3-Tab Shingles
Flat, single-layer shingles with cutout tabs — the traditional budget option.
Roofing Glossary
Roofing Glossary
Plain-English definitions of the roofing terms you will hear from contractors, adjusters, and inspectors — written for Maryland homeowners, whether you hire us or not.
Algae Streaking (Gloeocapsa Magma)
Black streaks on shingles caused by an airborne blue-green algae.
Alligatoring
A pattern of interconnecting surface cracks resembling alligator skin.
Apron Flashing
The wide metal piece flashing the uphill side of a chimney or curb.
Architectural Shingles
Multi-layer dimensional shingles — the most popular residential roofing choice.
ASTM D7158
The standard laboratory test for shingle wind uplift resistance.
Attic Air Sealing
Sealing the gaps and penetrations that leak conditioned air into the attic.
Attic Condensation
Moisture that forms when warm, humid air contacts the cold underside of the roof.
Balanced Ventilation
An attic system where intake airflow matches exhaust airflow.
Bird Stop
Shaped closures that seal the eave gaps on tile, metal, or shake roofs.
Box Vent (Static Vent)
A square, static exhaust vent installed near the roof's peak.
California (Long Island) Valley
A valley where one slope's shingles run through and the other side butts into them.
Cedar Shake Roofing
Hand-split wooden shingles with a thick, rustic profile.
Chimney Flashing
The multi-part metal system sealing the joint between chimney and roof.
Clay Tile Roofing
Fired-clay roofing tiles with distinctive barrel or flat profiles.
Closed (Closed-Cut) Valley
A valley with shingles run across it and cut in a straight line for a seamless look.
Collar Tie
Horizontal boards connecting opposing rafters high near the peak.
Cool Roof
Roofing designed to reflect sunlight and stay cooler than standard roofs.
Coping
The watertight cap covering the top of a parapet wall.
Counter Flashing
The outer metal layer that caps and protects base flashing at chimneys and walls.
Dead Valley
A valley section too flat to drain, where water collects and sits.
Designer (Premium) Shingles
Thick, luxury-profile shingles that mimic slate or wood shake.
Dormer
A structure projecting from a sloped roof with its own window and roof.
Drip Edge
Angled metal flashing along roof edges that directs water into the gutters instead of behind them.
Eave
The lower edge of the roof that overhangs the exterior wall.
EPDM Roofing
A black synthetic-rubber membrane for flat and low-slope roofs.
Exhaust Ventilation
The vents — ridge, box, turbine — that let hot, moist air escape the attic.
Fascia
The vertical boards behind your gutters that cap the ends of the rafters.
Felt Underlayment
Asphalt-saturated paper — the traditional underlayment used under shingles for decades.
Fishmouthing
Shingle tabs lifting at the center to form a gaping, mouth-like opening.
Flashing
Metal strips that waterproof the joints, valleys, and penetrations in your roof.
Gable
The triangular wall section between the edges of a sloped roof.
Gable Vent
Louvered vents set into the gable-end walls near the peak.
Granule Loss
The wearing away of the ceramic-coated mineral granules that protect shingles.
Gutter Apron
An L-shaped flashing that extends from under the shingles into the gutter.
Hail Bruise
A soft, fractured spot on a shingle where hail impact broke the mat beneath.
High Nailing
Driving shingle nails above the manufacturer's nailing zone — a serious defect.
Hip
The external angled ridge where two roof slopes meet at an outside corner.
Ice and Water Shield
A self-adhering waterproof membrane that seals around nail penetrations.
Ice Dam
A ridge of ice at the roof's edge that traps meltwater behind it.
Impact Rating (Class 4 Shingles)
The hail-resistance classification for shingles; Class 4 is the highest.
Insulation Baffle
A chute that holds insulation back so soffit vents stay open to airflow.
Intake Ventilation
The vents — usually at the soffits — that bring fresh air into the attic.
Kickout Flashing
A small angled flashing that kicks roof runoff into the gutter at wall junctions.
Lichen on Roofs
Crusty, circular organisms that anchor into shingle granules.
Modified Bitumen
Polymer-reinforced asphalt rolls for flat and low-slope roofs.
Moss on Roofs
Green, spongy plant growth that holds moisture against the roof surface.
Nailing Zone
The reinforced strip on a shingle where nails must be placed.
