Current through Register Vol. 54, No. 50, December 14, 2024
Section 21.21 - Wood side rails(a) Wood side rails shall not be made from low density wood but shall be of throughly seasoned material free of any of the following defects: (3) Checks over 6 inches long or over 1/2 inch deep.(5) Compression failures.(b) Cross grain in wood side rails of the different types and sizes of ladders when measured over a distance which will assure the determination of the general slope of the grain, not influenced by short, local deviations may not exceed the following: (1) In side rails of portable ladders having rungs for steps such as in extension, straight, trestle, or sectional ladders, when built to the minimum dimensions, the cross grain shall not exceed a slope of one in 15.(2) In side rails of portable ladders over 12 feet in length, having treads or cleats for steps, and in side rails of fixed ladders, the cross grain shall not exceed a slope of one in 12 when built to minimum dimensions.(3) In side rails of portable ladders under 12 feet in length, having treads for steps, the cross grain shall not exceed a slope of one in ten when built to minimum dimensions.(4) For ladders used indoors or otherwise protected from the weather, cross grain greater than that provided in paragraph (3) may be employed in side rails in accordance with the following schedule, if the size is increased to afford at least 15% greater strength than the minimum specified in § 21.32 (relating to side rails): (i) One in 12 may be substituted for one in 15.(ii) One in 10 may be substituted for one in 12.(c) Knots shall not appear in the narrow faces of side rails.(d) Knots in side rails shall not exceed one inch in diameter.(e) Knots appearing in the wide faces of side rails of minimum dimensions adjacent to the edges shall not exceed in diameter 1/12 the width of the face. The size of knots in the wide faces may increase proportionately from the size allowed adjacent to the edge to 2 1/2 times that size at the center line of the wide face. Knots appearing in side rails may be larger if compensated for by additional cross section and if the strength of the piece is equivalent to or greater than the strength of a similar piece of minimum dimensions. However, no knot, for which compensation for size is allowed, shall exceed, when located adjacent to the edge of the piece, 1/6 the width of the wide face.(f) Knots adjacent to the edges shall not appear within 1 1/2 inches, measured parallel to the length of the side rail, of the section occupied by a rung, tread, cleat or other knot.(g) Pitch pockets not exceeding 1/8 inch wide, two inches long and 1/2 inch deep are permitted in wood side rails if not more than one appears in each four feet of length.(h) Wood side rails shall be dressed on all sides and free from sharp edges and splinters.(i) Wood side rails shall be made from Eastern spruce or Sitka spruce or approved equivalent. Other woods may be suitable for ladder construction if so classified in §§ 21.61-21.72 (relating to wood classification). This section cited in 34 Pa. Code § 21.23 (relating to wood steps).