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19 Parts of a Roof on a House (Detailed Diagram)

Collage of different types of roofs.

Like many aspects of a home, a roof is fairly complex. There are quite a few parts of a roof on a home including different layers and features.

Below we created a very helpful custom diagram that illustrates the various features and layers of a typical roof. For more information about roofs, check out our types of roofs article and diagrams.

Related: Hip Roof Styles | Homes with Gambrel RoofsTypes of Roof OverhangsHow Long Do Roofs Last

Parts of a house roof diagram

Ridge Board: A horizontal timber or metal resting at the peak of the roof. The rafters and trusses are connected to the ridge board for a cohesive framework.

Solid Decking: A composite decking made of solid materials. It resembles real wood and particularly strong and stable for bearing heavy load.

Felt Underlayment: It is a waterproofing layer made of regular felt, stacked above the solid decking board and then completely covered by the shingles or other roofing materials.   

Shingles: Roof covering typically of flat and rectangular shapes and made of various materials such as slate, wood, flagstone, plastic, metal and composite materials.

Vent Pipe Flashing: An external installation on the roof that uses the vent pipe system to prevent water seeping in and create damage.

Skylight: A window installed on the roof or ceiling for the purpose of daylighting.

Chimney Flashing: A waterproofing seal installed at the intersection of the roof and chimney and used to prevent moisture penetration.

Chimney: A vertical structure through the roof that ventilates smoke and combustion gases from a fireplace, boiler or stove to the outside atmosphere.  

Collar Beam: The horizontal beam connecting two rafters that intersect at the ridge.

Rafter: One of a series of diagonal members of the truss that meet at the apex in order to support the roof deck and its loads.

Valley Flashing: A waterproofing seal installed along the roof’s valley line.

Valley Underlayment: A waterproofing layer that protects the roof valleys from leaking.

Spaced Sheathing: Also called Skipped Decking, it refers to the installation of the flat panels by spaces apart and results to a ladder-type appearance.

Fascia: The sheath covering the ends of the rafters.

Lookout: The horizontal joist projecting in cantilever from the wall plate.

Rake: The inclined sides of a gable end.

Gutter: A duct for water discharge system for a building.

Downspout: The channel that transports rainwater from the gutter.

Splash Block: Found underneath the downspout and used to transport the rainwater from the gutter in a direction away from the house.