Roofing Glossary

A-Frame Roof

A steep roof whose two planes run down to or near the foundation, so the roof also forms the main walls.

Actual Cash Value

Actual cash value (ACV) is the way a homeowners policy values damaged property at what it was worth just before the loss: the cost to replace it today minus depreciation for its age and condition.

Aluminum Roofing

Metal roofing made from aluminum, which does not rust and is lighter than steel, so it is common near salt water.

Architectural Shingles

Architectural shingles are asphalt roof shingles made from two or more layers bonded together, so each shingle is thicker than a flat strip shingle and gives the roof a textured, three-dimensional look.

Asphalt Shingles

Asphalt shingles are roofing pieces made from a fiberglass mat coated with asphalt and topped with mineral granules, laid in overlapping rows so water runs off the roof.

Attic Ventilation: see Roof Ventilation

Box Vent

A static exhaust vent: a low square hood cut into the roof near the ridge. Several are usually needed to match one run of ridge vent.

Butterfly Roof

A roof made of two planes that slope down toward a central valley, forming a V. All the water drains to the middle.

Chimney Flashing

Chimney flashing is the set of metal pieces that seal the joint where a chimney passes through a roof: an apron on the downhill side, step flashing up both sides, a cricket or back pan on the uphill side, and counterflashing set into the masonry that laps over all of them.

Clay Tile Roofing

Clay tile roofing is a roof covering made of tiles shaped from natural clay and fired in a kiln, laid in overlapping rows over a solid deck and a waterproof underlayment.

Composite Roofing

Composite roofing is a roof covering made of molded tiles or shingles from plastic polymers, rubber, or blends of the two, shaped to look like natural slate or cedar shake.

Concrete Tile Roofing

Roof tiles cast from sand, cement and water, often colored to look like clay. They are heavy and need a frame rated for the load.

Copper Roofing

Metal roofing made from copper, which weathers from bright metal to brown and eventually a green patina.

Corrugated Metal Roofing

Metal roofing panels formed into repeating waves or ribs and fastened with exposed screws through the panel face.

Cost per Roofing Square: see Roofing Square

Cost per Square Foot: see Roofing Square

Counterflashing

Metal flashing set into or over a wall or chimney that laps down over the base or step flashing, so water cannot get behind it.

Drip Edge

Drip edge is a strip of bent metal flashing installed along a roof's eaves and rake edges that carries water off the edge of the roof and away from the fascia and the deck beneath.

Drone Roof Inspection

A roof inspection using photos or video from a drone. In the US the pilot needs an FAA Part 107 certificate for commercial work.

Emergency Roof Repair

Temporary work to stop water getting in after damage, such as tarping or sealing, before a permanent repair.

Exhaust Vent

Any vent high on the roof, such as a ridge vent or box vent, that lets warm, moist air out of the attic.

Flat Roof: see Low-Slope Roof

Full Roof Replacement

Replacing the covering on every plane of the roof, as opposed to a section.

Gable Roof

A roof with two planes sloping down from a central ridge, leaving a triangular wall (the gable) at each end.

Gable Vent

A louvered opening in the gable wall of an attic. Mixed with ridge vents, it can short-circuit airflow.

Gambrel Roof

A two-sided roof with two slopes on each side, a shallow upper slope and a steep lower one, as on a traditional barn.

Hail Damage

Roof damage from hailstones: bruised or cracked shingles, dislodged granules, dented metal, broken tile.

Hail Damage Insurance Claim

A homeowners claim for hail damage to a roof, often subject to a separate wind/hail deductible.

Hail-Resistant Roofing: see Impact-Resistant Shingles

Hip Roof

A roof whose planes slope down to every wall, so it has no vertical gable ends. The sloped external corners are called hips.

Hurricane Roofing

Hurricane roofing is a roof built to stay on and keep water out in hurricane-force wind, using a sealed roof deck, stronger deck nailing, wind-rated coverings and tightly fastened edges.

Ice and Water Shield

Ice and water shield is a self-adhering, rubberized asphalt membrane laid directly on the roof deck under the roof covering, where it seals around nails and blocks water that ice dams or wind-driven rain push back under the shingles.

Ice Dam

A ridge of ice at the eaves that traps meltwater behind it on the roof, which can back up under the shingles.

Impact-Resistant Shingles

Impact-resistant shingles are roof shingles that have passed a lab test in which steel balls or ice balls strike the shingle, and earned an impact class from 1 to 4, with Class 4 the highest.

Infrared Roof Inspection: see Roof Moisture Inspection

Insurance Adjuster

An insurance adjuster is the person who inspects damage after a claim, decides what the policy covers and estimates what it will cost to repair or replace.

