Updated March 2026

Roofing Glossary

Roofers throw around a lot of terms. Most of them are not complicated once someone explains them in plain English. That is what this page is for.

Bookmark it. Pull it up when you are reading an estimate or talking to a contractor. If a word is not here, they might be making it up.

A B C D E F G H I J L N O P R S T U V W

A

Architectural Shingles

The most popular shingle on the market right now. They are thicker than 3-tab shingles, have a dimensional look, and last 25-30 years. Most roof replacements today use architectural shingles. Expect to pay $4.50-$8.00 per square foot installed.

Asphalt Shingles

The most common roofing material in America. Made from fiberglass mat coated with asphalt and covered with granules. They come in two main types: 3-tab and architectural. See our full breakdown of shingle roof costs.

Attic Ventilation

The system of vents that lets air flow through your attic. Good ventilation prevents heat buildup in summer and moisture problems in winter. Most roofs use a combo of soffit vents (air in) and ridge vents (air out).

B

Box Vent

A square or round vent that sits on top of your roof and lets hot air escape from the attic. They are the older style. Most new roofs use a ridge vent instead because it provides more even ventilation across the whole roof.

C

Chimney Flashing

The metal pieces that seal the gap where your chimney meets the roof. Bad chimney flashing is one of the most common leak sources. If your roofer is up there anyway, ask them to check it. Replacing chimney flashing usually costs $300-$600.

Cricket (Chimney Diverter)

A small peaked structure built behind a chimney to divert water around it. Without a cricket, water pools behind the chimney and eventually leaks. Building code requires one if your chimney is wider than 30 inches.

D

Deck (Roof Deck)

The plywood or OSB boards that make up the structural surface of your roof. Everything else sits on top of the deck. If your deck has water damage or rot, your roofer needs to replace those sections before installing new shingles. That costs extra.

Dormer

A window that sticks out from the roof slope. Dormers add complexity to your roof because they create extra edges, flashing points, and valleys. More dormers means higher labor costs on a replacement.

Downspout

The vertical pipe that carries water from your gutter down to the ground. Not technically part of the roof, but your roofer may need to remove and reinstall them during a roof replacement.

Drip Edge

A metal strip installed along the edges of your roof that directs water away from the fascia and into the gutter. Most building codes require it. If your old roof does not have drip edge, your roofer should add it.

E

Eave

The bottom edge of your roof that hangs past the wall. This is where your gutters attach. The soffit is the underside of the eave. Ice and water shield gets installed here to protect against ice dams.

EPDM

Stands for Ethylene Propylene Diene Monomer. It is a black rubber membrane used on flat roofs. Durable and affordable. Been around for decades. Not as reflective as TPO, so it absorbs more heat.

Exposure

The part of the shingle that is visible after installation. On a standard asphalt shingle, about 5 inches is exposed and the rest is covered by the shingle above it. Proper exposure is important for weather protection and warranty compliance.

F

Fascia

The board that runs along the lower edge of your roof. Your gutter attaches to it. If the fascia is rotted, your roofer should replace it before installing new drip edge. Fascia replacement typically costs $6-$20 per linear foot.

Flashing

Thin metal strips installed around chimneys, vents, and edges to prevent water from seeping into joints. Flashing problems are the number one cause of roof leaks. Good roofers replace all flashing during a full replacement.

G

Gable

The triangular section of wall between two sloping roof edges. A gable roof is the classic house shape you drew as a kid. Simple gable roofs are cheaper to replace because they have fewer angles and valleys than a hip roof.

Granules

The tiny colored ceramic pieces embedded on the surface of asphalt shingles. They protect the shingle from UV damage and give it its color. If you see a lot of granules in your gutters, your shingles are aging and it may be time to consider a replacement.

Gutter

The channel along the eave that collects rainwater and sends it to the downspouts. Your roofer may need to remove and reinstall gutters during a roof replacement. Some roofers include this in the quote. Some charge extra. Ask.

H

Hip Roof

A roof where all four sides slope down to the walls. No gable ends. Hip roofs are more wind-resistant but cost more to replace because they have more ridges, valleys, and angles. Expect 10-15% more labor compared to a simple gable roof.

I

Ice and Water Shield

A sticky, rubberized membrane applied to vulnerable areas like valleys and eaves. It self-seals around nail holes. Building codes in cold climates require it on the first 3-6 feet of roof from the eave. Worth having even in the South.

Ice Dam

A ridge of ice that forms at the edge of your roof and prevents melting snow from draining. Water backs up behind the dam and can leak into your home. Proper attic ventilation and ice and water shield help prevent them.

J

Joist

A horizontal structural member that supports the ceiling below the attic. Joists are different from rafters (which are angled and support the roof itself). Your roofer should not need to touch your joists unless there is serious structural damage.

L

Lean-to

A roof with a single slope that leans against a taller wall. Common on additions, porches, and sheds. Simple to roof because there is only one slope and no ridge. A lean-to section on your house adds some complexity to a full replacement but not much.

Low-slope

A roof with a pitch of 2/12 to 4/12. Not flat, but not steep enough for standard shingles without special installation. Low-slope roofs may need modified underlayment or a membrane system. They are common on ranch homes and modern builds.

N

Nail Pattern

The number and placement of nails in each shingle. Standard is 4 nails per shingle. High-wind zones require 6 nails. This matters for your warranty. If the roofer skimps on nails, the manufacturer can void their warranty on your roof.

