Roofing Terminology

Adhere: to stick a roof system by means of a construction compound or substance.

Adhesion: the process of sticking to a surface or object

Aggregate: many elements of earth used to improve a roofing systems stability. Often used in built up roof systems as gravel.

Alligatoring: a pattern of cracking on a bitumen roof surface whic looks like an alligator hide.

Asbestos: a heat-resistant mineral that can be made into fabric and used in fire-resistant and insulating materials.

Asphalt Roof Cement: an asphalt based cement used in bonding roofing materials and patch work.

ASTM: international standards organization that develops and publishes voluntary consensus technical standards in the construction industry.

Ballast: heavy material such as rock, stone, etc. to stabilize. Used in holding down a roof system.

Base Flashing: flashing provided by up turned edges of water tight membrane.

Base ply: an asphalt-saturated or coated felt that is installed as the first ply in a roof system.

Base Sheet: a filled in or coated felt placed as the first ply in some low-slope roof systems.

Batten: a long, flat strip of squared wood or metal used to hold something in place or as a fastening against the wall.

Batten Seam: used to provide the fixing point for roofing materials such as shingles or used in metal roofing to secure the sheets

Bitumen: a black mixture of hydro carbons obtained naturally or as a residue from petroleum distillation.

Blender Strip: a strip of asphalt material along the rake over an unseen drip edge of metal.

Blind- Nailing: the use of nails that are not exposed to the weather.

Blister: moisture trapped underneath a layer of roofing causing bubbles to form in the roof surface.

Blocking: any use of wood on a roof surface either for pipe type supports or perimeter edging.

Brake: machine or hand powered equipment to bend metal into a form. Typically used to bend coping or gutter.

Brooming: using a broom or squeegee to improve the embedding of the membrane in adhesive.

Buckle: when the metal plates in coping or other roof conditions come together and cause a reaction in which none fit or bend upward.

Built-up Roofing Membrane: semi-flexible membrane consisting of multiple plies of saturated or coated felts of asphalt. Surfaced with liquid-applied roof coating.

Cant Strip: a strip placed in the angle between a roof and a wall to avoid a sharp bend in the roofing material.

Cap Sheet: a sheet used as the top ply of some membranes and modified bitumen roof systems.

Capillary Action: the movement of water within the spaces of a material due to adhesion, cohesion, as well as surface tension.

Caulk: to close or seal in seams, crevices, cracks, joints, etc.

Cavity Wall: a wall built to provide space within, tied together by framing.

Channel Flashing: a type of flashing used at roof-to-wall junctures as well as roof-to-wall verticals. Profile tile is often used.

Cladding: exterior wall enclosure often made of metal.

Cleat: metal strip either continuous or individual and are used to secure two or more pieces of metal together.

Clip: a single cleat or piece to hold something together.

Coping: covering piece on top of wall exposed to weather made of metal, masonry, or stone. Sloped so water goes back onto roof.

Counterflashing: metal sheeting on or into wall to cover or protect the edge of the membrane flashing or metal flashing underneath.

Cricket: diverts water around a chimney, curb, or away from the wall.

Cross Ventilation: air moving through roof cavity between vents.

Curb: used to support roof penetrations, sky lights, mechanical equipment, hatches, etc.

Deck: supports dead and live loads. Huge component. Decks are either made with metal, some version of concrete or wood. Provides substrate for a water proofing system to be applied to.

Deflection: downward movement in the deck or system under load.

Degradation: a change in the chemical structure, physical, or appearance of the material due to natural or artificial exposure.

Delamination: laminated layers separated or often times when membrane wall flashings come off of the wall itself.

Design Loads: loads specified in building codes published by federal, state, city, or owner specifications to be used in the building design.

Drain: an outlet or device used to collect the flow of water from a roof.

Eave: edge of roof that extends beyond the supporting wall.

Edge Stripping: flashing strips of membrane cut and used to seal perimeter edge metal and membrane.

