Double Hung Sash and Frame Window

In this class of window, which is by far the most common as it is easily made water proof there are two sashes which slide past each other in vertical grooves and are usually balanced by iron or leaden weights. The frames form cases/boxes in which the weights are suspended (called cased frames) which take the place of the solid rebated jambs of casement windows. Pulley styles, outside and inside linings and back lining together form a box subdivided by a vertical parting slip.

In superior window frames of this kind the pulley styles and linings are tongued and grooved together. The frame must be so constructed that the sashes can be removed for repair/replacement. To enable this, the edge of the inside lining is either made flush with the face of the pulley style or rebated slightly.

When the weathering has two steppings it is known as double sunk sill. An alternative of having width of sill of the full thickness of the frame is to arrange it so that the outside edge is flush with the outside face of the bottom sash. This ensures less danger of water driving through the joint between the sash and the sill than with a sill the full thickness of the frame.

For waterproofing, a metal tongue often fixed into corresponding grooves cut into the underside of the wooden sill and upper surface of the stone sill. A rebated joint between the two sills serves the same purpose as the metal tongue. The pulley on which the sash lines run –sash or axle pulleys are fixed in mortoises near the upper ends of the pulley styles. The edge of the outside lining projects for a distance (3/4”) beyond face of pulley style to form a rebate along which the outer (upper) sash slides.

The outer sash is kept in position by the parting lath which fits into groove in the pulley style. The groove for the inner (lower) sash is formed by the parting lath and a staff bead/stop bead which is secured by screws. The staff bead on the sill is 2-3 inches deep to allow the lower sash to be raised sufficiently for ventilation at the meeting rails without causing a draught at the bottom.

A vertical section at the head of the frame is similar to a horizontal section across the pulley style except that the back lining and parting slips are absent.The Sill of the frame is solid and weathered and should always be of hardwood preferably oak or teak. The sill has a width equal to the full thickness of the frame.

If one sash only slides and the other is fixed in the frame the window is single hung sash and frame window. When both sashes slide and are balanced by weights the window is known as a double hung sash and frame window.

Sashes of sash and frame window are balanced by cast iron or leaden weights. The best cord is employed for hanging sashes of ordinary size, while for very heavy sashes the sash lines are often of steel and copper. The staff bead and parting bead having been removed, the cords are passed over the axle pulley( which are best of brass to prevent corrosion) and are tied to the upper ends of the weights . The weights are passed through the pocket holes and suspended in the boxes.

The pocket pieces having been replaced the upper sash which slides in the outer groove is hung first the free ends of the chords being either nailed into grooves in the outer edges of the sash or screwed by knotting the ends after passing them through holes bored into the styles of the sash.The upper sash being hung the parting laths are fixed into the grooves in the pulley styles and the lower (inner) sash is hung in a similar manner, after which the staff beads are screwed in position.

If the cords for the upper sash are too long the weights will touch the bottom of the frame and cease to balance the weight of the sash before the latter is closed. If the cords for the lowersash are too short the weights will come in contact with the axle pulleys and thus prevent it from closing. The projecting ends of the styles are called joggles they assist in enabling the sashes especially in wide windows to slide more freely.