780 CMR, CHAPTER 51, ch. R5, R506 - Allowable joist spans

Add new section R506.1.1 Control Joints as follows:

R506.1.1 Control Joints. Slabs shall be constructed with control joints having a depth of at least one quarter of the slab thickness but not less than one inch (25 mm). Joints shall be spaced at intervals not greater than 30 feet (9144 mm) in each direction. Control joints shall be placed at locations where the slab width or length changes.

Exception: Control joints may be omitted when the slab is reinforced in accordance with Table R506.1.1. Reinforcement shall be placed at the mid-depth of the slab or two inches (51 mm) from the top of slabs greater than 4 inches (102 mm) in thickness.

Add new Table R506.1.1 as follows:

Table R506.1.1

MAXIMUM DIMENSION OF SLAB OR DISTANCE BETWEEN CONTROL JOINTS (ft.)						WWF WIRE	WWF WIRE SIZE
Slab Thickness (in.)
3.5	4.0	4.5	5.0	5.5	6.0
42	36	32	29	26	24	6 x 6	W1.4 x W1.4
59	52	46	42	38	35	6 x 6	W2.0 x W2.0
86	75	67	60	55	50	6 x 6	W2.9 x W2.9

Notes

780 CMR, CHAPTER 51, ch. R5, R506

Amended by Mass Register Issue 1532, eff. 10/11/2024.