Glossary of Sash Window Terms
We have created this helpful Glossary of Sash Window Terms.
Hopefully it will help you to understand just exactly what our surveyors are saying!
Add Weights – small metal weights used to build up a Counterweight to correctly counterbalance a sliding Sash. Also known as make weights.
Bead – a woodworking term for a strip of wood with a moulded (often rounded) face. Used either decoratively or to reinforce the point where two straight edges meet. Collectively called beading.
Bottom Rail – this is the Rail that forms the bottom of the Lower Sash.
Box or Case – the Outer & Inner Lining, Cheeks, Box Head and Box Lining together form the sash box (or case), the framework that contains and supports the Sashes.
Box Head – this rests on top of the two Cheek uprights and forms the upper surface of the window Box. The top of the Upper Sash rests against this when it is closed.
Box Lining – a timber Outer Lining to either side of the window, between the stone surround and the window frame. This helps keep masonry dust out of the window frame and offers extra draught prevention.
Cheek – grooved vertical wooden sections either side of the window frame. They stand between the Sill and the top of the sash window Box and provide the Running Surfaces for the Sashes to slide against.
The cheeks have Pulleys through which the counterweighted sash Cords pass.
Cord – a corded rope used to connect a sliding Sash to a Counterweight. Each sash will be attached to cords on both sides of the window frame. Usually made of thick braided cotton. Sash cord comes in different gauges of thickness to suit the weight of the sash it needs to support.
Cord Plug – a metal ring that holds the Cord knot in place, inside the sash Box.
Counterweight – a metal weight used to counterbalance the weight of a Sash and hold it in position at any height. A sash will have counterweights on either side, concealed in a Cavity and connected to the sash via Cords.
The weights are typically made from steel, iron or lead. Where space is an issue, lead weights may be the most appropriate, being denser for their size than other metals.
An alternative to traditional weights is a Spiral Balance.
When a sash needs Rebalancing, Add Weights may be used to adjust the counterweight.
Drifting – a Sash that isn’t correctly counterbalanced and won’t stay in place is said to drift. This causes the sash to move of its own accord, drifting open or closed, or slamming shut suddenly.
A drifting sash needs to be properly Rebalanced to restore the correct operation of the window.
Drip Groove – a narrow channel cut into the underside of an exterior window sill. Its purpose is to stop rainwater flowing back underneath the Sill where it can rot the sill or damage the joint with the outside wall.
Exterior Sill – typically a hardwood beam that acts as the lower surface of a Sash Window. In some cases this sill may be stone rather than timber. This is what the Lower Sash rests on when it is closed. The exterior sill is sloped to allow rainwater to run off and will include a Drip Groove.
Fastener – a security lock that latches the bottom of the Upper Sash to the top of the Lower Sash when both sashes are closed.
Horns – where the vertical Stiles of a Sash extend beyond the height of the sash frame, the extra sections are called horns. Often ornately sculpted. A horned Upper Sash would have horns at the bottom, whilst a horned Lower Sash would have the horns at the top. These provide extra strength to the sash frames.
Inner Sill – this is a wooden sill on the inside of the window, jutting out a short way into the room.
Inner & Outer Lining – these are timber side pieces that help form the inside and outside Box of the Sash Window frame.
Lite – an individual pane of glass in a window frame, often held by Muntin bars.
Lower Sash – the bottom sliding window frame of a Sash Window. The lower Sash is the one nearest the inside of the window (building interior).
Meeting Rail – the bottom horizontal Rail of the Upper Sash and the top horizontal Rail of the Lower Sash are called the meeting rails, since they meet in the middle of a closed Sash Window. Also known as lock rails.
Muntin – a strip of wood that divides a window horizontally or vertically into smaller panes of glass (or Lites). Also known as muntin bars, glazing bars or sash bars. Georgian sash windows typically have ‘six over six’ panes, meaning each Sash has six individual panes of glass separated by muntin bars.
Parting Beads – long wooden strips that sit in a grooved channel in the Cheek and Box Head to separate the Lower and Upper Sashes so that they move freely and independently. These can be fitted with Weatherpile Carriers for reducing draughts.
Pocket – within each Cheek is a removable cut-out section called a pocket, these allow access to the sash Weights behind. The pocket is concealed by a wooden panel called a pocket cover.
Pulley – a metal or plastic roller through which the weighted sash Cord passes as the Sashes are opened or closed.
Rail – a horizontal wooden piece that forms the top and bottom parts of a Sash frame.
Rebalancing – with painting and redecorating, over time a Sash can get heavier, causing it to become unbalanced and Drift, as its Counterweights no longer hold it correctly in place. When this happens the sash needs to be reweighed and rebalanced, with adjustments made to the counterweights, so that the sash operates properly again.
Re-cord – when a Cord holding up a Sash breaks or shows signs of deterioration and age, it should be replaced and the sash Rebalanced. It is good practise to replace sash cords as a pair.
Router – a specialised carpentry power tool for cutting grooves or channels into wood. Pronounced “raow-ter”.
Routing – the term for using a Router to cut a precisely sized channel into a piece of wood.
Running Surfaces – the inner faces of the sash Box that the Sashes make contact with.
Sash – a sliding window frame, made from timber Rails and Stiles, containing panes of glass (or Lites). The sash frame is held within an outer wooden Box, along with a set of Cord ropes, Pulleys and Counterweights which support the heavy frame and enable it to move up and down.
Typically a Sash Window will consist of a pair of sashes: the Lower Sash and Upper Sash.
Also known as a sliding sash.
Sash Window – a traditional timber frame window that consists of moveable Sashes. Typical in period houses from the Georgian (including Regency), Victorian and Edwardian eras.
Also known as a box sash window, as well as a single or double hung sash window, depending on whether one or both of the sashes can be moved. The individual sashes are contained together within a Box or case.
Side Rail – a structural timber section that forms one vertical side of a Sash. Despite the name this isn’t actually a Rail, it is a Stile.
Sill – a ledge or shelf that forms the lowest part of a window frame. Normally this term refers to the Exterior Sill but may also include an Inner Sill.
In the 1800s this was spelled “cill” and is sometimes still used in this way by the construction profession.
Spiral Balance – a tube containing a stainless steel rod and tension springs. This device replaces the traditional Counterweight, Cord and Pulley arrangement, freeing up room in the window Box. Also known as a Spring Balance.
Staff Beads – moulded wooden strips that hold the Lower Sash in place and prevent it from falling into the room. These can be fitted with Weatherpile Carriers for reducing draughts.
Stile – a vertical timber section that forms one side of a Sash frame. These side pieces are also somewhat confusingly named Side Rails.
Top Rail – This is the horizontal Rail that forms the top of the Upper Sash.
Upper Sash – the topmost sliding window frame of a Sash Window. The upper Sash is the one nearest the outside of the window (building exterior).
Weatherpile – a flexible fin or brush shaped strip designed to seal gaps and keep out draughts, whilst allowing free movement of the sashes.
Weatherstrip – a narrow plastic grooved channel into which a draught proofing Weatherpile can be fitted. Also known as a weatherpile carrier.
These can be fitted into the sash Rails, Parting and Staff Beads.
Whilst cheap stick-on adhesive weatherstrips are available, the long-lasting solution is to use a Router to create a permanent groove in the timber frame into which the weatherstrip sits.
Weight Cavity – The concealed space on each side of the window frame where the Counterweights hang. Also known as the weight pocket.