ROOFING GLOSSARY · CHARLOTTE, NC & ACROSS NORTH CAROLINA
Roofing Terms Glossary — The Parts of a Roof, Explained
Estimates and inspection reports are full of words like decking, flashing, drip edge, and square. This roofing glossary defines 30+ common roofing terms in plain English so you can read your quote, ask better questions, and make a confident decision about your North Carolina roof.
How to Use This Glossary
Talk Roofing Like a Pro
A roof is a system of parts that work together to keep water out and air moving. When you understand what each piece does, a roof inspection report or a cost estimate stops feeling like a foreign language. The terms below are listed alphabetically — skim for the word you saw, or read straight through for a quick roofing education.
Glossary · A–F
Roofing Terms A to F
- Architectural shingle
- A thicker, layered asphalt shingle (also called laminated or dimensional) that gives a richer look and longer life than flat 3-tab shingles. The most popular choice in North Carolina.
- Boot (pipe boot)
- A flexible collar that seals around a plumbing vent pipe where it passes through the roof. Cracked or dry-rotted boots are a frequent, easy-to-miss leak source.
- Course
- A single horizontal row of shingles. Roofs are installed course by course, from the eave up to the ridge, each overlapping the one below.
- Decking (sheathing)
- The layer of wood boards or plywood/OSB fastened to the rafters. Everything else — underlayment, shingles, flashing — is attached to the decking. Rotted decking is replaced during a re-roof.
- Drip edge
- A metal strip installed along the roof edges (eaves and rakes) that directs runoff into the gutters and away from the fascia and decking, preventing rot.
- Eave
- The lower edge of the roof that overhangs the exterior wall — the part water runs off into your gutters.
- EPDM
- A durable synthetic rubber membrane used on flat and low-slope roofs, common on commercial buildings. Known for weather resistance and long service life.
- Fascia
- The vertical board running along the roof’s edge behind the gutters. It caps the ends of the rafters and provides a mounting surface for gutters.
- Dormer
- A framed structure that projects out from a sloping roof, usually with a window. Dormers add character and headroom but create extra valleys and flashing that must be sealed carefully.
- Flashing
- Thin metal pieces installed at joints and transitions — around chimneys, skylights, walls, and in valleys — to seal out water where the roof plane changes. Failed flashing is a leading cause of leaks.
Glossary · G–P
Roofing Terms G to P
- Gable
- The triangular section of wall at the end of a pitched roof where two slopes meet at a ridge. A “gable roof” has two sloping sides forming this shape.
- Granules
- The mineral coating on asphalt shingles that shields them from UV and adds color. Losing granules — often visible in the gutters — is a sign a roof is aging or storm-worn.
- Hip
- The external angle where two sloping roof sections meet. A hip roof slopes down on all sides, which handles wind well — a plus in storm-prone NC.
- Ice-and-water shield
- A self-adhering waterproof membrane applied at eaves, valleys, and around penetrations for extra leak protection where water tends to back up or pool.
- Modified bitumen (mod-bit)
- An asphalt-based membrane reinforced with polymers, used on low-slope and flat roofs. Applied in rolls, often on commercial buildings.
- OSB
- Oriented strand board, an engineered wood panel commonly used as roof decking. Like plywood, it must stay dry — wet or delaminated OSB is replaced during a re-roof.
- Pitch (slope)
- How steep a roof is, expressed as rise over run (e.g., 6:12 means 6 inches of rise per 12 inches of horizontal run). Steeper pitches cost more to work on and shed water faster.
- Penetration
- Anything that comes through the roof surface — a vent pipe, chimney, or skylight. Each penetration needs proper flashing to stay watertight.
Glossary · R–Z
Roofing Terms R to Z
- Rafter
- A structural framing member that runs from the ridge down to the eave, supporting the decking and everything above it.
- Rake
- The sloped edge of a roof at a gable end, running from eave to ridge. Rake edges are finished with trim and drip edge.
- Ridge
- The horizontal line at the very top of the roof where two slopes meet. It’s the peak, capped with ridge shingles or a ridge cap.
- Ridge vent
- A vent installed along the ridge that lets hot, humid attic air escape. Paired with soffit vents, it drives the airflow that protects your roof and lowers cooling costs in NC summers.
- Soffit
- The underside of the roof overhang, between the fascia and the wall. Soffit vents pull cool air into the attic to feed ventilation.
- Square
- A roofing unit of measure equal to 100 square feet of roof surface. Roofers price and quantify materials by the square — see our roof cost guide.
- Starter strip
- The first course of shingles (or a purpose-made starter product) installed at the eaves to seal and anchor the shingles above against wind uplift.
- Standing seam
- A metal roofing system with raised, interlocking vertical seams and no exposed fasteners. Sleek, durable, and long-lasting — see metal roofing.
- TPO
- Thermoplastic polyolefin, a single-ply reflective membrane widely used on flat commercial roofs for its energy efficiency and heat-welded seams.
- Underlayment
- The water-resistant layer installed over the decking and beneath the shingles — felt or synthetic — that provides a secondary barrier against water.
- Valley
- The internal angle where two roof slopes meet and channel water down. Valleys carry a lot of runoff, so they’re lined with flashing or membrane and are a common leak point if done poorly.
- Ventilation
- The balanced intake (soffit) and exhaust (ridge) airflow that keeps an attic cool and dry. Good ventilation extends shingle life and helps prevent moisture problems.
Still Have Questions?
Get a Free Roof Inspection & Plain-English Report
We’ll walk your roof, explain what we find without the jargon, and put honest recommendations in writing.
Glossary FAQ
Quick Answers
What is a “square” in roofing?
A square is 100 square feet of roof surface. Roofers measure and price roofs by the square, so a 2,000-square-foot roof is about 20 squares before adding for pitch and waste.
What’s the difference between underlayment and decking?
Decking is the wood surface fastened to the rafters. Underlayment is the water-resistant layer rolled over the decking, beneath the shingles, as a secondary moisture barrier.
Why does flashing matter so much?
Flashing seals the vulnerable joints where the roof plane changes — chimneys, walls, valleys, and skylights. Most roof leaks trace back to failed or missing flashing, not the shingles themselves.
What are TPO and EPDM used for?
Both are membranes for flat and low-slope roofs, common on commercial buildings. TPO is a reflective thermoplastic; EPDM is a rubber membrane. See our commercial roofing page.
FREE, NO-OBLIGATION ESTIMATE
Know Your Roof? Let’s Take Care of It.
Whether you need a repair, a replacement, or just answers, our team is ready to help — no jargon, no pressure.