Nail Pop

When a nail works its way back out of the deck and pushes up through the shingle. You can sometimes see small bumps on the roof surface. One or two nail pops are a simple repair. Lots of them may signal a bigger problem with the deck or installation.

O

OSB (Oriented Strand Board)

An engineered wood panel used for roof decking. It is cheaper than plywood and used on most new construction. OSB holds up fine if it stays dry, but it swells more than plywood when it gets wet. If your roofer finds wet OSB, they need to replace it.

Overhang

How far your roof extends past the exterior wall. The overhang protects your siding and foundation from rain. Typical overhangs are 12-18 inches. The soffit covers the underside of the overhang.

P

Penetration

Any place something goes through the roof surface. Vent pipes, chimneys, skylights, satellite dishes. Every penetration is a potential leak point that needs flashing or a pipe boot. More penetrations mean more labor and more places things can go wrong.

Pipe Boot

A rubber or metal cover that seals around plumbing vent pipes where they come through the roof. Pipe boots dry out and crack after 10-15 years. A cracked pipe boot is one of the most common and cheapest roof repairs ($150-$300).

Pitch

How steep your roof is. Measured as the rise over a 12-inch run. A 6/12 pitch rises 6 inches for every 12 inches of horizontal distance. Steeper roofs cost more to work on because crews need safety gear and move slower. See how pitch affects your cost per square foot.

Plywood

Sheets of layered wood used for roof decking. Stronger and more water-resistant than OSB, but costs more. Older homes usually have plywood decking. If a sheet needs replacing during your reroof, expect to pay $75-$125 per sheet installed.

R

Rafter

The angled structural beams that support your roof from the ridge down to the eaves. Rafters are the bones of your roof. They are stick-built on site, unlike trusses which are pre-made in a factory. Most older homes have rafters.

Rake

The sloped edge of your roof along the gable end. Think of it as the diagonal edge on the side of your house. Drip edge gets installed along the rake to keep water from running down the side of your home.

Ridge Vent

A vent installed along the peak of the roof that lets hot air escape from the attic. It runs the full length of the ridge and is covered by ridge cap shingles so you barely see it. Ridge vents plus soffit vents create the best ventilation system.

R-value

A measure of how well a material resists heat flow. Higher R-value means better insulation. This matters more for your attic insulation than your roofing material, but some metal and tile roofs offer better R-values than asphalt shingles.

S

Sheathing

Another word for roof decking. The plywood or OSB sheets nailed to the rafters or trusses. Everything else sits on top of the sheathing. If yours is rotted, it has to be replaced before new shingles go on.

Slope

Same as pitch. How steep your roof is. Roofers use both words. A low-slope roof is nearly flat. A steep-slope roof is the kind you would not want to walk on. Steeper slope means higher labor costs.

Soffit

The underside of the roof overhang. Soffit vents are small perforated panels that let air into the attic. Good attic ventilation depends on air flowing in through the soffits and out through the ridge vent.

Square

A roofing square is 100 square feet of roof area. Roofers price materials and labor by the square because it makes the math simpler. A typical home has 20-30 squares. When a roofer says your roof is "24 squares," that means 2,400 square feet of roof area.

Starter Strip

A row of shingles installed along the eaves before the main shingles go on. The starter strip provides a seal against wind uplift at the most vulnerable edge of the roof. Skipping it is a code violation and a warranty killer.

Step Flashing

L-shaped pieces of metal woven into the shingles where the roof meets a vertical wall (like a dormer or a second story). Each piece overlaps the one below it like stairs. Bad step flashing is a common leak source that your roofer should replace during a reroof.

T

Tab

The exposed, visible portion of a shingle. 3-tab shingles are called that because each shingle strip has three tabs cut into it, giving the roof a flat, uniform look. Architectural shingles do not have defined tabs.

Tear-off

Removing the old roofing material down to the deck before installing a new roof. Most replacements require a tear-off. It costs $1-$2 per square foot and is where some roofers pad the quote. A dumpster runs $400-$600. Labor is 2-4 hours for a crew of four.

3-Tab Shingles

The cheapest and simplest type of asphalt shingle. Flat, uniform look. They last 15-20 years and cost $3.50-$6.00 per square foot installed. Most manufacturers are phasing them out in favor of architectural shingles. See our full shingle cost breakdown.

TPO

Stands for Thermoplastic Polyolefin. A white rubber membrane used on flat roofs. Reflects heat and is energy efficient. TPO has become the most popular flat roofing material because it is cheaper than PVC and more reflective than EPDM.

Truss

A pre-manufactured triangular frame that supports the roof. Trusses are built in a factory and delivered to the job site. They are faster to install than stick-built rafters and used on most new construction. You should never cut or modify a truss without an engineer.

U

Underlayment

A waterproof layer installed between the roof deck and the shingles. It acts as a backup barrier against leaks. Synthetic underlayment has mostly replaced old felt paper. Your roofer should install it on the entire roof, not just in spots.

V

Valley

The V-shaped channel where two roof slopes meet. Valleys handle a lot of water runoff and need extra protection. Your roofer should install ice and water shield in every valley plus metal flashing or a woven shingle pattern.

W

Warranty

Roofing warranties come in two types. The manufacturer warranty covers material defects (usually 25-50 years). The workmanship warranty covers installation errors by the roofer (usually 5-15 years). Get both in writing. A 50-year shingle warranty means nothing if the roofer installed it wrong. See our roof replacement checklist to make sure you get both.

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