High Wind Roof Rafter Designs

Let s consider a basic gable wood roof framing design.

High wind roof rafter designs.

This approach conforms to my general design philosophy when in comes to the structural design of houses. More they usually claim that 4 12 is the lowest you can go without any special underlayment. Since wind suction forces on the leeward side of a building can be essentially as high as the pressure forces on the windward side limitations are placed on the height above grade. This guide is ultimately about the top 20 styles of roof designs.

Flat or actually more like nearly flat single slope think one high wall with a roof that slopes down to a lower wall. Just as there are many types of roofs with many roof parts there are many different types of roof trusses this extensive article explains through a series of custom truss diagrams the different truss configurations you can use for various roofs. First you ll want to find the pitch of your rafters which will help you find the length of your rafters. While this article focuses on configurations we also have a very cool set of illustrations showcasing the different parts anatomy of roof trusses.

The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial. Before we get there we still have more ground to cover. Here we have a wood framed gable roof. Hold down brackets are brackets that are bolted nailed or screwed to wall studs or posts and anchored to the construction below concrete masonry or wood to hold down the end of a member or assembly i e shear wall.

Floor beam span tables of residential structural design we will now look at roof rafter and beam design. Use this calculator to find your rafter length. Baffled vents slow airflow and prevent wind driven rain from entering the attic through the ridge vent. The numbers vary depending on your local design wind speed zone but the bottom line is that you can use the same hardware here that you would use if the roof were an ordinary 12 pitch roof with straight rafters.

It helps to understand the 4 basic geometric shapes that are common to most types of roofs. Rafter clips and roof tie downs are straps or brackets that connect roof framing members to wall framing to resist roof uplift loads associated with high wind conditions. Bond beam depth and minimum horizontal reinforcement varies with design wind velocity ceiling height roof truss span and spacing of vertical wall reinforcement. Clay or concrete spanish tile is also a common roofing material in southern parts of the country and is resistant to high winds as are stone and stucco exterior siding materials.

Continuing on from part 3. Wrap hurricane straps over the top of the roof truss or rafter.