Tack strip is to be installed on each tread. It is required that pins on the tread point toward the riser. On a waterfall-type stair installation, tack strip is to be installed on risers also. Pins on risers point down to the tread. It is required that the gully between strips be slightly less than double the carpet thickness. Where a turned finish is desired, tack strip and cushion are about 1½ inches (38 mm) less than the carpet width, to allow for a turn under on each side of the stairs. Some stairs require tack strip on the sides to maintain the proper tension. When using a cap-and-band or contoured technique, tack strip is not used on riser.
NOTE: When staples are used in upholstering carpet on stairs, take care to separate pile yarns to avoid trapping yarns, resulting in visible distortion. If the edges are exposed, they must be edge sealed. Upholstery work needs to have no raw edges exposed. Any seams or joints must be sealed. Carpet seams need to be split in the direction of the balusters/spindles.