Walls of concrete masonry units (CMU).
(1) Wall thickness. CMU blocks used for bearing walls must have a minimum nominal thickness of six inches.
(2) Rebar cover. All rebar must be:
(a) Placed within the openings of the hollow masonry units;
(b) Completely embedded in mortar or grout; and
(c) Have a minimum cover of three-fourth inch including the masonry unit. Where masonry is exposed to weather, one and one-half inches of cover is required. Where masonry is exposed to soil, two inches of cover is required.
(a) Masonry walls must have both vertical and horizontal reinforcement. Spliced rebar must overlap at least twenty inches. Reinforcement must be placed prior to grouting. Bolts must be accurately set and held in place to prevent dislocation during grouting.
(b) Vertical reinforcement must consist of No. 4 rebar placed four feet on center along the full length of walls, on each side of window and door openings, and at corners. Vertical rebar must extend from the top of the foundation to the top of the wall and be grouted in place.
(c) Horizontal reinforcement must consist of bond beams located at four feet above the foundation and repeated at four foot intervals, including one at the top of the wall. Bond beams must be constructed using bond beam masonry units with one continuous No. 4 rebar, grouted in place.
(d) Lintels over door and window openings must be provided and must be sixteen inches deep consisting of bond beam or lintel masonry units extending over the opening and at least twenty inches beyond each side, and with four pieces of No. 4 rebar running the full length of the lintel, grouted in place. The span of lintels over openings must not exceed twelve feet.
(a) The grout space must be clean so that all spaces to be filled with grout do not contain mortar projections greater than one-half inch, mortar droppings or other foreign material. Cleanouts must be provided where necessary to clean and clear the spaces prior to grouting. When cleanouts are needed, they must be sealed before grouting.
(b) Grout must be placed so that all spaces designated to be grouted must be filled with grout and the grout must be confined to those specific spaces.
(c) Where bond beams occur, the grout pour must be stopped a minimum of one-half inch below the top of the masonry.
[Statutory Authority: RCW 70.114A.081
. WSR 99-03-065, § 246-359-440, filed 1/18/99, effective 2/18/99.]