Roofing Terms, Explained in Plain English

The surface materials that shed water on a sloped roof — the most common vocabulary NEPA homeowners and realtors run into.

Architectural shingle

dimensional shingle · laminated shingle

A fiberglass-mat asphalt shingle cut and laminated into two layers to create a thicker, dimensional profile. The standard replacement shingle on most Northeast PA homes — heavier, more wind-resistant, and longer-lasting than a 3-tab shingle. Owens Corning Duration® and CertainTeed Landmark™ are common examples.

3-tab shingle

A single-layer asphalt shingle cut into tabs to look like individual pieces. The older, lighter, flatter shingle that architectural shingles replaced on most roofs. Still occasionally used on sheds and outbuildings.

Designer shingle

luxury shingle

A premium, heavyweight architectural shingle styled to mimic slate or wood shake. More material and a deeper profile than a standard architectural shingle, with a higher price and longer warranty.

Asphalt shingle

Any shingle built on a fiberglass or organic mat saturated with asphalt and surfaced with mineral granules. Architectural and 3-tab shingles are both asphalt shingles — the most common residential roofing material in the United States.

Granules

The colored ceramic-coated mineral particles embedded in the top surface of an asphalt shingle. Granules block UV light (which dries out the asphalt), give the shingle its color, and add fire and impact resistance. Granule loss in gutters is a sign of an aging or storm-damaged roof.

Roofing square

A unit of roof area equal to 100 square feet. Roofing materials and labor are priced 'per square,' so a 2,200 sq ft roof is 22 squares. One bundle of standard architectural shingles typically covers one-third of a square (three bundles per square).

Pitch

roof slope

The steepness of a roof, expressed as rise over run (inches of height per 12 inches of horizontal distance). A '6/12 pitch' rises 6 inches for every foot it runs. Steeper pitches cost more because they require harnesses, jacks, and slower crew movement, and they have more surface area per square foot of building footprint.

Standing seam metal roofing

A metal roof system where long, continuous panels are joined by raised, interlocking seams fastened with hidden clips — so no exposed screws sit on the roof face. Durable, snow-shedding, and wind-resistant; popular in the Poconos and Back Mountain for lake and hilltop homes.

Stone-coated steel

Steel panels pressed into the shape of shingles or shakes and coated with stone granules. Lighter than asphalt, impact- and wind-rated, and often approved in HOAs that prohibit exposed-metal standing seam.

Slate

Natural stone roofing split into thin, durable tiles. Vermont slate is the standard in Northeast PA — a century-class material on historic Scranton and Honesdale homes. Heavy, expensive, and requires a contractor experienced with slate.

Terra cotta

Fired clay tile roofing — the distinctive barrel or flat tiles common on Mediterranean- and Spanish-style homes. Ludowici is the premium American brand. Heavy and long-lasting like slate, with a high-end price.

Roof rejuvenation

A restorative treatment that penetrates aging asphalt shingles and replaces the oils lost to heat, UV, and age — restoring flexibility and adding 5–15 years of roof life for a fraction of replacement cost. Roof Positive's rejuvenation includes a free roof tune-up that fixes nail pops, flashing, and sealant issues before treatment.

The membrane systems used on flat roofs, porches, additions, and commercial buildings — where shingles don't work because water can't run off fast enough.

TPO

thermoplastic polyolefin · thermoplastic polyolefin membrane

A single-ply white roofing membrane made of thermoplastic polyolefin, heat-welded at the seams to form a continuous, waterproof sheet. TPO is reflective (cools the roof and lowers energy bills), flexible, and common on flat and low-slope commercial and residential roofs.

EPDM

ethylene propylene diene monomer · rubber roof

A durable synthetic rubber roofing membrane (ethylene propylene diene monomer) sold in black or white sheets. EPDM is glued or mechanically fastened at the seams and is the most common flat-roof membrane on older Northeast PA row homes, porches, and additions.

Granulated flat roofing

A self-adhesive, peel-and-stick flat-roof membrane surfaced with mineral granules (like a shingle) for UV protection and walkability. A cleaner, low-odor alternative to torch-down roofing on residential porches and low-slope sections.

Modified bitumen

A multi-ply asphalt flat-roof membrane reinforced with a polyester or fiberglass mat. Often installed with a torch (torch-down) or in self-adhesive peel-and-stick rolls. Heavier and more puncture-resistant than single-ply EPDM or TPO.

Ponding water

Standing water that remains on a flat roof 48 hours after rain. A small amount is normal; persistent ponding indicates poor drainage, sagging, or clogged drains and will shorten the life of any flat-roof membrane.

