Glossary of Roofing Terminology
A
Accelerated Weathering – Laboratory testing that simulates years of weather exposure in a compressed timeframe to evaluate roofing material durability.
Acrylic Coating – A water-based reflective roof coating used primarily on flat or low-slope roofs to extend roof life and improve energy efficiency.
Adhesion – The bond strength between roofing materials, such as shingles to underlayment or coating to substrate.
Aggregate – Gravel, crushed stone, or slag used as a surfacing material on built-up roofs and modified bitumen systems.
Air Infiltration – Uncontrolled air leakage through the building envelope, often around roof penetrations and edges.
Algae Discoloration – Black or dark staining on asphalt shingles caused by airborne algae (Gloeocapsa magma), common in humid climates.
Algae-Resistant Shingles – Asphalt shingles containing copper granules that inhibit algae growth and prevent black streaking.
Alligatoring – Surface cracking pattern on built-up roofs resembling alligator skin, caused by loss of volatiles and weathering.
Aluminum Roofing – Metal roofing panels or shingles made from aluminum, offering lightweight, corrosion-resistant coverage.
Ambient Temperature – The surrounding air temperature, critical for proper installation of roofing materials.
Anchor – Fastener designed to secure roofing membranes to the deck or substrate.
ANSI – American National Standards Institute, which develops standards for roofing materials and installation.
Anti-Siphon Valve – Plumbing device that prevents backflow, commonly found in roof drain systems.
Apron Flashing – Metal flashing piece installed at the junction of a roof and vertical wall, chimney base, or other protrusion.
Architectural Shingles – Premium laminated asphalt shingles with dimensional appearance, also called dimensional or laminated shingles.
Area Divider – Raised metal flashing used to separate different sections of a roof system.
Asbestos – Hazardous fibrous mineral once used in roofing materials, now banned but present in older roofs requiring special abatement.
Asphalt – Bituminous waterproofing agent used in various roofing materials including shingles, underlayment, and built-up roofing.
Asphalt Cement – Asphalt-based adhesive used to bond roofing materials.
Asphalt Felt – Organic or fiberglass felt saturated with asphalt, used as underlayment.
Asphalt Plastic Cement – Trowel-grade adhesive used for flashing and patching.
Asphalt Primer – Thin liquid asphalt applied to prepare surfaces for waterproofing membranes.
Asphalt Roof Cement – Thick adhesive compound used for general roofing repairs and flashing installation.
ASTM – American Society for Testing and Materials, which establishes standards for roofing materials and testing methods.
Attic – Space between the roof deck and ceiling of the top floor.
Attic Ventilation – System of intake and exhaust vents that provide airflow through attic spaces.
B
Back Surfacing – Fine mineral matter applied to the back side of shingles to prevent sticking in bundles.
Baffle – Device installed in attic spaces to maintain proper airflow from soffit vents to ridge vents.
Ballast – Heavy material (gravel, pavers, concrete blocks) placed on membrane roofs to hold the system in place.
Barge Board – Decorative trim board attached to the gable end of a roof, also called verge board.
Base Flashing – Portion of flashing attached to the vertical surface to direct water onto the roof covering.
Base Ply – The bottom layer in a multi-ply built-up or modified bitumen roof system.
Base Sheet – The first ply of roofing material in some low-slope roof systems.
Batt Insulation – Blanket-type insulation used between framing members in attics and cathedral ceilings.
Batten – Narrow strip of wood or metal used to secure or space roofing materials, common in metal and tile roofing.
Batten Seam – Metal roofing seam formed over a vertical wood or metal batten.
Bird Stop – Device installed at the eaves to prevent birds from nesting under tile roofs.
Bitumen – Generic term for various mixtures of hydrocarbons, including asphalt and coal tar.
Blind Nailing – Nailing pattern where fasteners are covered by subsequent roofing materials.
Blister – Bubble or raised area in roofing membranes caused by trapped moisture or air.
Blow-Off – Wind damage where roofing materials are lifted or removed from the deck.
Bond – Adhesive connection between roofing materials or the warranty provided by manufacturers.
Bond Breaker – Material used to prevent adhesion between two surfaces where independent movement is needed.
Box Vent – Static exhaust vent installed on the roof deck, providing attic ventilation.
Broom Finish – Texture created on concrete by pulling a broom across the surface before it sets.
Buckling – Wrinkling or rippling of roofing materials caused by improper installation or substrate movement.
Building Code – Municipal regulations governing construction standards, including roofing requirements.
Building Envelope – Physical separator between the conditioned interior and unconditioned exterior of a building.
Built-Up Roofing (BUR) – Low-slope roofing system consisting of multiple layers of bitumen and reinforcing fabrics.
Bundle – Package of roofing shingles, typically containing enough material to cover 33.3 square feet.
Butt Edge – Lower exposed edge of a shingle.
Butyl – Rubber-like material used in sealants and flashings, known for excellent waterproofing properties.
Butyl Tape – Adhesive sealing tape used for flashing and sealing joints.