Insurance Deductible

An insurance deductible is the part of a covered claim that you pay yourself before your homeowners policy pays the rest.

Intake Vent

Any vent low on the roof, usually in the soffit or at the eave, that lets outside air into the attic.

Kickout Flashing

Kickout flashing is a small angled piece of metal or molded plastic set at the bottom of a roof-to-wall joint, where the roof edge stops but the wall keeps going down, that turns the water running along the wall out into the gutter instead of letting it pour down and into the wall.

Low-Slope Roof

A low-slope roof, often called a flat roof, is a roof with only a slight fall, usually less than 2 inches of rise per foot, so it needs a sealed covering such as a membrane instead of overlapping shingles.

Luxury Asphalt Shingles

A heavier, thicker tier of laminated asphalt shingle made to look like slate or wood shake. "Luxury" and "designer" are marketing names, not a standard.

Mansard Roof

A four-sided roof with two slopes on every side, the lower slope steep and often pierced by dormers, the upper slope shallow.

Manufacturer Warranty

A manufacturer warranty is the shingle maker's written promise to repair, replace or pay toward its products if they fail from a manufacturing defect within a set period.

Metal Roofing

Metal roofing is a roof covering made of metal sheets, panels or shingles, most often steel, aluminum, copper or zinc, fastened to the roof deck to shed water, snow and sun.

Partial Roof Replacement

Replacing the covering on part of a roof. Matching color and age to the rest is the usual problem.

Pipe Flashing

Pipe flashing, often called a roof boot, is a flat flashing plate with a raised collar that slides over a plumbing vent pipe where it comes through the roof, so the plate sheds water onto the shingles and the collar seals tight around the pipe.

Powered Attic Vent

An electric fan that exhausts attic air. It can pull conditioned air from the house through ceiling gaps if intake is short.

Recoverable Depreciation

Recoverable depreciation is the part of a replacement cost claim that the insurer holds back at first and pays later, once the damaged property has been repaired or replaced and you send proof of the cost.

Remaining Roof Life: see Roof Life Expectancy

Replacement Cost Value

Replacement cost value (RCV) is what it would take to repair or replace damaged property with materials of similar kind and quality at today's prices, without subtracting depreciation for age or wear.

Reroofing

Reroofing is the work of putting a new roof covering on a house that already has one, either by tearing the old covering off down to the deck (a replacement) or by laying the new covering over the old one (a recover, often called an overlay).

Ridge Cap

A ridge cap is the row of shingles bent over the peak of a roof, and over its hips, to seal the joint where two roof planes meet.

Ridge Vent

A ridge vent is a long, low exhaust vent that runs along the peak of a sloped roof, covering a slot cut in the roof deck so warm, damp attic air can escape at the highest point.

Roof Algae

Dark streaks on a roof, usually the cyanobacterium Gloeocapsa magma. It is mostly cosmetic; algae-resistant shingles carry copper granules.

Roof Assembly: see Roofing System

Roof Blistering

Raised bubbles in shingles or a membrane where trapped moisture or gas lifts the surface. Blisters that break expose the material below.

Roof Boot: see Pipe Flashing

Roof Buckling

Shingles that ripple or lift in lines, often from a deck or underlayment that moved or was installed wet.

Roof Certification

A roof certification is a signed document from a qualified roofer or inspector stating that a roof is in sound condition on the day of inspection and estimating how many years of useful life it has left.

Roof Claim Documentation

The evidence for a roof claim: dated photos, the inspection report, the contractor estimate and the insurer's paperwork.

Roof Condensation

Moisture from inside the house condensing on the cold underside of the roof deck, usually from poor ventilation or air leaks.

Roof Condition Assessment: see Roof Inspection Report

Roof Covering

The weather-shedding top layer of a roof, such as shingles, tile, metal panels or a membrane. Building codes use "roof covering" for this layer.

Roof Cracking

Splits in shingles, tiles or a membrane from age, thermal movement or impact. Cracks let water reach the layer below.

Roof Curling

Shingle edges that turn up (cupping) or tabs that arch (clawing), a sign of age, heat or poor attic ventilation.

Roof Damage Assessment

An inspection focused on documenting damage from an event, such as hail or wind, usually for an insurance claim.

Roof Damage Insurance

Homeowners insurance coverage for sudden roof damage. Wear, age and lack of maintenance are generally not covered.

Roof Deck: see Roof Sheathing

Roof Eave

The lower edge of a roof plane, where it overhangs the wall. Drip edge, gutters and, in cold climates, the ice barrier are all installed at the eave.

