Lap sidings can be installed horizontally or vertically. For horizonal applications, start with the bottom course and work up with the bevel sides of the channels pointing upwards. Allow a 1/8 in. expansion gap between pieces if the siding is air-or-kiln-dried. Do not nail through overlaps. For siding up to 6 in. wide, use one nail one inch up from the lap. Face nail with two nails per bearing for 8 in. patterns and wider, keeping nails 2-1/2 to 3 in. apart to allow for dimensional movement without splitting (see Figure 6). For vertical applications, siding should be nailed to horizontal blocking lines or furring strips (see Wall Construction).

Table 6: Recommended Overlap for Lap Cedar Siding

Thickness (in)	Nominal Board Width (in)	Finished Width (in)
3/4	6, 8, 10	5-1/2, 7-3/8, 9-3/8
5/8	6, 8	5-1/2, 7-3/8