C
Cant Strip – Beveled wood or rigid insulation strip placed at the junction of roof deck and vertical surface to relieve stress.
Cap Flashing – Flashing piece that covers or shields the top edge of base flashing, wall flashing, or other components.
Cap Sheet – Granule-surfaced top sheet of a built-up or modified bitumen roofing system.
Capillary Action – Movement of water through small openings or between surfaces due to surface tension.
Caulk – Flexible sealant used to fill gaps and joints, preventing water infiltration.
Cathedral Ceiling – Vaulted ceiling that follows the roofline, requiring special insulation and ventilation.
Cavity Wall – Wall constructed with airspace between inner and outer layers.
Cement Tile – Heavy concrete roofing tiles shaped to resemble clay or slate.
Ceramic Granules – Colored mineral particles embedded in asphalt shingle surfaces.
Chalk Line – String coated with chalk dust used to mark straight lines for installation alignment.
Chimney – Vertical structure extending through the roof for venting combustion gases.
Chimney Cricket – Small peaked saddle installed behind chimneys to divert water and debris.
Clad – Metal covering applied to enhance durability and appearance of roofing components.
Cladding – Exterior covering of a building.
Clamp Ring – Metal ring used to secure membrane roofing around pipe penetrations.
Class A, B, C Fire Rating – Fire resistance classifications with Class A being most fire-resistant.
Clay Tile – Traditional roofing tile made from fired clay, available in various profiles and colors.
Cleat – Metal piece used to secure metal roofing panels or flashings.
Cleavage – Tendency of materials to separate along defined planes.
Clerestory – Vertical window section rising above adjacent rooflines.
Clip – Fastening device used to attach metal roofing panels while allowing thermal movement.
Closed-Cut Valley – Valley installation where one roof plane’s shingles extend across the valley.
Coal Tar – Bituminous material once widely used in built-up roofing, now less common.
Coal Tar Pitch – Dark brown to black cementitious material used in waterproofing.
Coating – Liquid-applied material that cures to form a protective membrane on roof surfaces.
Cold Applied Adhesive – Adhesive that doesn’t require heating before application.
Cold Process Roofing – Built-up roof using cold-applied adhesives rather than hot asphalt.
Collar Beam – Horizontal framing member connecting opposite rafters above the wall plate.
Combustible – Materials capable of igniting and burning.
Condensation – Water vapor that converts to liquid when contacting cold surfaces.
Conductor Head – Decorative box at the top of a downspout that receives water from gutters.
Continuous Ridge Vent – Ventilation system running the entire length of the roof ridge.
Coping – Covering or cap on top of a wall exposed to weather.
Copper – Durable metal used for roofing, flashing, and gutters, develops natural green patina over time.
Cornice – Decorative horizontal molding at the junction of wall and roof overhang.
Corrosion – Deterioration of metal through chemical or electrochemical reaction with environment.
Counter Flashing – Flashing installed opposite or above base flashing to shed water.
Course – Horizontal row of shingles or other roofing materials.
Coverage – Surface area covered by a given amount of roofing material.
Cricket – Peaked saddle structure designed to divert water around projections through the roof.
Crickets – Plural of cricket; multiple diversion structures.
Crosslap – Lapped joint between rolls of roofing membrane running perpendicular to each other.
Crown – Highest point of a roof or arch.
Cupola – Small dome-like structure on a roof, often with ventilation louvers.
Curb – Raised frame around roof openings for mechanical equipment or skylights.
Cure – Chemical process where roofing materials reach full strength and adhesion.
Cutback – Solvent-thinned bitumen used for priming and cementing.
Cutoff – Detail designed to seal and prevent lateral water movement in an insulation system.
Cutout – Open space between tabs on a shingle.
D
Damper – Device controlling airflow in HVAC systems or chimneys.
Datum Point – Reference point from which roof elevations are measured.
Dead Level – Absolutely flat, or zero slope.
Dead Load – Permanent structural weight of the roof assembly.
Deck – Structural surface to which roofing materials are applied.
Deck Fasteners – Nails or screws securing decking to structural supports.
Deck Seam – Joint between adjacent roof deck panels.
Deflection – Displacement of structural members under load.
Delamination – Separation of laminated roofing materials.
Delta T – Temperature difference across an assembly, important for thermal performance.
Detailing – Specific construction methods for transitions, terminations, and penetrations.
Dew Point – Temperature at which water vapor condenses into liquid.
Dimensional Shingles – See Architectural Shingles.
Dormer – Framed window projection through a sloping roof.
Double Coverage – Application where underlayment or shingles overlap to provide two layers.
Downspout – Vertical pipe carrying water from gutters to ground or drainage system.
Drain – Device allowing water to flow from the roof surface.
Drainage Mat – Three-dimensional material providing drainage space in wall or roof assemblies.
Drip Edge – Metal flashing installed at roof edges to direct water away from fascia.
Drip Line – Point where water drips from an eave or overhang.
Dry-In – Process of making a roof weathertight.
