When the outside casing is set flush with the boarding the band mould or outside architrave, C, should be put on after the frame is fixed in place, and the sheathing paper should be extended on to the casing and C nailed over it, and also over the joint between the casing and the boarding. If the casing sets outside the boarding the sheathing paper should be put on around the opening before the frame is set and the outside casing nailed over it.

Flashing. - When the band moulding or the casing is tightly nailed over sheathing paper no flashing is needed on the sides when the wall is covered with siding or clapboards, and if good thick and tough paper is used it may be omitted for shingles, although it is much safer to flash each course of shingles with pieces of tin, as shown in the figures. The top of the frame, however, should always be flashed, no matter how the frame is made, unless the shingles project over the * casing. The best materials for this flashing are lead or zinc, although tin is often used. The flashing should be turned over the edge of the casing or band moulding, as at F, Fig. 96, and securely tacked or bradded. The bottom of the sill should be rebated for the shingles or clapboards, as shown in the figures.