Low-slope roof

A roof with a pitch under 2/12 (less than 2 inches of rise per foot). Too shallow for shingles, which require at least a 2/12 pitch to shed water — so low-slope roofs use membrane systems like TPO, EPDM, or modified bitumen instead.

The parts that make up a roof — the terms an inspector or roofer uses when describing what's above your head.

Decking

sheathing · roof deck

The structural wood panels (usually OSB or plywood) nailed across the roof rafters. The decking is what shingles and underlayment attach to. Soft or rotted decking discovered during tear-off is replaced before the new roof goes on.

Rafter

The structural wood beams that slope from the ridge to the eaves and carry the roof's weight. The framing underneath the decking.

Ridge

The highest horizontal line where two roof planes meet at the top of the roof.

Hip

The sloped outside corner where two roof planes meet, running from the ridge down to the eave. A 'hip roof' slopes on all four sides with no vertical walls.

Valley

The inside angle where two roof planes slope down and meet — a natural channel for water, and the most leak-prone spot on a roof. Valleys are flashed and often lined with ice and water shield.

Gable

The triangular vertical wall section at the end of a pitched roof. A 'gable roof' has two sloping planes and vertical gable walls at each end.

Eave

The lower edge of the roof that overhangs the exterior wall. Where gutters hang.

Rake

The sloped outside edge of a gable roof — the trim line that runs from eave to ridge along the gable wall.

Fascia

The vertical board running along the lower edge of the roof, just behind the gutters. The fascia caps the rafter tails and is what gutter brackets attach to.

Soffit

The horizontal underside of the eave overhang. Soffit vents are the intake vents that pull fresh air into the attic for ventilation.

The hidden layers and metal details that keep water out at the seams, edges, and penetrations where a shingle alone isn't enough.

Underlayment

The water-resistant sheet (felt or synthetic) rolled across the decking before the shingles go on. Underlayment is the backup waterproofing layer that protects the deck if shingles blow off or leak — especially during wind-driven rain.

Ice and water shield

A self-adhering, waterproof membrane (typically modified bitumen) stuck directly to the decking at the eaves, valleys, and penetrations. It seals around nail holes to prevent ice-dam backups from leaking in. Building code in cold climates like Northeast PA requires it at least 24 inches inside the exterior wall.

Synthetic underlayment

A lightweight, tear-resistant woven polypropylene underlayment that replaces old felt paper. Lighter, stronger, and more UV-stable than #15 or #30 felt — the standard underlayment on modern shingle roofs.

Drip edge

An L-shaped metal flashing installed along the eaves and rakes. Drip edge directs water off the roof edge and away from the fascia so water doesn't curl back under the shingles and rot the decking.

Flashing

Thin metal (aluminum, galvanized steel, or copper) installed where the roof meets a wall, chimney, skylight, or vent to direct water away from the seam. Flashing failures are one of the most common causes of roof leaks.

Step flashing

Short, overlapping rectangular metal flashing pieces installed in a 'stair-step' pattern where a sloped roof meets a vertical wall. Each piece interweaves with a course of shingles so water shed down the wall runs onto the roof, not under it.

Kickout flashing

A small angled flashing at the lower end of a roof-to-wall intersection that kicks water out and away from the wall. Missing kickout flashing is a leading cause of water intrusion behind siding — and a common find on older NEPA additions.

Chimney flashing

The combination of base, step, and counter flashing that seals the joint between a chimney and the roof. Often rebuilt when a roof is replaced, since the old flashing rarely fits the new shingle profile.

Valley flashing

The metal or membrane lining that waterproofs a roof valley — where two roof planes meet and concentrate water flow. W- or V-shaped metal valleys are common in heavy-snow regions like the Poconos.

Pipe boot

pipe flashing · plumbing vent flashing

The rubber or metal flashing that seals the gap around a plumbing vent pipe penetrating the roof. Rubber boots crack and split with age (a top leak source on older roofs) and are replaced during a roof replacement.

Dormer

A small roofed projection — usually with a window — that breaks out of a sloped roof plane. Dormers add light and headroom upstairs but add complexity, seams, and flashing that a simple roof doesn't have.

Curb

The raised wood frame a skylight or roof hatch sits on. Curbs are flashed on all four sides where they meet the roof.

Balanced airflow through the attic is what keeps shingles cool, prevents ice dams, and stops moisture damage — and it's part of every Roof Positive inspection.

Ridge vent

A continuous vent installed along the roof ridge (the peak) that lets hot, moist air escape the attic. Paired with soffit intake vents to create balanced airflow from eave to ridge.