Dutch Hip – Roof style combining gable and hip features.
Dutch Lap – Siding pattern sometimes confused with roofing patterns.
E
Eave – Lower edge of a roof projecting beyond the exterior wall.
Eave Flashing – Additional waterproofing membrane installed at eaves to prevent ice dam damage.
Eave Vent – Intake ventilation installed at the eaves or soffits.
Edge Metal – Metal flashing at roof perimeters.
Edge Stripping – Application of feltstrips cut to narrower widths than the standard roll width.
Edge Venting – Ventilation system installed at roof perimeters.
Elastomer – Rubber-like material that returns to original shape after stretching.
Elastomeric – Having elastic properties.
Elastomeric Coating – Flexible coating that can expand and contract with temperature changes.
Elongation – Measure of a material’s ability to stretch before breaking.
Embossed – Surface texture created by pressing patterns into materials.
Embedment – Pressing roofing materials into adhesive or coating.
End Dam – Closure at the end of a valley or eave to prevent water migration.
End Lap – Length of overlap where one ply extends over another.
End Wall – Wall at the gable end of a building.
EPDM – Ethylene Propylene Diene Monomer, a synthetic rubber membrane roofing material.
Equalization – Process of equalizing air pressure in insulation and membrane systems.
Equilibrium Moisture Content – Moisture content at which material neither gains nor loses moisture.
Erosion – Wearing away of surface material through weather exposure.
Exhaust Vent – Ventilation component allowing air to escape from attic or roof cavity.
Expansion Joint – Assembly designed to accommodate thermal movement of building components.
Exposure – Portion of roofing material exposed to weather.
Exposed Nail Method – Fastening where nail heads remain visible.
Extender – Material added to coatings to increase volume or modify properties.
F
Fabric – Woven or non-woven reinforcing material in roofing membranes.
Face Fastening – Exposed fastening through the face of metal panels.
Factory Mutual (FM) – Testing organization providing ratings for roof assemblies, particularly for wind and fire resistance.
Factory Seam – Seam created during membrane manufacturing, generally stronger than field seams.
Fascia – Vertical board installed at roof edge, often supporting gutters.
Fastener – Generic term for nails, screws, or other attachment devices.
Felt – Generic term for sheet materials used as underlayment, historically organic felt, now often synthetic.
Ferrule – Metal sleeve or ring used to strengthen or protect an opening.
Fiberglass – Material made from fine glass fibers, used in shingles and insulation.
Fiberglass Mat – Non-woven glass fiber reinforcement used in shingle manufacturing.
Field – Central area of a roof, away from perimeter and penetrations.
Field Applied – Materials or methods applied at the job site rather than in a factory.
Field Seam – Seam created on-site during installation.
Filler – Material added to compounds to modify properties or reduce cost.
Fillet – Triangular-shaped sealant or cement at the junction of surfaces.
Film – Thin continuous sheet of material.
Fire Rating – Classification indicating fire resistance performance.
Fire-Resistance – Property of materials that resist combustion and spread of flames.
Fishmouth – Edge wrinkle or opening in roofing membrane laps.
Flame Spread – Rate at which flame travels across a material surface.
Flange – Projecting edge or rim used for attachment.
Flashing – Materials used to weatherproof or seal roof system edges, penetrations, walls, valleys, and other interruptions.
Flashing Cement – Trowel-grade sealant used to seal and adhere flashings.
Flat Roof – Roof with minimal slope, typically less than 2:12, though technically level roofs are rare.
Fleece-Backed Membrane – Single-ply membrane with an attached fleece layer to absorb adhesive.
Flood Coat – Top layer of bitumen into which aggregate is embedded on built-up roofs.
Fluid-Applied Membrane – Liquid coating that cures to form seamless waterproofing.
Flute – Corrugation in metal panels.
Freeze-Thaw Cycling – Repeated freezing and thawing that damages roofing materials.
Friable – Materials that crumble easily, particularly concerning with asbestos.
Fully Adhered – Membrane attached to substrate across entire surface.
Furring – Strips of wood or metal used to create space or level a surface.
G
Gable – Triangular wall section at the end of a ridged roof.
Gable Roof – Roof style with two sloping planes meeting at a ridge, creating gable ends.
Gable Vent – Ventilation opening in a gable wall.
Galvanic Action – Electrochemical reaction between dissimilar metals in presence of electrolyte.
Galvanized Steel – Steel coated with zinc for corrosion protection.
Gambrel Roof – Roof with two slopes on each side, the lower slope steeper than the upper.
Gauge – Thickness measurement for metal, with higher numbers indicating thinner material.
Glaze Coat – Thin protective coating applied to built-up roofs.
Gloss – Measure of light reflection from a surface.
Gooseneck – Curved section of downspout that extends outward from wall.
Gradation – Particle size distribution in aggregate or coating materials.
Grain – Natural fiber direction in wood decking.
Granule – Ceramic-coated mineral particles that protect and color asphalt shingles.
