246 Section 2 Foundations and Framing and stiffness. Span tables for I-joists are avail- able from the manufacturer. Code Note Building codes typically specify allowable span distances for floor joists based on the size of the joist and the type and grade of wood. Always verify that the joist sizes for the project are acceptable to the applicable building code. 10.4.1 Laying Out Joists When laying out joists, begin by carefully studying the plans. Note the direction the joists are to run. Also, become familiar with the location of posts, columns, and supporting partitions. The plans may also show the centerlines of girders. The position of the floor joists can be directly laid out on the sill, Figure 10-22. In platform con- struction, the joist spacing is usually laid out on the band joist rather than the sill. Band joists are those joists that sit on the sill and to which other floor joists are butted and attached. They are also called joist headers or rim joists. The position of an intersecting framing member may be laid out by marking a single line and then placing an X to indi- cate the side of the line the joist is to be installed, Figure 10-23. When using solid wood joists, the crown of the joist should be turned upward. The crown, also called a crook, is a slight warping. Rather than having to measure each indi- vidual joist space with a steel tape, some car- penters make a master layout (called a rod) on a strip of wood. Use it to transfer the layout to band joists or the sill. The same rod is then used to make the joist layout on girders and the opposite wall. When the joists are lapped at the girder, the X (joist location) is marked on the other side of the layout line for the oppo- site wall. In this case, the spacing between the stringer and first joist is different from the reg- ular spacing, Figure 10-24. As mentioned earlier, some plans call for the sills and band joists to be set back from the edge of the foundation to leave a ledge around the outside of the sill. This ledge may be 1″ or less to accommodate the sheathing, or several inches to accommodate masonry veneer. When the sheath- ing is applied, it is flush with the foundation wall. In Figure 10-24B and Figure 10-24C, the sill is flush to the edge of the wall, but the band joists are offset. Joists are doubled where extra loads must be supported. When a partition runs parallel to the joists, a double joist is placed underneath. Doubled joists placed under partitions that are to carry plumbing or heating pipes are usually spaced far enough apart to permit easy access. In this case, blocking is placed between the joists so that they act as a single piece, Figure 10-25. 15 1/4" Sill sealer Stud or joist spacing permits efficient use of modular materials 16" 16" 16" Goodheart-Willcox Publisher Figure 10-22. After the sill is attached to the founda- tion, locations for studs or joists may be marked using a square. Layout mark Goodheart-Willcox Publisher Figure 10-23. How to mark the actual location of fram- ing members being attached to a band joist. Layout marks show where the edge of a joist should be. The X indicates which side of the line the joist should be positioned. Copyright Goodheart-Willcox Co., Inc.