Roof Edge

Any perimeter of a roof plane: the eave along the bottom, the rake along a gable end, or the edge where a low-slope roof meets a parapet.

Roof Estimate

A roof estimate is a roofer's written statement of what work they will do on your roof, with what materials, and at what price, usually broken into line items such as squares of roofing, tear-off, deck repair, flashing, permits and warranty terms.

Roof Fasteners: see Roofing Nails

Roof Flashing

Roof flashing is thin, water-shedding material, usually bent metal, installed at the joints of a roof where shingles alone cannot keep water out: along walls, around chimneys and pipes, in valleys and at the roof edges.

Roof Granule Loss

Asphalt shingles shedding their mineral granules. Some loss after installation is normal; bald patches expose asphalt to sunlight.

Roof Inspection

A check of the covering, flashing, penetrations, ventilation and attic to report the roof's condition and any damage.

Roof Inspection Report

A roof inspection report is the written record of a roof inspection: what parts of the roof were looked at, how they were looked at, what defects were found, photos of those defects, and what the inspector recommends doing next.

Roof Installation Cost

The price of installing a roof covering, which a quote splits into materials, labor, disposal and permits.

Roof Insurance Claim

A claim on a homeowners policy for roof damage from a covered event such as wind or hail.

Roof Leak

Water getting past the roof covering into the deck, attic or house. Most leaks start at flashing, penetrations or damaged shingles, not open field.

Roof Leak Detection

Finding where water enters a roof, by visual inspection, water testing or moisture-sensing methods such as infrared scanning.

Roof Life Expectancy

Roof life expectancy is the number of years a roof covering is expected to keep the weather out under normal conditions, before it needs replacing.

Roof Moisture Inspection

A roof moisture inspection is a survey that finds water trapped inside a roof, usually in the insulation under a flat or low-slope membrane, using infrared cameras, electrical impedance scanners or nuclear gauges, then confirms the readings with small core cuts.

Roof Mold

Mold growing on the attic side of the deck or framing, usually from condensation or a leak. Fix the moisture source first.

Roof Moss

Moss growing on a shaded, damp roof. It holds water against the covering and can lift shingles as it grows.

Roof Overhang

The part of a roof that projects past the wall below it, at the eaves or the rakes. Overhangs shed water away from the siding and windows.

Roof Overlay: see Reroofing

Roof Pitch

Roof pitch is the steepness of a roof, written as the inches it rises for every 12 inches it runs horizontally, so a 6/12 roof climbs 6 inches per foot.

Roof Plane

One flat, continuous sloped surface of a roof. A simple gable roof has two planes; measurement reports add up the area of every plane.

Roof Ponding

Roof ponding is water that collects in low spots on a roof and is still there more than 48 hours after the rain stops, in weather that would normally dry it, which is the line the roofing trade uses to tell a real drainage problem from a puddle that is just slow to dry.

Roof Puncture

A hole through the roof covering from a falling branch, foot traffic, a tool or hail.

Roof Rafter

A sloped framing member that runs from the ridge to the wall and supports the roof deck. Rafters are cut and assembled on site, unlike trusses.

Roof Repair

Fixing a defined part of a roof, such as a leak, flashing or a damaged section, without replacing the whole covering.

Roof Repair Cost

The price of a roof repair, driven by access, materials and how much hidden damage is found.

Roof Replacement

Removing the old roof covering (or recovering it, where allowed) and installing a new one over the whole roof.

Roof Replacement Cost

The price of replacing a roof, driven by size, pitch, material, tear-off layers and deck repair.

Roof Replacement Process

The steps of a reroof: inspection and quote, permit, tear-off, deck repair, underlayment, flashing, covering, cleanup and final inspection.

Roof Replacement Signs

Signs a roof may be near the end of its life: age, widespread granule loss, curling, repeated leaks and deck damage.

Roof Replacement Timeline

How long a reroof takes from quote to final inspection. The roofing itself is often one to three days on a house; permits and weather add time.

Roof Ridge

The horizontal line at the top of a roof where two planes meet. It is capped with ridge shingles and is the usual place for a ridge vent.

Roof Rot

Decay in the wooden deck, fascia or framing after long exposure to moisture. Rotten deck must be replaced before new roofing goes on.

Roof Sagging

A visible dip in a roof line or plane. It can mean a wet or failed deck or a structural problem and needs a professional look.

Roof Sheathing

Roof sheathing is the layer of plywood, OSB or wood boards nailed across the rafters or trusses.

Roof Slope: see Roof Pitch

Roof Structure

The framing that holds a roof up: rafters or trusses, ridge board, ceiling joists and bracing. The roof deck and covering sit on top of it.

