Roofing 101: Anatomy of a Roof & Common Roofing Terms
Roofing 101: Anatomy of a Roof & Common Roofing Terms
Understanding the parts of your roof can help you make informed decisions about repairs and replacements. Use this glossary to explore the components and terms commonly used in residential roofing projects.
Underlayment & Decking Components
#90 Rolled Roofing: Used in closed valley installations, this material has a felt or fiberglass base and a granulated top layer.
Decking (Sheathing): The wooden base layer of your roof, typically OSB or plywood.
OSB (Oriented Strand Board): Most common roof sheathing material used in modern construction.
Re-Decking: Replacing old decking with new 4×8 OSB panels to meet code or manufacturer requirements.
Replacing Decking: Swapping out damaged or deteriorated decking found during tear-off.
Ice and Water Shield: Self-sealing waterproof barrier installed at vulnerable areas like eaves and valleys.
Roofing Felt (#15/#30): A protective layer between the decking and shingles. #30 is thicker and more durable.
Flashing, Vents & Roof Protection
Drip Edge: Metal flashing installed at the edge of the roof to guide water away and prevent rot.
Step Flashing: Used where the roof meets walls to direct water safely away.
Storm Collar: Flashing installed at pipe penetrations to prevent water infiltration.
Pipe Jack: Flashing boot installed over plumbing vent pipes to ensure a watertight seal.
Rain Cap: Covers exhaust vents to prevent water entry while allowing proper ventilation.
Ridge Vent: Installed at the peak to release heat and moisture from the attic.
Box Vent: Static vent near the roof peak for hot air release.
Soffit Vent: Intake vents under eaves that work with roof vents to improve airflow.
Roof Structure & Design Features
Eave: The edge of the roof that overhangs the walls.
Rake: Sloped edge of the roof from eave to ridge.
Ridge: The peak line where two roof slopes meet.
Valley: Channel formed where two roof planes meet. Can be open or closed depending on shingle layout.
Gable: The triangular section of a wall beneath the roof slope.
Beauty Course: Additional shingles that cover flashing for improved appearance.
Roof Types & Materials
EPDM: Rubber-based membrane used on low-slope roofs for waterproofing and flexibility.
Modified Bitumen: A thick, granulated asphalt product for flat or low-slope roofing.
Asphalt Shingles: The most common residential roofing material, offering affordability, weather resistance, and style variety.
Architectural Shingles: Also known as dimensional shingles, these are thicker and more durable than 3-tab shingles with enhanced aesthetic appeal.
Impact-Resistant Shingles: Specially engineered to resist hail damage and may qualify for insurance discounts.