Elasticity: an object or material has this when it returns to the same shape after stress altered its form.

Elastomer: material that can be stretched at room temp. Shape altered with little amount of stress and returns very quickly.

Elastomeric: elastic, rubber like, stretched when pulled and return back to normal quickly after being let go.

Electrometric Coating: a coating system that is capable of being stretched at least twice its original length.

Elongation: a materials ability to be stretched by force.

Embedment: process of installing reinforcement felt, into bitumen.

Emulsion: the dispersal of fine particles into a liquid.

End Lap: distance where one ply piece extends beyond the end of the other ply of material. One roll ends then the next covers the pre-existing piece.

EPDM: an extremely durable rubber roofing membrane used on low-slope buildings sealed with liquid adhesives at the seams with seam tape. Often black in color.

EVT: the temperature at which a bitumen has the proper viscosity for membrane application.

Expansion Cleat: cleat or formed piece of metal designed to deal with thermal movement between metal roof panels or edge metal joints.

Expansion Joint: designed to safely absorb thermal expansion from roofing materials because of temperature increasing or decreasing or building movement.

Exposed-Nail Method: method in which nails are driven into the overlapping course of roofing which allows the nails on the roof to be exposed to the weather.

Fabric: cloth, organic material, inorganic filaments, threads, or yarn used for reinforcement in certain membranes and as well as flashings. Or used as a separation layer slip sheet between roof systems.

Factory Mutual Research Corporation: a research and testing organization that classifies roofing materials for their fire, traffic, impact, weathering, and wind up-lift resistance for several major insurance companies in the US.

Fascia: a type of edge metal in roofing, usually a border for low slope roofing systems that waterproofs the interior portions of the building and creates an end cap.

Fasteners: a wide variety of mechanical securement devices as well as assemblies, these include nails, screws, clips, and bolts, which could also be used to secure several components of a roof during assembly.

Feathering Strips: wood filler strips placed along the butt ends of old wood shingles to create a smooth surface when roofing over pre-existing wood shingle roofs. ‘Horse feathers’ in other parts of the country.

Felt: sheet made by interlocking fibers through several processes of mechanical work, moisture, and also heat. Made from wood pulp, vegetable fibers, asbestos fibers, glass fibers, and polyester fibers. Used often as an underlayment sheet or slip sheet.

Felt Machine: device that is used for applying bitumen and roofing felt or ply sheet at the same time.

Ferrule: small metal sleeve inside the top of a gutter. Nailed by a spike through the gutter to keep it in place. The ferrule is used to as a spacer in the gutter to maintain its original shape.

Field of the Roof: main portion of the roof, excluding the perimeter and flashing.

Field Seam: splice or seam that is made on the job site in which overlapping sheets of roofing material are joined together using tape, adhesive, and even welding.

Fine Mineral-Surfacing: does not mix with water, used on the surface of various types of roofing and membranes to prevent sticking.

Fire Resistance: the buildings ability to act as a barrier to the spreading of fire and make sure it stays in the area of origin.

Fishmouth: half-conical shaped opening or void in a lapped edge or seam, caused by wrinkling or shifting of ply sheets during installation.

Flaking: uniform layer of coating or surface material being detached from the roof system, usually because of internal movement, lack of adhesion, or because of moisture.

Flame Retardant: substance that is added to polymer formulation to reduce the tendency of the roofing material to burn.

Flammability: a materials characteristics to burn or even support combustion.

Flange: the edge of a rigid component such as a metal edge, flashing, skylight, flashing boot, or structural member.

Flash Point: the lowest possible temperature that a liquid gives off vapor to be able to ignite with air near the surface. Roofing bonding adhesives need to hit a flash point before materials can be fully adhered together.

Flashing: material used to weather proof or seal the roof system at perimeters, penetrations, walls, expansion joints, valley, drains, and etc. A separate piece of roofing material is used.