Roof Tarp

A heavy waterproof sheet fastened over a damaged area to keep water out until it is repaired.

Roof Tear-Off: see Reroofing

Roof Truss

A roof truss is a frame of wood pieces joined into a set of triangles, usually in a factory, that holds up a roof.

Roof Underlayment

Roof underlayment is a sheet laid over the whole roof deck before the shingles or other roof covering go on.

Roof Vent: see Roof Ventilation

Roof Ventilation

Roof ventilation is the system of vents that lets outside air enter an attic low, near the eaves, and leave high, near the ridge, so heat and moisture do not build up under the roof deck.

Roof Warranty

A roof warranty is a written promise to repair or pay for certain roof failures for a set time.

Roof Wind Uplift

Roof wind uplift is the upward pull that wind puts on a roof as it flows over and around a building, lifting shingles, panels or the whole deck away from the framing below.

Roofing Contractor

A business that installs and repairs roofs. Licensing, insurance and warranty terms vary by state and company.

Roofing Contractor License

State or local permission to do roofing work for pay. Requirements vary widely; some states license roofers and some do not.

Roofing Cost

What roofing work costs. Our cost guide gives sourced, dated figures; this glossary does not quote prices.

Roofing Felt

Asphalt-saturated underlayment sold by weight, commonly No. 15 or No. 30, laid over the deck before the roof covering.

Roofing Labor Cost

The labor share of a roofing quote, driven by pitch, height, complexity and local wages.

Roofing Material Cost

The materials share of a roofing quote: covering, underlayment, flashing, vents and fasteners.

Roofing Nails

Roofing nails are short nails with a wide, flat head that hold shingles to the roof deck.

Roofing Screws

Gasketed screws used to fasten exposed-fastener metal panels. The rubber washer seals the hole and wears out over time.

Roofing Square

A roofing square is a unit of area equal to 100 square feet of roof surface, a 10-by-10-foot patch, and it is the unit in which shingles are sold and most roofing quotes are priced.

Roofing System

A roofing system is all the parts of a roof that work together to keep water and weather out of a house.

Shed Roof

A roof with a single plane sloping in one direction, often used on additions, porches and modern houses. Also called a skillion roof.

Skillion Roof

The Australian name for a shed roof: one plane sloping in a single direction.

Slate Roofing

Slate roofing is a roof covering made of thin pieces of natural stone, split from quarried slate rock and nailed to a solid roof deck in overlapping rows.

Soffit Vent

A soffit vent is an opening in the underside of a roof's overhang, the soffit, that lets outside air flow into the attic so it can sweep up under the roof deck and leave through exhaust vents near the peak.

Solar Shingles

Solar shingles are roof shingles or tiles with built-in solar cells, so the same pieces that shed rain also turn sunlight into electricity.

Standing Seam Metal Roof

A standing seam metal roof is a metal roof made of long panels whose edges rise up and join in raised seams, with hidden clips under the seams holding the panels to the roof deck, so no screw passes through the flat part that carries water.

Step Flashing

Step flashing is a set of small, L-shaped pieces of metal, one for each row of shingles, woven into the roof where a sloped roof runs up beside a wall, a dormer or a chimney side, so water on the roof is sent back onto the shingles and away from the wall.

Storm Damage

Roof damage from a storm event, including hail, wind and falling trees. It is the usual trigger for a homeowners insurance claim.

Synthetic Roofing: see Composite Roofing

Synthetic Slate Roofing

Roofing tiles molded from polymers or rubber blends to look like natural slate at a fraction of its weight.

Synthetic Underlayment

A woven or spun polymer underlayment, lighter and more tear-resistant than felt, laid over the deck before the roof covering.

Turbine Vent

An exhaust vent with a wind-driven spinning head that pulls air out of the attic.

Valley Flashing

Valley flashing is the lining installed in a roof valley, the inside corner where two roof slopes meet, so the water both slopes send into that one line runs down to the eave instead of into the deck.

Wind Damage

Roof damage from high wind: lifted, creased or missing shingles, torn-off ridge caps and edges, debris impact.

Wind Damage Insurance Claim

A homeowners claim for wind damage to a roof, often subject to a separate wind/hail deductible.

Wind-Resistant Roofing: see Roof Wind Uplift

Wood Shakes

Wood shakes are thick roof pieces split or sawn from logs, most often cedar, nailed in overlapping rows; wood shingles are their thinner, smoothly sawn cousins.

Wood Shingles: see Wood Shakes

Workmanship Warranty: see Roof Warranty

Zinc Roofing

Metal roofing made from zinc, which forms its own protective surface layer as it weathers to a matte grey.