Parts of a roof
The names roofers use, drawn twice: the lines you see from above, and the layers you would see if you cut through the edge of the roof. Knowing them makes a roofing quote readable.
The lines of a roof
- Ridge
- The level peak where two slopes meet at the top. Covered with ridge cap shingles, often over a ridge vent.
- Hip
- A sloping outside corner where two roof slopes meet, running from the ridge down to a corner of the house.
- Valley
- A sloping inside corner where two slopes meet and water collects. The roof's most leak-prone line.
- Eave
- The lower, level edge of a slope, where water runs off and the gutter hangs.
- Rake
- The sloped edge at a gable end, running from eave to ridge. It gets drip edge but no gutter.
- Gable
- The triangular wall under a rake, at the end of a gable roof.
The layers, bottom to top
Under it all are the rafters or trusses: the roof's frame.
- Roof deck (sheathing)
- Plywood or OSB boards nailed over the rafters; everything else is fastened to it. Soft or rotten decking is replaced during a re-roof.
- Underlayment
- A water-resistant sheet (synthetic or felt) over the whole deck, the backup layer under the shingles.
- Ice and water shield
- A self-sticking rubberized membrane at the eaves, in valleys and around penetrations, where ice dams and heavy water flow push water uphill.
- Starter strip
- The first course along the eaves and rakes, with adhesive that seals the edge of the first row of shingles down.
- Shingles
- The visible layer that sheds water. Architectural (laminated) shingles are the standard today.
- Ridge cap
- Thick, folded shingles that cover the ridge and hips.
Edges, joints and details
- Drip edge
- An L-shaped metal strip along the eaves and rakes that throws water clear of the fascia.
- Fascia
- The vertical board along the eave that the gutter is fastened to.
- Soffit
- The underside of the overhang, usually vented to let air into the attic.
- Gutter and downspout
- Catch the water at the eaves and carry it to the ground and away from the foundation.
- Flashing
- Metal pieces that seal every joint: walls, chimneys, valleys, vents and skylights.
- Roof vents
- Intake vents in the soffit and exhaust vents near the ridge keep air moving through the attic.
- Pipe boots
- Flanged rubber or lead collars around plumbing vent pipes; often the first thing to leak.
- Dormer
- A small roofed structure with a window that projects from a sloped roof, adding valleys and flashing.
- Cricket (saddle)
- A small peaked roof behind a chimney that splits the water around it.
The roof's shape decides how many of these lines it has: see types of roofs. A quote that names each part — new drip edge, all step flashing replaced, ice and water shield in the valleys — is easier to compare than one that just says “new roof”.
Roof part questions
What are the parts of a roof called?
The lines: ridge, hips, valleys, eaves and rakes. The layers, from the bottom: rafters or trusses, roof deck, underlayment, ice and water shield, starter strip, shingles and ridge cap. The edges and details: drip edge, fascia, soffit, gutters, flashing, vents and pipe boots.
What is the difference between an eave and a rake?
The eave is the level bottom edge of a slope, where water runs off and the gutter hangs. The rake is the sloped edge at a gable end. Both get drip edge; only eaves get gutters.
What are the vents on top of a roof for?
They let hot, damp air out of the attic. Air comes in through soffit vents at the eaves and leaves through ridge vents or box vents near the top; the balance keeps shingles cooler, stops condensation and helps prevent ice dams.
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