Download PDF version (297.1k) Log In or Register to view the full article as a PDF document.

Floor Framing With Steel Continued

Framing a second floor. If the second-floor steel joists are supported by a wood-framed wall, the procedure is almost the same: The rim track is screwed to the top plate and the joists are screwed to the track. On a steel-framed wall, the rim track is screwed to the top track (the steel equivalent of the top plate) of the supporting wall, and the bottom flanges of the joists are also screwed to the top track (Figure 7).

Image

Figure 7. Second-floor joists are fastened to the top track of a steel-framed wall with screws driven through the joist flanges. OSB sheathing will be screwed to both studs and rim track for a secure connection between floor and wall framing.

Web stiffeners are usually required at the joist ends, as for the first floor. Cantilevered joists also require a web stiffener where they pass over the supporting wall (Figure 8).

Image

Figure 8. A framer clamps the cantilevered floor joist to the top track before screwing it in place. Additional web stiffeners will be added where the joists bear on the plate. Floor cantilevers of up to 2 feet are permitted by the prescriptive method.

Regardless of whether the walls are framed with wood or steel, the upper edge of the OSB will fall about one foot below the rim track, provided that the first course of OSB starts at foundation level, as described earlier. The next sheet of OSB ties the second-floor rim joist solidly to the studs and plate beneath. Clip angles and nested assemblies. Framing openings in a steel floor is similar to framing openings with wood. In place of the traditional double trimmer at each side of the opening, a nested assembly consisting of a C-joist and a track section is used (Figure 9 below). Steel headers are assembled the same way. Connections are made with screws and clip angles, which are the steel framer's equivalent of joist hangers.

Framing Floor Openings

Image

Image

Figure 9. Floor openings are simple if you think of nested track and joist sections as double trimmers or headers, and clip angles as joist hangers.