Flashing Cement: mixture of solvent-based bitumen and mineral stabilizers that may include asbestos as well as possibly inorganic or organic fibers. This type of cement is intended and generally used for use on vertical surfaces or built up roof patches.

Flashing Collar: flashing that is an accessory used to cover or seal pipe vents and other penetrations or holes in the building’s roof.

Fleece: felts or mats made with fiber. It is often used as a membrane backer.

Flood Coat: the layer on the surface of bitumen in which the surface aggregate is embedded on the built-up roof. It is generally thicker and heavier than glaze coats and is applied at 45-60 pounds per square. A poured in place layer of hot asphalt on a roof.

Flood Test: procedure in which a controlled test takes place with a certain amount of water to test the effectiveness of the roof being water proofed. Often using a hose and ‘plugging’ roof drains.

Fluid-Applied Elastomer: liquid material that after application forms a continuous waterproofing membrane.

FM: Factory Mutual

Gable: a triangular portion of a building that is directly under the sloping roof and above the eave line.

Gable-Shaped Roof: a single-ridge that stops at the end of the gable.

Galvalume: name for coating used over metal that is made of aluminum zinc for protection from corrosion.

Galvanic Action: a reaction between dissimilar metals when near an electrolyte.

Galvanize: to coat a material with zinc.

Galvanized Steel: steel that is coated with zinc for protection against corrosion.

Gambrel: two pitches on each side of the roof.

Gauge: measurement of the rating of thickness for metal.

Glass Felt: sheet made of glass fibers bonded together suitable for coating in manufacturing of bituminous roofing as well as water proofing materials.

Glaze Coat: a thin protective membrane that is applied to the lower plies when applying additional felts or the flood coat are delayed.

Granule: natural, opaque, or synthetically colored tiny grit rock used to surface cap sheets, shingles, and other surfaced roof coverings.

Gravel: natural erosion of rock. Used in built up roof systems as a surfacing.

Gravel Stop: low profile upward projecting metal flashing that has flange along the roof usually from extruded metal or another sheet. Installed along the edge of the roof to provide a finished edge. Also is used to stop bitumen during mop application of hot bitumen along the edge or stop gravel from falling off on a gravel surface roof.

Gutter: component installed along the downslope of a roof to transport water from the roof to the downspouts.

Headlap: the distance of overlap measured from the highest ply or course to the point that it overlaps the lowest ply.

Heat Welding: melting and fusing the overlapping edges of separate sheets of polymer bitumen, thermoplastics, or some roofing membrane by being assembled by heat and force.

Hem: edge created by folding the sheet of metal back onto itself.

Hip: external angle that is inclined and is formed by intersections between two sloping roof planes.

Hip Roof: a roof that is rising because of inclined planes to form one or more hips.

Hoist: a lifting device used by the worker.

 “Hot” or “Hot Stuff”: a term used by roofers to describe hot bitumen.

Humidity: the amount of moisture in the atmosphere usually calculated by percentage.

HVAC: heating, ventilating, and air conditioning.

Hydration: chemical reaction by which a substance combines with water producing heat to form a crystalline structure in its place.

Hypalon: a trademark for E.I DuPont de Nemours.

ICBO: International Conference of Building Officials. The author of what is known as the Uniform Building Code.

Impact Resistance: the roofing membranes ability to resist damage from objects falling, equipment application, foot traffic, etc. impact resistance of the roofing assembly is a function that is of all the components and not just the membrane.

Incline: slope of roof either in percent or in number that is displayed in a percentage. Vertical units rise per horizontal units.

Inorganic: any material chemical compound that is made from minerals that does not contain carbon, and is not in the same class as organic compounds. Not made of plant or animal origin.

Insect Screen: wire mesh that is used to prevent insects from entering the building through areas that are hard to reach for humans.

Insulation: any material that is designed to reduce the flow of heat from inside or into the building. ‘Polyiso’ is an example for roofing.

Intake Ventilation: fresh air that is passed into a ventilation system through vents installed in the edges of the roof.

