Roof and Roofing Parts

What happens when something goes wrong with your roof? When the time comes for replacement or repair, will you have proper knowledge of all the parts to identify the problem, or even describe it to your contractor? Below, you will find all the parts of your roof concisely defined for quick and easy reference and identification.


  • Cornice: The points of the roof that project from the side walls of the house.
  • Courses: Rows of shingles or tiles installed horizontally.
  • Decking or Sheathing: The surface to which the shingles and/or panels are applied. It usually consists of either plywood or oriented strand board (OSB).
  • Dormer: A structure (composed of walls and a roof) surrounding a window that projects from a sloped roof.
  • Drip Edge: The metal, L-shaped strip that runs along the roof's edge and allows water to drip clear of the deck and siding.
  • Eaves: The lower edges of a roof that extend beyond the edge of the house structure.
  • Fascia: The trimboard that covers the rafter end of the eaves and is located behind the gutter and the eaves.
  • Flashing: Sheet metal that is used at different planes on a roof to prevent leakage.
  • Frieze Board: The frieze board is located at the top of a house's siding and forms a corner with the soffit.
  • Gable: The triangular upper portion of a wall that closes the end of a ridged roof, above the main portion of the house.
  • Hip: When a roof's supporting walls adjoin, the external angle at the junction of its two sides is known as the hip.
  • Joist: The horizontal structure in a flat roof over which sheathing is nailed.
  • Louvers: The slatted devices that are installed in a gable or soffit in order to ventilate and equalize air temperature under the roof deck.
  • Rafter: The slanted structural support that sheathing is nailed to.
  • Rake: The slanting edge on a gabled roof which extends past the end of the house.
  • Ridge: The horizontal line found at the top edge of two sloping roof planes.
  • Slope or Pitch: The number of inches of vertical rise in a roof, per 12-inches of horizontal distance.
  • Soffit: These boards go along the underside of the
  • Truss: A framework of engineered components that supplement the rafters and support the roof.  
  • Underlayment or Felt: Usually made of a combination of asphalt and either paper or rags, this “tar paper” is placed on top of the decking before roofing materials are installed. It offers additional moisture protection.
  • Valley: A less than 180-degree angle where two sloping roof sections join.