Learn about the different parts of common roofing structures and the types of roof designs.
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Roof designs can be complicated. In order to shape a roof, hips and ridges combine with the trusses to create the spaces inside the home. The shape of the roof must also shed water effectively. When detailing a roof hip or ridge, it is important to make the connection secure, and to properly install the sheathing, underlayment, and flashing materials so that water does not enter the structure. Shown here are a few common details used to create most rooflines.
A valley is used if the external walls of the home turn an internal corner. It is designed to direct water down towards its intersection point, and then the water runs down the valley and off the roof.
A hip design can sometimes be found at a corner of the external walls of the home. Just like a mountain, a hip allows rainwater and snow to fall off either side of the hip and then slide off of the roof.
Typically, deep eaves should have 12 inches or more continuously vented to ensure that sufficient air intake is available. This is required to properly vent the attic.
Typically, shallow eaves have less than 12 inches of continuous venting. This is popular among more contemporary designs. You must also vent to ensure proper air circulation in the attic.
Outlook overhang is shown here on the gable end of the home. It is supported by look-outs, which extend from the adjacent rafter. Although it requires more material. This is a sturdy method.
Ridgehung overhang is less material intensive than outlook overhang. In this design the overhang is hung from the ridge at the apex of the roof. The boards are installed flat.
Excerpted from Do It Yourself Home Improvement
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