Gravel – Coarse aggregate used to surface and ballast built-up roofs.
Gravel Stop – Raised metal flashing at roof perimeter that prevents gravel migration.
Green Roof – Roof system incorporating vegetation and growing medium over waterproofing.
Gutter – Channel at roof edge collecting and conveying water to downspouts.
Gutter Apron – Metal flashing extending under shingles and over gutter edge.
Gutter Guard – Protective device preventing debris from entering gutters.
H
Hail Resistance – Ability to withstand impact from hailstones, rated Class 1-4 (UL 2218).
Hand Sealing – Manual application of sealant to shingle tabs.
Hand-Mop – Application method using mop to spread hot asphalt.
Head Flashing – Flashing installed at the top of a wall or window opening.
Head Lap – Shortest distance from butt edge of overlying shingle to top of underlying shingle.
Header – Structural beam supporting roof framing at openings.
Heat Welding – Joining method using heat to fuse thermoplastic roofing membranes.
Heated-Air Welding – Hot air used to soften and fuse membrane seams.
Heating Cable – Electric cable installed in valleys and eaves to prevent ice dams.
Heavy Mineral-Surfaced Roofing – Rolled roofing with granule coating on exposed surface.
Hem – Folded edge on metal flashing for safety and rigidity.
Hidden Fastener – Concealed attachment system for metal roofing panels.
High-Nailing – Improper nailing above the self-seal strip on shingles.
Hip – Inclined external angle formed by intersection of two sloping roof planes.
Hip and Ridge Shingles – Preformed shingles designed for hip and ridge applications.
Hip Leg – One of two slopes forming a hip.
Hip Roof – Roof with sloping planes on all sides.
Holiday – Void or gap in applied coating or membrane.
Hook Blade – Roofing knife blade with hooked tip for cutting shingles.
Hot Asphalt – Asphalt heated to liquid state for application in built-up roofing.
Hot Mop – Application of hot asphalt using a mop.
Hot Stuff – Slang term for hot asphalt.
Hurricane Clip – Metal connector securing rafters to wall plates in high-wind zones.
Hurricane Strap – Metal strap reinforcing roof-to-wall connections.
HVAC – Heating, Ventilation, and Air Conditioning systems that penetrate roofs.
Hydrostatic Pressure – Pressure exerted by standing water.
I
Ice and Water Shield – Self-adhering waterproofing membrane for vulnerable roof areas.
Ice Dam – Ice buildup at eaves preventing proper drainage, causing leaks.
Ice Guard – See Ice and Water Shield.
Impact Resistance – Ability to withstand strikes without damage, tested per UL 2218 or FM 4473.
Infrared Thermography – Diagnostic technique using thermal imaging to detect moisture or insulation deficiencies.
Insulation – Material reducing heat transfer through roof assemblies.
Intake Ventilation – Vents allowing outside air into attic spaces, typically at soffits.
Interlayment – Material placed between roof system components.
Interply – Between layers of roofing membrane.
Inverted Roof Membrane Assembly (IRMA) – System with insulation above waterproofing membrane.
J
J-Channel – Metal trim with J-shaped profile used at siding and flashing transitions.
Jack Rafter – Rafter shorter than full span, running from ridge to valley or ridge to hip.
Joist – Horizontal structural member supporting floor or ceiling loads.
K
Kantmiss – Slang for cant strip.
Kerf – Saw cut or groove in material.
Kettle – Equipment for heating asphalt to application temperature.
Knee Wall – Short vertical wall often found in attic spaces.
L
Ladder – Stepwise pattern of installing asphalt shingles up roof slope.
Laminated Shingles – See Architectural Shingles.
Lap – Area where one piece of roofing overlays another.
Lap Cement – Adhesive specifically formulated for bonding membrane laps.
Lap Seam – Joint created by overlapping materials.
Lead – Heavy metal used for roof flashings, particularly around chimneys and vents.
Lead Pipe Boot – Flashing for plumbing vent pipes made from lead.
Lean-to – Single-slope roof attached to a higher wall.
Lift – Stack height of roofing materials being applied.
Live Load – Temporary loads from snow, wind, people, or equipment.
Lookout – Horizontal framing member extending from wall to support rake overhang.
Loose-Laid – Roofing membrane not attached to substrate except at perimeter and penetrations.
Louver – Slatted vent allowing air passage while blocking rain.
Low-Slope Roof – Roof with slope less than 3:12.
M
Mansard Roof – Roof with two slopes on all four sides, lower slope nearly vertical.
Manufacturer’s Warranty – Guarantee provided by product manufacturer for specific period.
Mastic – General term for thick adhesive or coating compounds.
Mat – Reinforcing fiber sheet used in shingle manufacturing.
Mechanically Attached – System fastened with screws, nails, or plates rather than adhesive.
Membrane – Flexible sheet material forming waterproof barrier.
Metal Flashing – Formed metal pieces used for waterproofing transitions and penetrations.
Metal Panel – Interlocking metal roofing or wall covering.
