Casement Windows with Sashes Opening Outwards

If the sashes are hung to solid rebated frames, and open as doors do, the windows are called Casement sashes. If they slide vertically and are balanced by weights or by each other, the window is a Sash and Frame Window.

Styles are the outer uprights. Rails are the main horizontal cross pieces: top rails, meeting rails and bottom rails being distinguished. Bars are any intermediate members, whether vertical or horizontal.

Sashes are from 1 1/2 to 3 inches thick. The inner edge of the outer face is rebated to receive the glass. The inner face is either left square, chamfered or moulded. The size of the rebate varies with the thickness of the sash, its depth being always a little more than one-third this thickness. The width of the rebate varies from a quarter of an inch to half an inch, and the mould is usually sunk the same depth as the rebate. This last fact is of some importance, as it affects the shoulder lines and with hand work it influences the amount of labor in the making of the sashes.

As little materials as possible is used in the sashes, in order that the light shall not be interfered with. In general the styles and top rail are square in section before being rebated and moulded. In casement sashes it is advisable to have the outer styles a little wider than thicknesse specially when they are tongued into the frame. The width of the bottom rail is from 1 1/2-2 times the thickness of the sash. Sash bars, which require rebating and moulding on both sides, should be as narrow as possible in order not to interrupt the light. They are usually from 5/8 of an inch to 1 1/4 inches wide.

Joints of sashes The sashes are framed together by means of the Mortise and Tenon joint. Hardwood cross-tongues are sometimes inserted to strengthen the joints while thick sashes should have double tenons.

Franking the Sash Bars An alternative to halving in sash bars is to arrange the bar which is subjected to the greater stress –as for example, the vertical bars in sliding and horizontal in hinged should be continuous; this continuous bar is mortised to receive the other, which is scribed i.e. cut to fit the first and on which the short tenons are left. This is called franking the sash bars.

Casement windows may be hinged to open inward or outwards and may have one sash or folding sashes.They are hung with butt hinges to solid rebated frames which consist of jambs, head and sill.The head and sill run through and are mortised near the ends to receive tenons formed on the ends of the jambs.The upper surface of sill is weathered to throw off rain water. For casements that reach the floor, sashes require an extra depth of bottom rail and are called French Casements.

An essential feature of all sashes is a small groove or throating on the under edge of the bottom rail which prevents water from getting through. The groove in the rebate of the sill is provided to collect any water that may drive through the joint. This water escapes from the hole bored in the center of the sill. When casement sashes are hung after the manner of folding doors, the vertical joint between the meeting styles is rebated. Hook joint used for this purpose is the better one.

The Casement Windows with sashes opening outwards are more easily made waterproof than inward opening sashes. The chief objections to their adoption are that they are not easily accessible for cleaning the outside especially in upper rooms and that they are liable, when left open to be damaged by high winds and to let in rain during a storm. The sashes can be hung flushed with one face of the frame or fit in the thickness of the frame. The sill shows to be double sunk i.e. to have the upper surface upon which the bottom rail of the sash fits- rebated with two slopes (weatherings).