Fires within sills, headers, joists and other structural members can take hours to develop, because they can wait patiently for the right amount of air to create a working fire within the walls.

Sound structural integrity relies on proper placement of building parts and adequately sized spans. Span decisions usually are left to architects and engineers, however, the do-it-yourselfer ...

I-joists can be ordered and designed for each application, or a stock size, ... With longer I-joists, a center support beam or header will be needed to prevent "bouncing" floors.