Parts of a Roof, Explained
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Get free quotesRoof components glossary
| Part | What it is |
|---|---|
| Ridge | The horizontal peak where two roof slopes meet at the top. |
| Hip | The external angle where two roof slopes meet, running from ridge to eave (common on hip roofs). |
| Valley | The internal angle where two roof slopes meet and drain toward each other — a common leak point if flashed poorly. |
| Eave | The lower edge of a roof slope that overhangs the exterior wall. |
| Rake | The sloped edge of a roof at a gable end, running from eave to ridge. |
| Decking (sheathing) | The structural wood panels (usually OSB or plywood) fastened to the rafters/trusses that everything else attaches to. |
| Underlayment | A water-resistant layer installed over the decking, beneath the shingles, as a secondary moisture barrier. |
| Ice-and-water shield | A self-adhering waterproof membrane installed at eaves, valleys, and penetrations, required in many cold climates to stop ice-dam leaks. |
| Flashing | Metal (or sometimes rubber) material installed at any joint, valley, or penetration — chimneys, vent pipes, walls — to direct water away instead of letting it seep in. |
| Drip edge | A metal strip installed along eaves and rakes that directs water away from the fascia and into the gutter. |
| Soffit | The material covering the underside of the roof overhang; often vented to let air into the attic. |
| Fascia | The vertical trim board along the roof edge, usually where gutters are mounted. |
| Ridge vent / soffit vent | Ventilation components that let hot, moist attic air escape (ridge) while pulling fresh air in (soffit) — see our roof ventilation guide. |
| Truss / rafter | The structural framing members that hold the roof's shape and support the decking. |
Pro tip from our network contractors
When you get a roofing estimate, check whether it explicitly lists ice-and-water shield, new flashing at valleys/penetrations, and a drip edge — these are the components most often quietly left off a cut-rate bid to hit a lower price, and they're exactly the parts that prevent leaks.
Why this vocabulary matters when you're getting quotes
A roofing estimate that just says "install new shingles" tells you almost nothing about what's actually being done underneath. Understanding these terms lets you ask specific questions — is the decking being inspected and replaced where needed, is new flashing going in at the chimney and valleys, is ice-and-water shield included at the eaves — and compare quotes on substance instead of just a bottom-line price. See how to choose a roofing contractor for the full vetting process.
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Get free quotesFrequently asked questions
What is roof flashing?
Flashing is metal (or sometimes rubber) material installed at any roof joint, valley, or penetration — like chimneys, vent pipes, and skylights — to direct water away and prevent leaks at those vulnerable points.
What's the difference between a ridge and a valley?
A ridge is the horizontal peak where two roof slopes meet at the top. A valley is the internal angle where two slopes meet and drain toward each other — valleys handle more water flow and are common leak points if not flashed correctly.
What is roof decking?
Decking (or sheathing) is the structural wood panel base — usually OSB or plywood — fastened to the rafters or trusses, which everything else in the roof system (underlayment, shingles, flashing) attaches to.
Why does my roofing estimate mention ice-and-water shield?
It's a self-adhering waterproof membrane installed at eaves, valleys, and penetrations that acts as a secondary barrier against leaks — especially important in cold climates prone to ice dams. Many codes require it in these areas.
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