Interlayment: felt, metal, or even membrane material used between courses of steep-slope roofing. Improves the weather and water shedding characteristics of the roof covering. Typically used for wood shakes.

Interlocking Shingles: shingles that are attached to each other to provide resistance to wind.

Internal Pressure: pressure that is inside the building that helps ventilating equipment, wind velocity, and also the number of openings and air leaks.

Joist: small beams either made of wood or metal arranged from one wall to another to support the floor, ceiling, or the roof of a building.

Laminate: the bonding of two or more layers of material together.

Laminated Shingles: a shingle made of multiple layers stuck together to give the visual impression of wood.

Lap: part of the roofing, water proofing, and flashing that overlaps and or covers any portion of the same type of component.

Lap Cement: an asphalt-based roof material made to stick to overlapping plies or asphalt roll roofing.

Lap Seam: occurs when overlapping materials are seamed, sealed, and or otherwise sealed or bonded together.

Latex: dispersion of a polymer in water and forms into a film once evaporation of water takes place.

Lead: soft metal used for flashing. Often used in built up roofs or mod bit roofs.

Leader Head: Sometimes referred to as a conductor head usually attached at the edge of the roof and is used to connect gutters. Used to capture storm runoff water on top of the roof.

Life Cycling Costing: a method of analysis economically in which it takes into account costs over the life of an asset.

Lift: sprayed foam that results from a pass. Usually associated with pass thickness and has a bottom layer, center of mass, and top skin.

Light Reflectance: percentage of light that is not absorbed by the materials surface.

Live Loads: loads that are only temporary and the roof must be designed to support the load. They are usually moving and do not stay on the field for long.

Load Deflection: displacement of a member or system under load.

Loose-laid Membranes: membranes that are not fastened for adhered except at the perimeter of the roof as well as penetrations. They are usually loose-laid and are held in place with weight or ballast, such as gravel, stone, etc.

Low Temperature Flexibility: the ability of a membrane or a material to stay flexible after it was cooled to a low temperature.

Mansard: a roof that is steep, decorated, and on the perimeter of the building.

Mansard Roof: steeper roof that then goes flat at its highest point.

Masonry: any material constructed as bricks, stone, concrete blocks, ceramic blocks, as well as concrete.

Mastic: a mixture of bitumen, mineral stabilizers, as well as other fibers and fillers.

Mat: thin layer of woven, non-woven, or even knitted fibers that reinforce the material or the membrane.Often seen as a felt mat.

Material Safety Data Sheets: written descriptions of chemicals in a product and other data including such things as safety and emergency procedures. In accordance to OSHA it is the manufacturer’s responsibility to communicate the contents to employees.

Mechanically-Fastened Membranes: generally used to describe membranes that are attached at defined locations or intervals. Fastening may be performed with various fasteners and other mechanical devices, such as plates or battens in the membrane sheets.

Membrane: a flexible or semi-flexible material, which functions as the waterproofing roof covering, and its primary function is the exclusion of water. Examples are TPO, EPDM, KEE and PVC.

Metal Flashing: components fabricated from sheets of metal used to weather proof the roof and the edges as well. Used most of the time as coping, counterflashing, step flashing, etc.

Migration: absorption of oil from a compound into a porous surface.

Mil: unit of measurement one mil is equal to 0.001 inches or 25.400 microns, often used to measure thickness of a roofing membrane.

Mildew: a coating that is superficial and made of organic material. Also has a discoloring because of fungal growth.

Millimeter: unit of measurement that is equal to one thousandth (0.001) of a meter, or it is in inches equal to 0.03937.

Mineral-Surfaced Sheet: roofing sheet that’s coated on either sides or one with asphalt and mineral granules.

Miter: joint made when connecting two diagonal pieces. Often a metal edge detail like coping or gravel stop.

Moisture Scan: the use of mechanical devices to detect moisture within the roofing assembly.

Mole Run: buckle or ridging in a roofing membrane that is not associated with insulation or deck joints.

