Wood Framed Roofs
Wood-framed roofs fall into the same category as wood-framed walls. They simply disintegrate in a major tornado. Next time you see TV news films of a tornado hitting a house, observe what goes first. Watch the roof!
Insulated Reinforced Concrete Roof Decks
Because of their weight, concrete roofs typically must be supported by concrete walls.
In order to assure that the concrete shell structure will develop its full capability to resist the imposed destructive forces, it is essential that the roof structure provide a competent structural diaphragm incorporating a cast-in-place reinforced concrete slab or well-connected precast concrete planks in order to develop the full potential of a concrete shell.
There are several manufacturers of insulating concrete forms in North America for cast-in-place concrete slab systems.
Ridge And Valley Beams
There can be a number of different approaches to the configuration of ridge and valley beams that might be used and will likely be developed by individual contractors. Figure 7 suggests several possibilities that have been shown to be workable.