Parts of a roof
- Eave
- The lower, horizontal edge of a roof plane, usually with a gutter. Measured in linear feet for starter strip, drip edge and ice barrier.
- Rake
- The sloped edge of a gable, from eave to ridge.
- Ridge
- The horizontal peak where two planes meet at the top. Covered with ridge cap.
- Hip
- A sloped external corner where two planes meet, running from the ridge down to an eave corner.
- Valley
- A sloped internal corner where two planes meet and water runs together. Needs valley lining or ice-and-water shield.
- Facet (plane)
- One flat face of a roof. A gable roof has 2; real homes often have 8–20.
- Gable roof
- Two planes meeting at a ridge, with triangular wall ends.
- Hip roof
- Planes slope down on all sides; no gable walls.
- Dormer
- A small roofed structure projecting from a sloped roof, usually with a window.
- Overhang
- The part of the roof that extends past the walls. Included in roof area, missing from the house’s floor area.
- Fascia
- The board along the eave that the gutter attaches to.
- Soffit
- The underside of the overhang, often vented.
- Deck (sheathing)
- Plywood or OSB boards the roof covering is fastened to.
- Step wall / sidewall
- Where a roof plane meets a vertical wall; needs step flashing.
Measurement terms
- Pitch
- Rise in inches per 12 inches of horizontal run, written 6/12. Pitch chart.
- Slope
- Often used for pitch; also expressed in degrees or percent.
- Slope factor (pitch multiplier)
- √(1 + (pitch/12)²): converts footprint to sloped surface. 6/12 → 1.118.
- Square
- 100 sq ft of roof surface. More.
- Footprint
- The area under the roof seen from above, overhangs included.
- Waste factor
- Extra material added for cuts. More.
- Low-slope roof
- Below about 2/12–3/12; needs membrane roofing rather than shingles.
- Predominant pitch
- The pitch covering most of the roof area.
- Linear feet (LF)
- Length, used for eaves, rakes, ridges, hips, valleys, gutters and flashing.
Materials
- Underlayment
- A water-resistant layer over the deck, under the shingles: felt or synthetic.
- Ice and water shield
- Self-adhering membrane at eaves, valleys and penetrations to stop ice-dam and wind-driven leaks.
- Drip edge
- Metal edge at eaves and rakes that directs water away from the fascia.
- Starter strip
- The first course along the eaves (and often rakes) that seals the edge of the first shingle row.
- Hip and ridge cap
- Shingles made or cut to cover hips and ridges.
- Flashing
- Metal that seals joints: step flashing at walls, counter-flashing, chimney and pipe flashing.
- 3-tab shingle
- Flat, single-layer asphalt shingle with three tabs.
- Architectural shingle
- Thicker, laminated asphalt shingle with a dimensional look; the most common choice today.
- Standing seam metal
- Metal panels joined by raised seams with hidden fasteners.
- TPO / EPDM / modified bitumen
- Membranes for low-slope and flat roofs.
- Ridge vent
- A vent along the ridge that lets attic air out.
- Bundle
- A package of shingles; usually 3 per square.
On the job
- Tear-off
- Removing the existing roof covering down to the deck.
- Overlay (layover)
- Installing new shingles over one existing layer, where code allows.
- Re-deck
- Replacing damaged sheathing.
- Takeoff
- The list of quantities measured from the roof for a bid.
- Supplement
- An additional insurance claim item found after the first estimate.
Questions
What is the difference between a hip and a valley?
Both are sloped lines where two roof planes meet. A hip is an outside corner (water runs away from it); a valley is an inside corner (water runs into it).
What is the difference between an eave and a rake?
The eave is the lower horizontal edge of a roof plane; the rake is the sloped edge of a gable.