Metal Roof – Roofing system using metal panels or shingles as primary covering.
Mil – Unit of thickness equal to 0.001 inch.
Mildew – Fungal growth on surfaces in damp conditions.
Mineral Granules – Ceramic-coated particles surfacing asphalt shingles.
Mineral-Surfaced Roofing – Built-up or roll roofing with granulated top surface.
Mineral Spirits – Petroleum-based solvent.
Mitered – Angled cut allowing two pieces to join at corner.
Modified Bitumen – Asphalt modified with polymers for enhanced performance, used in roll roofing membranes.
Moisture Scan – Electronic or infrared survey to locate wet insulation or deck.
Mopping – Application of hot asphalt with mop.
Mopping Asphalt – Hot asphalt used to adhere roofing plies.
Mortar – Cement-based mixture bonding masonry units.
Mud – Slang for roofing cement or mastic.
N
Nail-Base – Substrate suitable for fastener attachment, typically wood or approved structural panel.
Nailing Pattern – Specified locations and spacing for fasteners.
Neoprene – Synthetic rubber used in flashings and sealants.
Net Free Ventilation Area (NFVA) – Actual unobstructed area through which air can flow.
Night Seal – Temporary seal allowing work to resume next day.
Nineteen-Inch Selvage – Rolled roofing with 17-inch granule coverage and 19-inch smooth edge.
Non-Woven – Fabric construction using random fiber orientation.
Nosing – Drip edge of a roof.
O
Off-Ridge Vent – Static vent installed near but not at ridge line.
Offset – Horizontal measurement from structure to valley or other feature.
Open Valley – Valley where metal flashing remains exposed between roof planes.
Organic Felt – Underlayment made from cellulose fibers saturated with asphalt.
Organic Shingle – Asphalt shingle reinforced with organic felt (cellulose), mostly discontinued.
Orientation – Directional placement of roofing materials.
OSB (Oriented Strand Board) – Engineered wood panel used for roof decking.
Outrigger – Extension of rafter beyond wall to support overhang.
Overhang – Portion of roof extending beyond exterior wall.
Overlap – Area where adjacent materials cover each other.
Over-Nailing – Excessive fastener penetration damaging roofing materials.
Over-Roofing – Installing new roofing over existing materials.
P
Pallet – Wooden platform for shipping and storing bundled roofing materials.
Pan – Flat area of metal roofing panel between ribs.
Parapet – Vertical wall extension above roof line.
Parapet Wall – Low protective wall along roof edge.
Parge Coat – Thin mortar coating over masonry.
Particle Board – Engineered wood product, generally not suitable for roof decking.
Paver – Concrete or stone units used on ballasted roof systems.
Peak – Highest point of a roof, generally the ridge.
Peel Strength – Force required to separate adhered materials.
Penetration – Any object passing through the roof membrane (pipes, vents, equipment supports).
Performance Specification – Specification defining required results rather than specific materials or methods.
Perm (Permeance) – Measure of water vapor transmission through materials.
Petrochemical – Chemical derived from petroleum or natural gas.
Picture Framing – Fastening pattern around perimeter of roofing sections.
Pipe Boot – Prefabricated flashing fitting around pipe penetrations.
Pipe Flashing – See Pipe Boot.
Pitch – Roof slope expressed as ratio of rise to run, or degree of angle.
Pitch Pan – Obsolete flashing method using metal pan filled with sealant around penetrations.
Pitch Pocket – See Pitch Pan.
Plastic Cement – Trowel-grade asphalt-based adhesive.
Plate – Horizontal framing member at top of wall supporting roof structure.
Ply – Single layer of roofing material in a multi-layer system.
Ply Sheet – Reinforcing fabric in built-up roofing.
Plywood – Engineered wood panel made of thin wood veneers, commonly used for roof decking.
Ponding – Water standing on roof more than 48 hours after rain.
Positive Drainage – Roof design ensuring water flows to drains without ponding.
Pot Life – Time window after mixing during which material remains workable.
Power Vent – Electrically powered exhaust fan for attic ventilation.
Pre-Formed Flashing – Factory-fabricated flashing pieces.
Pressure Relief Valve – Device preventing pressure buildup in roofing systems.
Prevailing Wind – Predominant wind direction in a geographic area.
Primary Roof – Main weatherproofing layer of roof assembly.
Prime Coat – Initial coating preparing surface for subsequent materials.
Protected Membrane Roof – System with insulation above waterproofing membrane.
PSF (Pounds Per Square Foot) – Unit of load or weight measurement.
PSI (Pounds Per Square Inch) – Pressure measurement unit.
Pull Test – Destructive test measuring fastener withdrawal resistance.
Purlin – Horizontal structural member supporting roof deck or rafters.
PVC (Polyvinyl Chloride) – Thermoplastic material used in single-ply roofing membranes.
Q
Quarry Tile – Unglazed clay tile sometimes used as ballast.
Quarter Cut – Lumber sawn perpendicular to growth rings.
R
R-Value – Measure of thermal resistance; higher values indicate better insulation.