Monolithic: formed from a single material or composed and is also seamless.

Monomer: simple molecule that’s capable of combining with other materials to form a polymer with like and unlike numbers.

Mopping: the appliance of hot bitumen with a hand mop or mechanical device to the substrate or felts of a bituminous membrane.

Solid Mopping: continuous mopping of any surface.

Spot Mopping: mopping pattern that is applied in different areas leaving certain spots un-mopped.

Sprinkle Mopping: random mopping patterns in which heated material is strewn onto a substrate with a brush or mop.

Strip Mopping: mopping pattern that applies hot bitumen in parallel bands.

Nailer: piece or multiple pieces of dimensional lumber or plywood secured to decks and walls to provide a medium for fasteners to attach the membrane or flashing. Should all be the same thickness.

Nailing: the process by which nails are applied to the material. Exposed nailing is when the nail heads are exposed while concealed nailing is when the nail heads are not exposed and are concealed.   

Neoprene: rubber that is synthetic and used in liquid and sheet applied elastomeric roof membranes. Other examples are using neoprene washer screws for sealing screws.

Non-Destructive Testing: testing that is typically used to evaluate moisture content. Three methods include the following; electrical capacitance, infrared thermography, and nuclear back-scatter.

Non-Flammable: material that is not combustible.

Non-Friable: materials that when dry cannot be crumbled or have its shape changed by pure hand pressure.

Non-Traffic Bearing: water-proofing purposes requiring some protection barrier as well as wearing surface.

Open Valley: valley construction in which the steep-slope roofing on both sides of the building are trimmed on each side exposing the flashing.

Organic: composed of hydrocarbons that have originated from plant or even animal matter.

Organic Felt: asphalt roofing material that is made from cellulose fibers.

Organic Shingle: an asphalt shingle made with material known as cellulose fibers.

Ozone Resistance: the materials ability to resist effects caused by exposure to deteriorate.

Pallet: a wooden or even metal platform that is used for storing as well as shipping materials.

Pan:  often another term for a metal decking layer beneath a lightweight concrete deck system.

Parapet Wall: the perimeter wall that is immediately adjacent to the roof that extends above the roof.

Penetration: any object that is passing through a roof that leads to there being a hole.

Percent Elongation: testing in which to increase the length and determine how the material held against a fracture.

Perlite: light weight insulation made for insulating boards, it is made by heating and expanding siliceous volcanic glass.

Permeability: capacity of porous material to be able to transmit or allow fluids, the amount of fluid moving through a barrier, and related to thickness.

Phased Application: installation of roof system or waterproofing during two or more phases. Application of different surfaces done at different times.

Picture Framing: square or rectangular pattern of buckles and or ridges in a roof covering that is generally followed by insulation or deck joints.

Pigment: solid particles that are insoluble and used to impart color in the coating.

Pinhole: a tiny hole in coating, film, foil, laminate, and even membrane.

Pipe Boot: flashing piece that is prefabricated and used around circular pipe penetrations in roofing.

Pitch-Pan: flanged open bottomed closure that is made of sheet metal or other material, placed around the penetration through a roof, filled with sealants to seal around the actual penetration.

Plastic Cement: roof cement that is a mixture of bitumen, mineral stabilizers, and other fibers as well as fillers. Intended use on low slopes and vertical services for repairs of asphalt roof surfaces.

Plastic Film: flexible sheet that is made by an extrusion of thermoplastic resins.

Plasticizer: material that is most of the time solvent-like, in a plastic or rubber to increase the ease of workability, flexibility, and or extensibility.

Pliability: material property that is flexible or as well as moldable.

Ply: layer of felt, ply sheet, or reinforcement in a roof membrane or roof system.

Polyester Fiber: synthetic fiber usually formed by extrusion. Polyester fibers are used for fabric reinforcement.

Polymer: natural synthetic chemical compound of high molecular weight, or a mixture of compounds when monomers are combined to form large molecules.

