Window sills in brick buildings should be of brick or stone.
Cement, unless pre-cast, is not well adapted for the purpose. Brick
window sills are preferable to stone for, besides adding a charming
touch to the building, they are inexpensive since they are of the
same material as the wall and placed by the same workmen who lay up
the wall, thus obviating the necessity of additional labor to place
the heavy stone. Brick for sills should be laid on edge and pitched
approximately at an incline of 1 inch in 6 to shed the water. They
should also project at least an inch beyond the face of the wall to
form a drip, and be laid in rich cement mortar composed of equal
parts of cement and sand, with joints well filled and finished with
a hard smooth surface. Door sills may be of wood, brick, or stone.
In case of a stone sill, it should be exactly the height of either
two or three courses of brick.
[Sidenote: Window Frames]
The window frames are set by the carpenter on top of the sill in
a thin bed of mortar. When they are leveled, plumbed, and braced,
the brickwork is carried up around the jambs or weight boxes, as
shown in Fig. 24, always making certain that the corner or jamb of
the brick opening is perfectly plumb. Great care should be taken
to fill solid with mortar the spaces between the brickwork and the
window frame, to stop the wind.