Racking – Method of shingle installation proceeding diagonally up roof.
Radiant Barrier – Reflective material reducing radiant heat transfer.
Rafter – Inclined structural member supporting roof deck.
Rafter Square – Triangular measuring tool used for laying out rafters.
Rafter Tail – Portion of rafter extending beyond exterior wall.
Rain Cap – Cover on vent pipe preventing water entry.
Rainscreen – Drainage cavity behind wall cladding.
Rake – Inclined edge of roof at gable end.
Rake Board – Trim board along gable edge.
Rake Starter – Special shingles beginning rake edge coverage.
Rated-Sheathing – Plywood or OSB panels meeting specific structural ratings for roof decking.
Re-Cover – Installing new roofing over existing materials.
Re-Roof – Removing existing roofing and installing new system.
Recovery – Ability of roofing membrane to return to original shape after stress.
Reflectance – Percentage of light reflected by a surface.
Reflective Roof Coating – Light-colored coating reducing solar heat gain.
Reglet – Groove cut or formed in masonry for flashing insertion.
Reinforcement – Material (fabric, mat, or mesh) strengthening roofing membranes.
Release Film – Protective film removed before membrane installation.
Release Paper – Removable paper protecting adhesive until use.
Replacement Shingle – Shingle designed to match existing roof during repairs.
Resilience – Ability to recover from deformation.
Resins – Compounds providing flexibility and adhesion in roofing materials.
Resistance to Wear – Durability against abrasion and traffic.
Retrofit – Modification of existing roof system.
Reveal – Exposed portion of roofing material.
Rib – Raised profile on metal roofing panels.
Ridge – Horizontal line at top of roof where two slopes meet.
Ridge Board – Horizontal board at ridge against which rafters bear.
Ridge Cap – Covering material protecting ridge.
Ridge Course – Final course of shingles at ridge.
Ridge Shingles – Preformed shingles for ridge and hip coverage.
Ridge Vent – Continuous ventilation along entire ridge length.
Rise – Vertical distance from wall plate to ridge.
Rivet – Metal fastener used in metal roofing and flashing.
Roll Roofing – Asphalt roofing material in rolls, used on low-slope roofs.
Roof Assembly – Complete system of all roofing components.
Roof Cement – General term for asphalt-based adhesives and sealants.
Roof Curb – Raised frame around roof openings.
Roof Deck – Structural surface supporting roofing materials.
Roof Drain – Device removing water from roof surface.
Roof Jack – Bracket supporting workers or materials on steep slopes.
Roof Louver – Raised ventilation opening on roof surface.
Roof Pitch – See Pitch.
Roof Plane – Flat sloped surface of a roof.
Roof Sheathing – See Roof Deck.
Roof Slope – See Pitch.
Roof System – Complete assembly providing weather protection.
Roofing Bracket – Temporary support for workers on steep roofs.
Roofing Felt – See Asphalt Felt.
Roofing Hatchet – Specialized tool for cutting and nailing shingles.
Roofing Knife – Hooked-blade knife for cutting roofing materials.
Roofing Nail – Galvanized nail designed for roofing applications.
Roofing Square – See Square.
Rosin Paper – Building paper sized with rosin, sometimes used as underlayment.
Run – Horizontal distance from eave to ridge.
Rust – Corrosion of ferrous metals.
S
Saddle – See Cricket.
Safety Lines – Fall protection equipment for workers.
Sag – Depression in roof surface due to structural deflection or deterioration.
Saltbox Roof – Gable roof with one slope longer than the other.
Sandwich Panel – Insulated metal panel with foam core between metal skins.
Saturant – Asphalt used to impregnate felt in underlayment manufacturing.
Saw-Tooth Roof – Series of ridges with vertical and sloped surfaces.
Scour – Erosion of aggregate or coating by wind or water.
Screw Fastener – Threaded fastener providing enhanced holding power.
Scrim – Open-weave fabric reinforcing membrane laps or serving as base for coatings.
Scupper – Opening through parapet allowing water drainage.
Sealant – Waterproofing compound filling gaps and joints.
Sealdown – Process where asphalt shingle tabs bond to underlying shingle.
Seam – Joint where roofing materials meet.
Seam Plate – Metal plate securing or reinforcing membrane seams.
Seam Strength – Resistance of joined materials to separation.
Seam Tape – Self-adhering tape used with some single-ply membranes.
Seat – Horizontal cut in rafter resting on wall plate.
Secondary Roof – Membrane or barrier beneath primary roofing.
Self-Adhering Membrane – Membrane with integrated peel-and-stick adhesive.
Self-Sealing – Shingles with factory-applied adhesive sealing tabs after installation.
Selvage – Unsurfaced edge of rolled roofing designed for overlapping.
Set – Curing or hardening of sealants and adhesives.
Settlement – Downward movement of building or roof structure.
Shading Coefficient – Measure of solar heat transmission through materials.
Shear Strength – Resistance to forces causing layers to slide.
