Parts of a sash-window

Sash-window components
a moulded trim that covers the join between the box-frame and the wall. As with other mouldings, this can provide a clue as to the age of the window.
Axle pulley
a pulley wheel set in the pulley stile over which the sash cord runs. The wheel can be cast iron, brass or nylon, the mounting plate is generally cast iron or brass.
Bottom rail
the bottom rail of the bottom sash is deeper than the other rails to allow for the slope of the cill.
Cill or Sill
the base on which the whole box-frame is built. In better quality work it will be made of hardwood (in the best, English oak). It is shaped to shed water.
not a traditional component of a sash window, the draught strips may be incorporated into the staff and parting beads and the bottom and meeting rails. Another type is inserted in a groove in the edge of the sashes.
Fitch catch
a type of catch mounted on the meeting rails to fasten the window
traditionally single glazed, modern sash windows are now made to take sealed double-glazing units. Single glazing may be a requirement when restoring/conserving listed buildings.
a short extension of the sash stiles beyond the meeting rails to strengthen the joint. With modern techniques they are not necessary, but they are a typical and decorative feature of a traditional sash.
Inside lining
the timber that forms the inside face of the sides and head of the box frame. The staff bead is fixed to the inner edge of it.
Meeting rails
the top rail of the bottom sash and the bottom rail of the top sash are called the meeting rails and are generally rebated for weathering and security.
the nosing projects as a ledge from the bottom of the inside of the frame. As sash windows are usually fixed in the inner skin of brickwork, there isn't the depth for a full window board.
Parting bead
separates the two sashes and holds them in place. It is set into a groove in the pulley-stiles and head, and can have draught-proofing incorporated into it
access to the sash weights cut into the pulley stile - more detail
Pulley stile
a side member of the box frame which carries the weight of the sashes and weights, suspeneded over the axle-pulley
Sash bar
also known as a glazing bar or sash-gut, it separates the panes of glass in a sash that has more than one pane
Sash cord
the rope that passes over the axle pulleys used to hang the sashes, counterbalanced by the sah weights
a pair of small handles used for raising the bottom sash, most commonly made from brass
Sash weight
a cast iron or lead weight, a pair of which counterbalance the weight of each sash
a concave moulding used to cover the join between the outside lining and the masonry
Spiral balance
an alternative method of suspending sashes uses a spiral mechanism with a spring that is tensioned to counterbalance the weight of a sash. In a trdaitional box-sash they are set into the edges of the sash stiles, in modern sash windows they are grooved into the frame stiles.
Staff bead
the moulded bead that holds the bottom sash in place is nailed or screwed to the inside lining. A draught-strip can be incorpoated into it.
the side-members of the sash, the moulding from which they are made is called sash-stile
Top rail
the top rail of the top sash is made from sash stile
a closeable vent to allow a small flow of air. Trickle vents are required in new windows to replace the air movement that we call a draught when it comes in around the sashes!
Window board
where you put your plants and ornaments! More usually, a sash window has a nosing rather than a window board.


A pocket is the cover to an opening in the frame. The top is wedged into the pulley-stile and it is secured by a screw at the bottom. In most cases it is fairly simple to remove the screw and prise the bottom of the pocket out, though due to a build of paint-layers it can sometimes be hard to locate the screw.

Detail of a pocket


A mouse is what you use to pull sash-cords through the box sections of sash-window frames. It is basically a weight attached to a piece of string, the main requirement being that it can be threaded over an axle-pulley.

Stages in making a mouse

A traditional way to make a mouse uses a piece of lead flashing, about 50mm x 20mm rolled round the knotted end of a piece of string and hammered so it grips the string. If bent a little it goes through the opening above an axle-pulley easily. As with many old-fashioned techniques there were hazards that people were unaware of, in this case the toxicity of the lead - so don't make one this way!

Anything heavy enough to drop down inside the box section and thin enough to be threaded through will do. I've heard that a short length of bicycle-chain works, but I've not tried it.

Common sizes for sash window timber.

© 2022 Nick Iredale