Net Free Area (NFA)
The actual open airflow area of a vent, after subtracting louvers and screens.
Off-Ridge Vent
An exhaust vent installed on the slope below the ridge, used where ridge vents cannot go.
Open Valley
A valley style with metal flashing left visible as an open water channel.
Overdriven Nails
Nails driven too deep, breaking through the shingle's reinforcing mat.
Parapet Wall
A low wall extending above the edge of a flat roof.
Pipe Boot (Vent Flashing)
The flashing collar — usually rubber over metal — sealing a vent pipe through the roof.
Ponding Water
Standing water that remains on a roof 48 hours or more after rain.
Powered Attic Ventilator
An electric fan that actively exhausts hot air from the attic.
Rafter
The sloped structural beams that support the roof deck.
Rake
The sloped edge of a gable roof, running from eave to ridge.
Re-Roof
Replacing the roofing system — typically a full tear-off and new installation.
Ridge
The horizontal peak where two roof slopes meet.
Ridge Board
The horizontal board at the peak that pairs of rafters nail into.
Ridge Cap Shingles
Pre-bent shingles that straddle the roof's peak and shed water to both sides.
Ridge Vent
A continuous vent along the roof's peak that exhausts hot attic air.
Roll Roofing
Asphalt roofing sold in rolls for low-slope utility structures.
Roof Cricket (Saddle)
A small peaked structure that diverts water around a chimney or roof penetration.
Roof Decking (Sheathing)
The wood layer — plywood or OSB — that shingles and underlayment nail into.
Roof Fire Rating (Class A/B/C)
The classification of a roof's resistance to external fire; Class A is highest.
Roof Overlay
Installing new shingles directly over the existing shingle layer.
Roof Pitch
The steepness of a roof, expressed as inches of rise per 12 inches of run.
Roof Truss
A prefabricated triangular frame that supports the roof structure.
Roof Underlayment
The water-resistant layer installed between the roof deck and the shingles.
Roofing Square
The industry unit of roof area: 100 square feet.
Scupper
An opening through a parapet wall that drains water off a flat roof.
Shingle Blistering
Raised bubbles in shingles caused by trapped moisture expanding in heat.
Shingle Clawing
The center of a shingle lifting while the edges stay nailed down.
Shingle Cupping
Shingle edges turning upward while the center stays down, like a cup.
Shingle Curling
Shingle edges lifting and turning upward — a classic sign of an aging roof.
Shingle Delamination
Separation of the laminated layers within a shingle.
Skylight
A window installed in the roof plane to bring in daylight.
Slate Roofing
Natural stone roofing with a service life measured in generations.
Soffit
The finished underside of your roof's overhang — and the entry point for attic intake ventilation.
Soffit Vent
Vents in the soffit that supply fresh intake air to the attic.
Solar Attic Fan
A small solar-powered fan that exhausts hot attic air.
Standing Seam Metal Roofing
Metal roofing with raised, interlocking seams and concealed fasteners.
Starter Strip
The first course of shingles at eaves and rakes, with adhesive that seals the edge.
Step Flashing
L-shaped metal pieces woven into the shingles where a roof meets a vertical wall.
Synthetic (Composite) Shingles
Engineered polymer shingles that mimic slate or wood shake.
Synthetic Underlayment
Lightweight, tear-resistant polymer underlayment — the modern alternative to felt.
Tear-Off
Stripping all old roofing layers down to the bare wood deck.
Thermal Shock
Damage from rapid temperature swings stressing roofing materials.
Thermal Splitting
Cracks in shingles caused by repeated thermal expansion and contraction.
TPO Roofing
A white, heat-welded single-ply membrane for flat and low-slope roofs.
Turbine Vent (Whirlybird)
A wind-spun metal vent that pulls air from the attic as it rotates.
UL 2218
The standard laboratory test for roofing impact (hail) resistance.
Valley
The V-shaped channel where two roof slopes meet and water converges.
Valley Flashing
The metal or membrane lining installed beneath shingles in a roof valley.
Ventilation Ratio (1/150 Rule)
The code rule requiring 1 sq ft of vent area per 150 sq ft of attic floor.
Wind Rating
The certified wind speed a roofing system is tested to resist.
Wind Uplift
The aerodynamic suction force that lifts roofing materials off the deck.
Woven Valley
A valley with shingles from both slopes interlaced across the channel.
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