Sheathing – See Roof Deck.
Shed Roof – Single-plane roof sloping in one direction.
Sheet Metal – Thin metal stock formed into flashings and trim.
Shim – Thin material inserted to level or space components.
Shingle – Individual roofing unit, typically rectangular.
Shingle Butt – Bottom exposed edge of shingle.
Shingle Coverage – Amount of weather protection provided by overlapping shingles.
Shiplap – Joint where one board edge overlaps another.
Side Lap – Overlap between adjacent panels in same course.
Side Wall Flashing – Flashing at junction of sloped roof and vertical wall.
Siding – Exterior wall covering.
Sill – Horizontal member at bottom of wall or window opening.
Single-Ply Membrane – Roofing membrane applied in one layer (TPO, PVC, EPDM).
Skylight – Framed glazed opening in roof providing natural light.
Slag – By-product of metal smelting used as aggregate on built-up roofs.
Slate – Natural stone roofing material known for longevity and beauty.
Slate Hook – Metal device securing individual slate shingles.
Slate Ripper – Tool for removing damaged slate shingles.
Slip Sheet – Separator preventing adhesion between materials.
Slope – Angle of roof surface, typically expressed as ratio or degrees.
Slurry – Thin mixture of cement or coating material.
Smooth-Surfaced Roof – Built-up or roll roofing without aggregate surface.
Snow Bracket – Device holding snow and ice on roof preventing sudden release.
Snow Guard – See Snow Bracket.
Snow Load – Weight of accumulated snow roof must support.
Soffit – Underside of eave overhang.
Soffit Vent – Intake ventilation in soffit area.
Soil Stack – Vertical plumbing drain vent pipe penetrating roof.
Solar Reflectance – Percentage of solar energy reflected by surface.
Solar Reflectance Index (SRI) – Measure combining reflectance and emittance.
Solvent – Liquid dissolving other substances.
Solvent Welding – Joining thermoplastic membranes using solvents.
Spalling – Flaking or chipping of masonry or concrete surfaces.
Span – Distance between structural supports.
Splash Block – Precast concrete block at base of downspout directing water away.
Split – Tear or crack in roofing material.
Sprayed Polyurethane Foam (SPF) – Insulating foam also serving as waterproofing.
Square – Roofing measurement equal to 100 square feet.
Square Butt – Standard rectangular shingle tab design.
Square Tab Shingles – Traditional three-tab asphalt shingles.
Stack – Vertical vent pipe extending through roof.
Stack Effect – Vertical air movement due to temperature differences.
Stair-Stepping – See Racking.
Standing Seam – Metal roofing with raised seams running from eave to ridge.
Starter Course – Initial row of shingles at eaves.
Starter Strip – Material installed at eaves before first shingle course.
Static Pressure – Air pressure in vent system when not moving.
Steel Roofing – Metal roofing panels or shingles made from steel.
Steep-Slope Roof – Roof with slope exceeding 3:12 or 25%.
Step Flashing – Individual metal pieces installed at each shingle course along wall intersection.
Stiffness – Resistance to bending or flexing.
Storm Collar – Cone-shaped flashing sealing around vent pipes.
Straight-Line – Installation pattern where shingles align vertically.
Stress – Force applied to materials.
Stripping – Installing membrane at details before main application.
Structural Panel – Rated sheathing capable of spanning between supports.
Stucco – Cement-based wall finish.
Substrate – Surface to which roofing is applied.
Suction – Negative wind pressure lifting roofing materials.
Sump – Depression in roof collecting water at drains.
Sump Pump – Mechanical pump removing water from roof sump.
Sunbelt – Geographic region with intense solar exposure.
Surface Coating – Protective or decorative layer applied to roofing.
Surface Tension – Molecular force causing liquid surfaces to resist penetration.
Surfacing – Top layer of roofing system exposed to weather.
Synthetic Underlayment – Non-asphalt-based underlayment materials, typically polymer-based.
T
Tab – Exposed portion of strip shingle defined by cutouts.
Tape – Adhesive-backed material for sealing or joining.
Taper – Gradual thickness change in insulation creating slope.
Tar – Dark viscous material from destructive distillation of organic material.
Tar Paper – Historic term for asphalt felt.
Tear-Off – Complete removal of existing roofing down to deck.
Tear Strength – Resistance to propagation of existing tears.
Tee Joint – Junction where one material meets perpendicular to another.
Teflon – Non-stick coating sometimes used on tools and fasteners.
Telegraph – Pattern where roof deck irregularities show through membrane.
Tensile Strength – Maximum stress material can withstand while being stretched.
Termination Bar – Metal bar securing membrane edges at terminations.
Termination – Method of sealing roof membrane at end points.
Terra Cotta – Fired clay product used for tiles and ornamental features.
Test Cut – Sample cut through roof assembly to examine condition.
Thermal Barrier – Material reducing heat transmission.
Thermal Break – Insulating material interrupting thermal conduction path.
Thermal Bridging – Heat transfer through more conductive material in assembly.
