What Are the Parts of a House Roof?

Parts of a roof on a house work together to protect the building.
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Every part of a roof has a specific purpose to ensure protection of a house from the elements. Like a puzzle, each part works with the others to enhance the strength and security of the roof while providing flexibility for design options. Depending on the style, components of a house roof may vary beyond the basic parts. Once the foundation of the roof exists, then shingles, tiles or other types of materials complete the house roof.

1 Roof Truss

The roof truss holds the rafters.
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Common in the 21st century, the roof truss frames the rafters. Offering more strength than the traditional piecework framing method, the roof truss allows a greater variety of shapes in designing roofs because of the flexibility of the method. Built from wood, roof trusses provide renewable resources in environmentally friendly construction.

2 Rafters

Roof rafters make the roof skeleton.
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Making up the main skeleton of a roof, sloping rafters support the other layers of the roofing process. Spaced 16 to 48 inches (depending on roof design) rafters lay atop building walls. Typically, rafters extend beyond the outside wall, creating eaves, which help protect the building sides and windows from rain and snow runoff from the completed roof.

3 Ridge Board

The ridgeboard runs horizonally with attached rafters.
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The ridge board runs horizontally across the top of the roof formation where the tops of the rafters securely fasten, forming an angle. To prevent moisture from entering the attic or crawl space between the main building and the roof, the ridge board must have ridge caps or ridge cap shingles.

4 Sheathing or Decking

Sheathing or decking covers the rafters.
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Secured to the rafters and used as the base for nailing the other roof coverings, sheets of sheathing or decking normally consist of wood materials such as oriented strand board or plywood. Sheathing acts as another roofing barrier to protect against the elements.

5 Underlay

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Placed on top of the decking, the heavy felt paper underlay (sometimes called tar paper) attaches to the surface of the decking, adding another protective layer against moisture.

6 Flashing

Protectived metal flashing mold to the base of chimneys.
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Galvanized metal flashing protects the roof against leaks by molding around chimneys, roof vents, skylights and where heavy moisture runoff gathers. Flashing secures atop the underlay before attaching the shingles or other final roofing materials

Catalina Bixler's journalism career began in 1970. After five years as a publishing teacher, Bixler then published/edited NATO's U.S. 5th Army and 17th AF "Wiesbaden Post" newspaper. She holds a Bachelor of Arts in bilingual-journalism/community development from Redlands University, and a Master of Arts in adult education/training from the University of Phoenix.