Learn About Roof Structure and Design

Learn the different parts of common roofing structures and the types of roof designs.
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©2007 Dorling Kindersley Limited

©2007 Dorling Kindersley Limited

©2007 Dorling Kindersley Limited

©2007 Dorling Kindersley Limited

©2007 Dorling Kindersley Limited

©2007 Dorling Kindersley Limited

©2007 Dorling Kindersley Limited

Roof Structure

A typical roof is constructed from a roof truss, covered with roof sheathing, underlayment, and a roof covering on top. The layers are carefully overlapped to ensure the roof is fully waterproof.

Valley

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.

Hip

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.

Deep Eaves

Typically, deep eaves should have 12 inches (300 mm) or more continuously vented to ensure that sufficient air intake is available. This is required to properly vent the attic.

Shallow Eaves

Typically, shallow eaves have less than 12 inches (300 mm) of continuous venting. This is popular among more contemporary designs. You must also vent to ensure proper air circulation in the attic.

Outlook Overhang

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

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.