazing bars instead of thin small panes in a leaded lattice.


The newly invented sash replaced the cross-casement windows in Britain and many new timber frame buildings adapted to the new fashion. Sash windows were inserted with a skin of brickwork or stone to cover the front of the timber frame. The first type of sash window was the top sash; it was fixed and the bottom sash slid upwards in a groove held open using pegs or metal catches. The ‘double hung’ sliding sash window appeared in the latter half of the 17th century. This is where both the upper and lower sashes hung on cords counter-balanced by hidden weights in a hollow part of the frame called the sash box.

Evolution of the sash window

Later on, we continue to see the evolution of the sash window and over the 18th century, we would see them made from only Baltic Pine. The glass on these windows continued to get thinner while the width of glazing bars slowly got smaller and internal mouldings were of ‘lamb’s tongue’ type. Glazing bars became more slender, typically, made from iron and copper. In the 1770s, we saw the introduction of plate glass which showed an increase in pane size and reduced numbers of glazing bars, however, this could only be afforded by the rich. The standardised window unit was the Georgian ‘six over six’, but at this time there was still a great deal of variation.


By mid-century, the average homeowner would have sash windows as they became less expensive. By the end of the century, they were seen even in the smallest of dwellings. These timber frames were often painted black and even greens and browns were often seen around. Wealthier families would paint them black and embellish them with gold leaf. Throughout this time, sash windows replaced casement windows, although some survived in smaller dwellings. Increasingly, we would have seen timber glazing bars and crown glass.

Larger windows, glazing bars and iron frames

In the 19th century, the size of the windows grew. It was more fashionable and a sign of money to have larger windows that let in lots of light. This meant that window sills were lowered to form access to balconies and were often replaced with French windows. The popularity of narrow-margin lights increased and were often filled with fashionable coloured glass. We would have also seen more glazing bars curved into interlocking gothic-style arches for ‘Venetian’ windows.


Plate glass became increasingly more available which meant that glazing bars would be removed completely. By 1837, glass became much more affordable due to improved methods of manufacturing. By mid-century, most windows had only one central glazing bar or none at all. In the second half of the 19th century, a Gothic revival meant that iron casements and imitation lead quarrel glazing were used to create small diamond or rectangular panes.


There was some experimentation with setting plate glass in iron frames. However, these were mostly used for conservatories, hot houses or industrial buildings. They started to become more popular in estate cottages. Later in the century, we would see two new styles appear;  the ‘Arts & Crafts’ movement of genuine leaded lights set in stone mullions or oak frames and white-painted small pane sash windows. Both of these styles merged and buildings would contain both elements sometimes even in the same window.

Modern windows

Eventually, a new material appeared which would replace timber windows. In the 1980s, property prices began to rise and replacement windows were highly popular by the 1980s. It was during this time that the UK was introduced to uPVC from Germany. It was found that aluminium frames were too cold and caused condensation during the winter, whereas uPVC was considerably warmer.


uPVC windows could open outwards but were glazed externally with inadequate security cockspur window handles. To achieve a Georgian style, leaded designs became popular with white glazing bars across window panes.


Stone lintels, stone window headers and concrete sills have been used since well before the 16th century. The use of stone appeared in the medieval period in grand architecture such as churches. The window frame usually had an arched head and below, the individual lights were supported by decorative tracery with cusped heads.


The arch would have projected from the wall and offered weather protection to the window. Stone lintels have become increasingly popular due to the timeless look they offer. A stone lintel is a common type of lintel and is used where the stone is easily accessible. Precast stone lintels, however, can be manufactured anywhere where a cast stone supplier is available.

Shropshire Brick & Stone UK Ltd - Stone Window Headers & Concrete Sills

At Shropshire Brick & Stone UK Ltd, we offer a range of quality cast stone products including stone lintels, stone window headers and concrete sills. Whatever kind of precast stone product you are looking for, we can help you. Get in touch with the team today to learn more about our services and what we provide. If you want to add beautiful pre cast stone features to your home, Shropshire Brick & Stone has got you covered. Our expert team will be happy to assist you in finding the best quality precast stone products to make your dream home come alive. Call us today on 01743 861111.

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