shall be lapped not less than 5 inches. In slabs on ground, precast concrete blocks may be substituted for chairs. c. Supports: Reinforcement shall be accurately placed and securely tied at all intersections and splices with 18-gage black annealed wire, and shall be securely held in position during the placing of concrete by spacers, chairs or other approved supports. Wire tie end: shall point away from the form. For reinforcement in the bottoms of slabs and beams, the supports shall be sufficiently heavy and sufficient in number to properly carry the steel reinforcement. 5-21