Comprehensive Roofing Glossary
A-Z guide to roofing terminology, definitions, and industry terms
Understanding roofing terminology is essential for homeowners, contractors, and anyone involved in roofing projects. This comprehensive glossary defines common and technical terms used in the roofing industry.
A
Aggregate
Crushed stone, rock, or gravel used as a protective layer on built-up roofs.
Algae Discoloration
Dark streaks or stains on roofs caused by algae growth, common in humid climates.
Architectural Shingles
Also called dimensional or laminated shingles, these are thicker than standard 3-tab shingles with a textured appearance.
Asphalt
A bituminous waterproofing material used in roofing products like shingles, roll roofing, and built-up roofing.
ASTM
American Society for Testing and Materials - organization that sets standards for roofing materials.
B
Base Flashing
The portion of flashing attached to or resting on the deck to direct water flow.
Batten
Horizontal or vertical wood strips used to secure roofing materials, especially tiles.
Bird Stop
A barrier installed at the eave to prevent birds from nesting under tile roofs.
Blistering
Bubbles or raised areas in roofing materials caused by trapped moisture or air.
Built-Up Roof (BUR)
A flat or low-slope roof consisting of multiple layers of bitumen and reinforcing fabrics.
Bundle
A package of shingles. Typically, 3 bundles cover one square (100 square feet).
C
Cap Sheet
The top layer of a built-up roof, usually granule-surfaced for UV protection.
Caulk
Sealant used to fill gaps and prevent water infiltration.
Class A, B, C Fire Rating
Fire resistance ratings for roofing materials, with Class A being the most fire-resistant.
Closed Valley
A valley where shingles from both sides meet in the middle without exposed flashing.
Collar Beam
Horizontal framing member that connects opposing rafters.
Condensation
Water vapor that turns to liquid when warm air meets a cold surface.
Cricket
A peaked structure installed behind chimneys or other projections to divert water.
Curb
A raised frame used to mount skylights or equipment on a roof.
D
Dead Load
The constant weight of the roof structure itself.
Deck
The structural surface to which roofing materials are applied, typically plywood or OSB.
Dormer
A structure projecting from a sloped roof, usually containing a window.
Downspout
Pipe that carries water from gutters to the ground or drainage system.
Drip Edge
Metal flashing installed at roof edges to direct water into gutters.
E
Eave
The horizontal, lower edge of a sloped roof that extends beyond the wall.
EPDM
Ethylene Propylene Diene Monomer - a synthetic rubber roofing membrane.
Exposure
The portion of roofing material exposed to weather after installation.
F
Fascia
Vertical board that caps the end of rafters at the eave.
Felt
Fibrous material saturated with asphalt, used as underlayment.
Flashing
Metal or other material used to prevent water infiltration at roof intersections and projections.
Flashing Cement
Sealant used to bond roofing materials and flashing.
G
Gable
The triangular portion of a wall between the edges of a sloping roof.
Gable Roof
A roof with two sloping sides that meet at a ridge.
Galvanized Steel
Steel coated with zinc to prevent corrosion.
Granules
Crushed rock coated with ceramic coating, applied to shingles for UV protection.
Gutter
Channel that collects and diverts water from the roof edge.
H
Hip
The inclined external angle formed by two sloping roof planes.
Hip Roof
A roof with four sloping sides.
HVAC
Heating, Ventilation, and Air Conditioning equipment often mounted on roofs.
I
Ice Dam
Ice formation at the eave that can cause water backup under shingles.
Ice and Water Shield
Self-adhering membrane installed at eaves and valleys for ice dam protection.
Impact Resistance
A material's ability to withstand hail damage, rated Class 1-4.
Insulation
Material used to reduce heat transfer, measured in R-value.
J
Joist
Horizontal structural member supporting a ceiling or floor.
L
Laminated Shingles
See Architectural Shingles.
Lap
The overlap of one roofing material over another.
Live Load
Temporary loads on a roof such as people, equipment, or snow.
Low Slope
A roof with a pitch between 2:12 and 4:12.
M
Mansard Roof
A roof with two slopes on all four sides, the lower slope being steeper.
Membrane
A flexible or semi-flexible roof covering, especially for flat roofs.
Metal Roofing
Roofing made from metal pieces or tiles, including steel, aluminum, copper, and zinc.
Modified Bitumen
Rolled roofing membrane with polymer-modified asphalt.
N
Nail Pop
When a nail works its way up through roofing material.
Nesting
Installing new shingles over old ones without removing the existing layer.
Net Free Area (NFA)
The unobstructed area through which air can pass in a vent.
O
Open Valley
A valley with exposed metal flashing where shingles don't meet.
OSB
Oriented Strand Board - engineered wood used for roof decking.
Overhang
The extension of the roof beyond the exterior wall.
P
Parapet
A low wall that extends above the roofline.
Penetration
Any object passing through the roof plane.
Plywood
Wood panels made from thin sheets glued together, used for decking.
Ponding
Standing water on a flat roof for more than 48 hours.
PVC
Polyvinyl Chloride - a single-ply roofing membrane.
R
Rafter
Structural member supporting the roof deck and loads.
Rake
The inclined edge of a sloped roof over a wall.
Re-roofing
Installing new roofing over existing roofing.
Ridge
The horizontal line at the top where two roof planes meet.
Ridge Vent
Ventilation installed along the ridge for attic air exhaust.
Rise
The vertical distance from eave to ridge.
Roll Roofing
Asphalt roofing products in roll form.
Run
The horizontal distance from eave to ridge.
S
Saturant
Asphalt used to impregnate felt for waterproofing.
Scupper
Drainage opening in a parapet wall.
Sheathing
See Deck.
Shed Roof
A roof with only one sloping plane.
Shingle
Small unit of roofing material designed to be installed in overlapping rows.
Slope
The incline of a roof expressed as a percentage or degrees.
Snow Guard
Device to prevent snow from sliding off a roof.
Soffit
The underside of the roof overhang.
Square
A unit of roof measurement equal to 100 square feet.
Standing Seam
Metal roofing system with raised seams joining panels.
Starter Strip
The first course of shingles installed at the eave.
Step Flashing
Flashing installed where a roof meets a wall, overlapped like steps.
T
Tab
The exposed portion of a shingle with cutouts.
Tear-off
Complete removal of existing roofing materials.
Three-tab Shingle
Asphalt shingle with three tabs of equal size.
TPO
Thermoplastic Polyolefin - a single-ply roofing membrane.
Truss
Engineered structural component supporting the roof.
U
Underlayment
Material installed on the roof deck before the primary roofing material.
UL
Underwriters Laboratories - organization that tests and rates roofing materials.
V
Valley
The internal angle formed where two sloping roof planes meet.
Vapor Barrier
Material used to prevent moisture passage into the roofing system.
Vent
Opening designed to allow air flow for moisture control.
W
Warranty
Written promise regarding product performance and coverage period.
Waterproofing
Treatment to prevent water passage.
Weep Holes
Small openings allowing water drainage.
Wind Uplift
Force caused by wind pressure that can lift roofing materials.
Woven Valley
Valley construction where shingles from both sides are woven together.
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