Chapter 10 Floor Framing 255 2'– 0" 2'– Maximum Minimum0" Rim board or sawn wood Blocking ½" sheathing on at least one side of joists. Nail with 8d nails spaced 6" o.c., top and bottom flange. If applied on both sides of joist, offset nails by 3" to avoid splintering. Goodheart-Willcox Publisher Figure 10-37. Framing a cantilevered section of a floor frame when the joists run perpendicular to the supporting wall. Blocking holds the joists vertical, adds rigidity, and closes up the space to provide a firestop. Joist direction Header Foundation Overhang distance Joists Double joist Minimum two times overhang distance Goodheart-Willcox Publisher Figure 10-38. When cantilevered joists run parallel to the supporting wall, extend the overhanging joists inward two to three times the length of the overhang. Always check local codes for exact requirements. using doubled joists of a smaller dimension is accept- able, Figure 10-39. Reducing the distance between joists provides additional support. When the area is large, add steel or wood girders and posts. Bathrooms must support unusually heavy loads—heavy fixtures like bathtubs and often the additional weight of a tile floor. The fixed dead load imposed by a tile floor averages around 30 lb. per sq. ft. The load from bathroom fixtures adds from 10 to 20 lb. per sq. ft., for a total of 40–50 lb. dead load. In addition, it is frequently necessary to cut joists to bring in water service and waste drains. Therefore, take special precautions in fram- ing bathroom floors to provide adequate support. Copyright Goodheart-Willcox Co., Inc.