Polymerization: process whereby monomers are combined to form larger molecules.

Polypropylene: tough, lightweight plastic made by polymerization

Ponding: the accumulation of water on low-lying areas on the roof.

Pop Rivet: a small pin with an expandable head that joins light metal.

Positive Drainage: drainage in which the roof is built so that there is water flow from the roof within 48 hours.

Pourable Sealer: the type of sealant that is used to seal formed pitch-pockets.

Pre-Tinning: coating a metal before soldering or brazing the metal.

Press Brake: a machine that is used in forming sheets of metal or strips into desired profiles. Examples – coping, gravel stop, cleat, etc.

Primer: a thin liquid solvent that is applied to a surface to improve the adhesion of applications. Sometimes used in the process of single-ply membranes to surfaces and increases the strength of the membrane adhesion.

Puncture Resistance: the extent in which a material is able to hold or withstand a sharp object that halts penetration.

Purlin: secondary structure that is horizontal and transfers loads from the structural framework that is primary to the building.

PVC: Polyvinyl Chloride, a type of roofing membrane.

R-Value: the resistance of heat being transferred to a material.

Rafter: a series of sloped beams that extend from the ridge or hip to the downslope and is designed to support the roof deck and its loads.

Rake: the sloped edge of a roof that is adjacent to the first or the last rafter.

Rake-Starter: the starter-strip used along the rake edges that are in conjunction with the asphalt shingle roofing.

Re-Cover: the addition of a roof membrane over a pre-existing roof assembly. The process does not include removal of the current roof.

Reflectivity: a materials ability to reflect light.

Reinforced Membrane: roofing or waterproofing membrane that is strengthened by the addition of one or more reinforcing materials that include woven or nonwoven glass fibers,

Relative Humidity: ratio of weight and moisture given volume of air-vapor mixture and the weight of water vapor at the same temperature. It is expressed in the form of a percentage.

Replacement: the removal of an existing roof system all the way down to the roof deck and replacing it with an entirely new roofing system.

Reroofing: process of re-covering or tearing-off an existing roof. Replacing an existing roof system.

Resin: component contains a blowing agent, fire retardants, surfactants and polyol.

Thermal Resistance: the temperature difference between two surfaces of a body/material.

Ridge: highest point of the roof.

Ridge Cap: covering that is applied over a ridge of a roof.

Ridge Course: the last or the top course of roofing materials, such as tiles or shingles that covers the ridge and overlaps the intersecting field roofing.

Ridge Vent: ventilator located at the ridge that allows the escape of warm and cold air from the attic.  

Roll Goods: a term applied to roofing rolls such as felt, ply sheets, etc.

Roll Roofing: smooth-surfaced, coated, or prepared felt sheets. Most often modified bitumen sheets.

Roof Assembly: assembly of interacting roofing materials such as roof deck, vapor barrier, insulation, and roof covering.

Roofer’s Cement: sealant that is used to waterproof the main projections of the roof on asphalt roof systems.

Roof Covering: roof covering of the exterior made up of membrane, panels, sheets, and shingles as well.

Roof Curb: a raised frame that is used generally for mechanical devices such as exhaust fans or skylights.

Roof Overhang: a roof that projects over the wall of the building and is used to throw water clear from the buildings walls.

Roof Slope: often referred to as the pitch and is measured by inches from the vertical rise to the horizontal length.

Roofer: a worker who constructs or repairs roofs.

Rosin-Sized Sheathing Paper: 100% recycled paper that is used for the underlayment of flooring and siding it is also used temporarily to protect work site construction.

Saddle: a roof that forms a convex curve that is in the shape of a saddle.

Sag: bending or hanging down in the middle of the structure due to weight or weakness in the material.

Saturated Felt: base material that is used to produce roof shingles and roll roofing. Underlayment of other roofing materials and is one type of membrane that is used in asphalt built up roofing.

Scrim: a heavy coarse woven material that is used for reinforcing a membrane.