Soffit vent

Intake vents in the soffit (the underside of the eave) that draw cool, dry outside air into the attic. Soffit vents are the intake half of a balanced ventilation system; without them, a ridge vent can't pull air.

Roof ventilation

The balanced intake-and-exhaust airflow that moves air through the attic. Proper ventilation extends shingle life, lowers attic temperature, reduces moisture, and helps prevent ice dams in winter.

Ice dam

A ridge of ice that forms at the roof eave when a warm attic melts snow, the meltwater runs down and refreezes at the cold edge. The ice traps water behind it, forcing meltwater under the shingles and into the home. Prevented with proper attic insulation, ventilation, and ice and water shield at the eaves — all standard on Roof Positive installs.

Box vent

static roof vent · low-profile vent

A small square off-ridge exhaust vent used when a ridge vent isn't possible — for example on a hip roof with very little ridge length. Roof Positive installs box vents to balance ventilation where needed.

Power attic vent

A motorized roof or gable fan that actively exhausts attic air. Used when passive ridge-and-soffit ventilation can't keep up, especially on tight, low-pitch roofs.

How the roof sheds water off the edge and away from the foundation.

Seamless gutter

A gutter formed on-site from a single continuous coil of aluminum — no mid-run seams to leak. The standard for replacement gutters; cut to the exact length of each roof edge.

Downspout

The vertical pipe that carries water from the gutters down to the ground and away from the foundation. Downspouts should discharge at least 4–6 feet from the foundation wall.

Gutter guard

leaf guard · gutter protection

A screen, mesh, or solid-cover system installed over gutters to keep leaves and debris out while letting water in. Reduces cleaning and prevents clog-related overflow that can rot fascia and flood landscaping.

Gutter apron

A length of L-shaped flashing tucked under the first course of shingles and over the back of the gutter. It directs water off the roof edge and into the gutter instead of running behind it onto the fascia.

Drip edge flashing

The metal edge flashing along the eaves and rakes that keeps water from wicking back under the shingles and rotting the decking — installed before underlayment and gutters.

The terms that show up in a roof inspection report or an insurance claim — what's actually wrong with the roof.

Nail pop

A roofing nail that has lifted or backed out of the decking, pushing the shingle above it up into a visible bump. Caused by wood movement, freeze-thaw cycling, or undersized fasteners. Nail pops are fixed during a roof tune-up before they wear through the shingle.

Curling shingle

An asphalt shingle whose tabs or edges have lifted and curled up — a sign the shingle has dried out and lost flexibility. Curling shingles catch wind and eventually blow off; it's a primary indicator a roof is aging toward replacement, or a candidate for rejuvenation if caught early.

Cupping shingle

A shingle that has bowed into a cup shape — the center sinks and the edges lift. Like curling, cupping signals asphalt that has lost its oils and is becoming brittle.

Blistering

Small bubbles or raised spots in a shingle where trapped moisture or manufacturing gases expanded under heat. Mostly cosmetic unless the blisters break open and expose the fiberglass mat.

Hail damage

Impact damage from hail — visible as dark, granule-loss bruises or divots in shingles, and dents in metal flashing, gutters, and vents. Hail bruising shortens roof life and is often covered by homeowners insurance; Roof Positive documents hail damage for your claim as a former insurance adjuster.

Wind damage

Shingles lifted, creased, or torn off by wind — visible as creased horizontal lines across tabs or bare patches where shingles blew away. Wind-rated shingles and proper fastener patterns resist wind uplift; Roof Positive inspects and documents wind damage for insurance claims.

Tear-off

Removing the existing roof layers down to the decking before installing a new roof. A full tear-off exposes the decking for inspection and repair, and is the only way to install a warranty-backed roof over an old one. The number of existing layers (1–3) affects tear-off cost and time.

Layering

Installing a new roof directly over an existing one without tearing it off (a 'roof-over'). Building code allows at most one roof-over (two total layers). Roof Positive generally recommends a full tear-off so the decking can be inspected and the warranty is valid.

Roof tune-up

A pre-rejuvenation repair pass that fixes nail pops, re-seals flashing and pipe boots, and addresses loose or lifted shingles before a rejuvenation treatment is applied. Included free with every Roof Positive roof rejuvenation.

Algae

Dark streaks on a roof caused by Gloeocapsa magma, a blue-green algae that feeds on the limestone filler in asphalt shingles. Cosmetic but common on humid, shaded NEPA roofs; some shingles are algae-resistant (AR).

Moss

A root-like plant that holds moisture against the shingle surface, accelerating wear. Moss should be gently removed (never power-washed) and treated; it thrives on shaded, damp, north-facing roofs.