Anatomy of a Roof: Simple Guide to All Roof Parts

Structural Foundation

Trusses/Rafters

The wooden framework that supports your entire roof. Trusses are pre-built triangular frames, while rafters are individual beams. Both create the “skeleton” of your roof.

Ridge Board

The horizontal beam at the peak where both sides of your roof meet. It’s like the backbone of your roof structure.

Roof Decking (Sheathing)

Plywood or OSB panels nailed to the trusses/rafters, creating a solid base for everything else to attach to.

Weather Protection

Underlayment

A water-resistant barrier installed over the decking but under the final roofing material. Think of it as your roof’s backup raincoat.

Roofing Material

The visible outer layer that you see from the street:

• Asphalt shingles (most common)
• Metal panels or shingles
• Clay or concrete tiles
• Wood shingles
• Slate

Edges and Trim

Fascia

The vertical boards along your roof’s edge that give it a finished look and provide attachment points for gutters.

Soffit

The horizontal surface under your roof’s overhang, often containing ventilation holes for attic airflow.

Eaves

The part of your roof that extends beyond your home’s walls, creating an overhang that directs water away from your foundation.

Water Management

Flashing

Thin metal strips installed wherever your roof changes direction or meets other structures (chimneys, vents, valleys). These prevent water from sneaking into gaps.

Gutters and Downspouts

Collect rainwater from your roof and direct it away from your home’s foundation.

Drip Edge

Metal strips along roof edges that help water flow cleanly into gutters instead of backing up under roofing materials.

Ventilation System

Ridge Vents

Run along your roof’s peak to let hot air escape from your attic.

Soffit Vents

Allow cool air to enter your attic, working with ridge vents to create natural airflow that regulates temperature and moisture.

Common Roof Features

Chimneys

Require special flashing and maintenance since they create large openings in your roof.

Skylights

Windows in your roof that need careful installation and flashing to prevent leaks.

Plumbing Vents

Pipes that stick up from your roof to allow sewer gases to escape and maintain proper drainage.

Valleys

Where two roof sections meet at an angle, creating channels that direct water flow.