Sealant: a fluid that is applied to roofing membranes that have elastic properties which allows it to stretch and return to its original form without any harm.

Seam: area in which 2 layers of membrane are sealed together or 2 metal panels are joined.

Seam Strength: strength of a garment or material used to hold together the product.

Self-Adhering Membrane: a membrane that can adhere by itself to another surface. Also this material is protected by release paper.

Self-Drilling Screw: drill and taps own hole during the process of application.

Self-Sealing Shingle: a shingle made of asphalt with factory applied strip that applies itself to the roof once it is heated by the sun.

Self-Tapping Screw: a screw that can tap its own hole as it goes deeper into the material.

Shear Strength: stress that is required to disrupt a seam or bonded joint

Shed Roof: roof that contains a sloping plane that has no hips, ridges, or valleys.

Sheet Metal Flashing: used to protect certain areas on a roof such as joints and angles. Used especially for leaking problems.

Shingle: individual unit of roofing material that is designed to overlap rows at an incline.

Shingling: the application of shingles. The procedure of applying the shingles is done longitudinal so each shingle or felt overlaps as well as underlaps one another. Done at a downslope due to runoff water flowing over the felts rather than against.

Shrinkage Crack: a crack often due to loss of water because of evaporation.

Siding: exterior wall finish material that is applied to a light wood structure.

Silicone-based Water Repellants: applied to masonry materials for damp proofing or repelling water.

Sill: the bottom horizontal framing member of an opening such as a door.

Sill Flashing: flashing that is horizontal to the opening at the bottom.

Single Coverage: roofing material that provides one layer over the substrate to which it is applied.

Single-Ply Membranes: roofing membranes that are field applied using just one layer of membrane material rather than multiple layers.

Single-Ply Roofing: a roofing system in which the principal roof covering is a single layer flexible membrane.

Single-Ply System: six types that include loose laid, fully adhered, mechanically fastened, partially adhered, protected membrane, and self-adhering.

Slag: a hard, air cooled aggregate that is a residue from blast furnaces

Slate: a hard brittle rock consisting mainly of clay materials used for steep roofing and granular surfacing on other roofing materials.

Slating Hook: a steep slope roofing attachment device that is in the shape of a hook that can be used for fastening roof slate.

Slip Sheet: sheet material placed between two components of a roof assembly to ensure that no adhesion or damage occurs between

Smooth Surfaced Roof: a roof that does not have mineral granules or aggregate surfacing on it.

Snap-On Cap: a cap that snaps on over vertical legs of the standing seams in metal roofs or even the batten seam of metal roof systems.

Soffit: the underside of an overhang in a roof that is closed off.

Soffit Vent: a premanufactured or custom built air inlet source that is located on the downslope or in the soffit or the roof assembly.

Softening Point: the temperature at which the bitumen becomes soft enough to flow.

Solder: a tin mixture with lead that is melted and used to bond two pieces of metal together.

Solvent: liquid used to dissolve or disperse film that is forming and when it dries it does not leave a film after everything is evaporated.

Specification: requirements for a specific job or project. Usually involves products, materials, and the processes in which they are to be used. Also could include details in a contract.

Splash Block: a small block laid on the ground or lower roof below the opening of a downspout used to help prevent soil erosion and aggregate scour in front of the downspout. 

Splice: bonding or joining of materials overlapping.

Splice Plate: a metal plate placed underneath the joint between two metal plates.

Splice-Tape: synthetic rubber tape used for splicing membrane materials.

Split: a tear in a material or membrane resulting from force.

Split Slab: two separate concrete slabs such as a suspended slab, and covered with waterproofing and a drainage system.

Sprayed Polyurethane Foam (SPF): foamed plastic material, formed by spraying two components to form a rigid water resistant membrane.

Sprinkle Mopping: applying hot bitumen by mechanical or hand application.

Spunbond: non-woven fabric formed from continuous fiber filaments that are laid down and bonded continuously.

Square: 100 square feet.

