The erection of a typical platform  frame (referred to, imprecisely, as  rough carpentry in the architectÕs specifications) can best be understood by following this post s sequential  isometric diagrams, beginning with  Figure 5.19. Notice the basic simplici- ty of the building process: A platform  is built on top of the foundation.  Walls are assembled horizontally on the platform and tilted up into place.

Another platform or a roof is built on top of the walls. Most of the work is accomplished without the use of ladders or scaffolding, and temporary  bracing is needed only to support the walls until the next level of framing is  installed and sheathed.

The details of a platform frame  are not left to chance. While there  are countless regional and personal  variations in framing details and techniques, the sizes, spacings, and  connections of the members in a  platform frame are standardized  and closely regulated by building  codes, even down to the size and  number of nails for each connection (Figure 5.21) and the thicknesses and nailing patterns of the sheathing panels.

Figure 5.19
Step Three in erecting a typical platform frame building: the ground- fl oor platform.
Compare this drawing with the framing plan in Figure 5.17. Notice that the direction of
the joists must be changed to construct the cantilevered bay on the end of the building. A
cantilevered bay on a long side of the building could be framed by merely extending the floor joists over the foundation.

Figure 5.20
Alternative ways of constructing
an interior line of support for
ground-fl oor joists. Space is
left over the tops of the beams
in B and D to allow for drying
shrinkage in the joists.

Figure 5.21
Platform framing members are fastened according to this nailing schedule, which framing carpenters know by memory and which  is incorporated into most building codes and construction standards.

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