Sash windows are a must-have for many self-builders wishing to give their homes a traditional appearance, but it’s not always easy to get the style right. This guide not only explains how sash windows work, but how to make sure they work for you.
10 Things To Consider Before Buying Sash Windows
1 Sash windows are an inherent part of British architectural history: they were introduced to England in the late 17th century and remained a sought-after fashion item for over two centuries. Any styled property from this era would be lacking without them, and this is why it’s so important if you are renovating a Georgian, Regency or Victorian property, or building a new house in one of these styles, that you include them.
2 The word ‘sash’ simply refers to a single frame for glazing. A traditional ‘sliding sash’ window is usually made up of two sashes that slide up and down, one in front, and one behind, in vertical grooves, counterbalanced by lead weights on cords — though in many modern windows, the weights have been replaced with springs. Sliding sash windows can be opened at the top or bottom, or both, depending on the design, and though traditionally they have no outward swing, many modern designs tilt in and out for easy cleaning.
3 Sashes traditionally consist of a number of small panes, or ‘lights’ that are held together by glazing bars to create a larger glazed area. This is because glass advancements at the time didn’t allow for very large expanses of clear glazing. The number of panes depended on the era: ‘six over six’ is quintessentially Georgian, though larger ‘eight over eight’ windows were also common. In Victorian times, ‘two over two’ reigned supreme, but throughout the whole period, many other configurations were seen, as well as the inclusion of sidelights.
4 Sash windows for period properties must be chosen carefully to ensure you get the right period, as there were several developments and style changes in sash windows over the years. Different designs included the Venetian, which consisted of a central sliding sash with two fixed side panes, and the Queen Anne Revival style, where there were several panes in the upper sash, but just one or two in the lower sash. In the Regency and Gothic revival periods, sashes were often arched instead of rectangular; and in some regions it was always popular to have horizontally sliding sashes.
5 All too often, renovators make the mistake of removing original period timber sashes and replacing them with new models, when if they had simply been restored to their former glory, they would have been perfect. Where possible, existing sashes should always be repaired and waterproofed, but if the windows are beyond repair, or there aren’t any left in place, there are many companies who will manufacture authentic replacements.
6 Genuine timber sash windows are likely to be the first and only choice for traditionalists and those living in either a Conservation Area or a listed building. You simply cannot achieve the same effect with plastic. Wood is very durable and an excellent insulator, and if taken care of properly, a timber frame can last for centuries. A common misconception is that timber windows are highmaintenance, but with the use of modern finishes – available in almost any paint colour or stain imaginable – they really don’t require a lot of upkeep, just some periodic maintenance and to be examined once a year for cracked, flaky paintwork and decay.
7 PVCu is often used as a substitute for painted wood. Though most commonly seen in white, it comes in a wide range of colours and finishes, including a photo-effect wood finish. It is lowmaintenance and energy efficient, though it can’t be recycled. When bought off-the-shelf, PVCu is usually far cheaper than timber, which can cost as much as 40% more. Many conservationists are opposed to plastic windows, but the better quality models can be attractive and hard-wearing, though they are difficult to repair.
8 It is becoming popular for sash windows to be composite in their construction, with timber on the interior, but clad with aluminium on the exterior. This ensures they retain the classic look of wood on the inside, but outside are extremely low-maintenance and are able to withstand all weathers.
9 Traditionally, sash windows were single glazed with fine glazing bars to hold the panes in place; but modern building regulations make it near impossible to have single glazed windows on a new house, so you may have to sacrifice true authenticity. It is, however, possible to install single glazed windows on many renovations.
10 Dividing up small units of double glazing with thick bars tends to look clumsy, but there are ways to effectively recreate fine glazing bars. The best way is to bond mock bars onto either side of a single double glazed unit. You could also incorporate spacer bars between the glass sheets, at a higher cost, to add to the effect.
How Sash Windows Work
1. Top Rail: The top horizontal framing member of a sash. Rabbeted (SEE GLAZING BAR) on the outside.
2. Box Frame: Sometimes referred to as a ‘jamb’, the main box frame consists of three TIMBER LININGS.
3. Sash Cord: Runs over the PULLEY WHEEL and holds the WEIGHTS. It can be bought in rolls when it needs replacing (the waxed type is best). Chains are an alternative.
4. Weight Pocket: The WEIGHTS hang in the pockets created by the TIMBER LININGS on each side of the window. Insulation can be retrofitted in the pockets of older windows.
5. Parting Bead: A long, narrow vertical seal that fits in the BOX FRAME to form separate channels for the upper and lower sashes to run in, and holds the top sash in place. Newer beads often have built-in draught seals. On the upper sash, the bead is fitted facing inwards; on the lower sash it faces outwards. The fit should be snug to prevent heat loss.
6.Staff Bead: A moulded piece of timber made up of four sections, nailed all around the BOX FRAME, which aids airtightness and also holds the bottom sash in place. The staff bead is removable, but rarely salvageable, for the maintenance of the sashes.
7. Meeting Rails: The horizontal framing members which meet the two sashes together in the middle. Their adjoining faces are bevelled so they close together tightly.
8. Stile: Vertical side framing member of a sash — there is one each side.
9. Apron: A decorative panel or cladding beneath the window.
10. Cill: A horizontal board fitted internally at the base of the sashes. Shaped so that water flows away outside.
11. Bottom Rail: The bottom horizontal framing member of a sash.
12. Weight: A pair of lead weights hung on the SASH CORD counterbalance each sliding sash. The sash and weights must weigh the same.
13. Wag Tail: A strip of timber inside the BOX FRAME that separates the WEIGHTS. Also known as a ‘parting slip’.
14. Timber Linings: The sections that form the casings of the BOX FRAME – which must be hollow to house the WEIGHTS – are made in three parts: the ‘outer’, ‘inner’ and ‘pulley’ linings.
15. Pulley Wheel: A pulley mortised into the top of the PULLEY LINING; the SASH CORD passes over it to counterbalance the WEIGHTS. Cheaper pulleys have plain axles; better quality ones are made with roller or ball bearings.
16. Glazing Bar: A vertical or horizontal framing member that divides the panes within the STILES and RAILS. Each is rabbeted – a cut which forms a groove – to hold the single-paned glazing. The quintessential Georgian sash window has ‘six over six’ panes, but other configurations were seen over time.
17. Soffit Lining: The window’s head is made up of the main inner and outer TIMBER LININGS as well as a separate soffit lining; glued triangular blocks provide strength.
NB: A ‘sash’ is a single glazing frame. The full name of a sash window is a ‘vertical double-hung box-framed sliding sash window’.