Thermal Expansion – Dimensional change due to temperature variation.
Thermal Insulation – Material reducing heat flow through assemblies.
Thermal Movement – Expansion and contraction from temperature changes.
Thermal Resistance – See R-Value.
Thermal Shock – Stress from rapid temperature change.
Thermoplastic – Material that softens when heated and hardens when cooled.
Thermoset – Material that cures irreversibly and won’t remelt.
Through-Wall Flashing – Waterproofing membrane extending through entire wall thickness.
Tie-In – Connection of new roofing to existing.
Tie-Off – Termination of roofing materials at edges or penetrations.
Tile Batten – Wood or metal strip supporting tile roofing.
Tile Roofing – Roofing system using clay or concrete tiles.
Timber – Structural wood members 5 inches or larger.
Tin – Metal once used for roofing, now usually refers to terne-coated steel.
Toggle Bolt – Fastener with spreading wings for hollow substrates.
Tongue and Groove – Interlocking edge joint on decking boards.
Top Lap – Portion of underlayment or membrane covered by next course.
Topcoat – Final protective coating layer.
Torch-Applied – Modified bitumen membrane installation using propane torch.
TPO (Thermoplastic Polyolefin) – Single-ply roofing membrane, heat-weldable.
Traffic Bearing – Roof surface designed for regular foot traffic.
Traffic Pad – Protective pavers at frequently walked areas.
Transition – Area where different roofing materials or slopes meet.
Translucent – Allowing light passage while obscuring view.
Transparent – Allowing clear view through material.
Transverse Seam – Seam perpendicular to roof slope.
Treated Wood – Lumber infused with preservatives.
Trim – Finishing materials at roof edges and transitions.
Truss – Engineered framework supporting roof loads.
Truss Uplift – Vertical movement of trusses from temperature and moisture changes.
Tube – Cylindrical container for sealants and adhesives.
Turbine Vent – Wind-driven rotary exhaust vent.
Turned-Up Edge – Membrane extended vertically at termination.
Two-Part Sealant – Sealant requiring mixing of base and catalyst.
U
UL (Underwriters Laboratories) – Testing organization certifying fire and wind ratings.
Ultraviolet (UV) Radiation – Invisible light causing degradation of roofing materials.
Under-Nailing – Insufficient fastener penetration.
Underlayment – Water-resistant material installed directly on deck under shingles.
Uplift – Upward wind force on roofing system.
Urethane – Polymer used in foams, coatings, and sealants.
U-Value – Measure of heat transmission; inverse of R-value.
V
Valley – Internal angle where two roof planes meet, channeling water runoff.
Valley Flashing – Water-channeling flashing installed in valleys.
Valley Rafter – Diagonal rafter supporting valley.
Vapor Barrier – Material preventing water vapor transmission.
Vapor Retarder – Material slowing but not completely blocking vapor transmission.
Vent – Opening allowing air passage.
Vent Pipe – Plumbing system vent extending through roof.
Vent Stack – See Vent Pipe.
Ventilation – Natural or mechanical air circulation through attic or roof assembly.
Verge – Edge of gable roof overhanging rake.
Vermiculite – Expanded mineral used for insulation.
Vertical Lap – See End Lap.
Vinyl – Synthetic material used in membranes and accessories.
Viscosity – Resistance to flow; thickness of liquid materials.
Void – Gap or holiday in roofing materials.
Volatiles – Materials that evaporate at normal temperatures.
W
Walk Pad – Protective surface for roof traffic areas.
Wall Flashing – Waterproofing at roof-to-wall intersections.
Warranty – Manufacturer or contractor guarantee of performance or workmanship.
Water Cut-Off – Mastic or flashing detail preventing water migration.
Water Infiltration – Water penetration into building assembly.
Water Test – Flooding roof section to verify watertightness.
Waterproofing – Treatment or material preventing water penetration.
Weathering – Material changes from exposure to weather.
Weep Hole – Small opening allowing trapped water to escape.
Weld – Joint created by fusing materials together.
Wide Selvage – Rolled roofing with broad edge for overlapping.
Wind Baffle – See Baffle.
Wind Damage – Roofing failure from high winds.
Wind Load – Force exerted by wind on roofing system.
Wind Resistance – Ability to withstand wind forces without damage.
Wind Uplift – Negative pressure from wind creating suction on roof.
Wind-Driven Rain – Rain propelled by wind into vertical surfaces and beneath roofing.
Wind-Rated – Products tested and rated for specific wind speeds.
Woven Valley – Valley where shingles from both planes interweave.
Wrinkling – Membrane distortion creating folds or ridges.
X
X-Bracing – Diagonal structural members forming X pattern.
Y
Yard – Unit of measurement (3 feet) occasionally used in roofing.
Z
Z-Bar Flashing – Z-shaped metal flashing at horizontal joints.
Zee – Z-shaped metal purlin or closure.
Zinc – Metal used for coating steel or as standalone roofing material.
Zone – Area of roof with specific wind or design requirements.