Square-Tab Shingles: shingles with tabs that are all the same size as well as exposure.

Standing Seam: a metal roof system that consists of overlapping or interlocking seams that occur at an upturned rib. Made by turning up edges of two adjacent metal panels and overlapping them, then folding or interlocking them.

Starter Course: the first layer of roofing, applied to the downslope of the roof area.

Starter Sheets: felt, ply sheet, or membrane strips that are made or cut to widths narrower than the standard width of the roll, used to start the shingling pattern at an edge of the roof.

Starter Strip: roll roofing or shingle strips applied along the downslope eave line, before application of the first course of roofing, intended to fill in spaces between cutouts and joints.

Static Load: any load on a structure that does not change in magnitude or position with time.

Steel Joist: normally used as a horizontal supporting member between beams that are suitable for the support of some roof decks.

Steep Asphalt: a mixture of solvent based- bitumen, mineral stabilizers, or other fibers.

Steep-Slope Roof: a roof of suitable slope to accept the application of water shedding materials.

Steep-Slope Roofing: a category of roofing that includes water shedding types of roof coverings installed on slopes exceeding 25%.

Steeple: a tower or spire, usually located on a church.

Step Flashing: individual pieces of material used to flash walls, around chimneys, dormers, and such projections along the slope of a roof. Individual pieces are overlapped and stepped up the vertical surface.

Strain: expression for the elongation of a material under stress. Strain is expressed as the ratio of elongation per unit length.

Strapping: method of installing roofing rolls or sheet good materials parallel with the slope of the roof.

Straw Nail: a long nail that is used for fastening over tile at the hips and or ridges.

Stress: internal resistance of a material to a force, measured as a force per unit area.

Stress-Crack: either external or internal cracks within a material.

Strike-Through: term used for manufacturing polymeric sheeting to indicate layers that have made bonds through contact.

Strip Mopping: application of hot bitumen to felts of a membrane.

Strip Shingles: asphalt shingles that are manufactured in strips, and are three times longer than they are wide.

Structural Panel: a panel designed to be applied over open framing in which a structural deck will not be required.

Styrene Butadiene Styrene Copolymer (SBS): high molecular weight polymers that have both thermoset and thermoplastic properties, formed by the block copolymerization of styrene and butadiene monomers. Used as the modifying compound to make asphalt membranes have a more rubber-like quality.

Substrate: the surface upon which the roofing or waterproofing membrane is applied.

Sump: international depression around a roof drain or scupper that promotes drainage.

Surface Erosion: the wearing down of a surface due to abrasion, dissolution, or most commonly weathering.

Surfacing: the top layer of roof covering, designed to protect the underlying roofing from direct exposure of weather.

Synthetic Rubber: several elastic substances resembling natural rubber mainly used in fabrication of single-ply roofing membranes.

Tab: exposed portion of strip shingles defined by cutouts.

Tapered Edge Strip: insulation strip used to elevate the roof as well as cause a slope at the perimeter as well as provide gradual transition from one layer of insulation to another.

Tar: brown or black material that is liquid while also being semi-solid. It is made by condensing coal, petroleum, oil-shale, wood, and other organic materials.

Tar Boils: moisture caught in bubbles from the tar.

Tear-Off and Reroof: the removal of all roof system components down to the structural deck, followed by installation of a completely new roof system.

Tear Resistance: the load required to tear a material, when the stress is concentrated on a small area of the material by the introduction of a prescribed flaw or notch.

Tear Strength: the maximum force required to tear a specimen.

Tensile Strength: the maximum force a material can bear without tearing or breaking apart.

Termination: the treatment or method of anchoring and or sealing the free edges of the membrane in a roof or waterproofing system.

Terra Cotta: low-fired clay, either glazed or unglazed.

Thatch Roof: the covering of a roof usually made of straw, reed, or natural foliage bound together to shed water.

Thermal Barrier: a material applied over foam designed to slow the temperature rise of the foam during a fire and delay its involvement in the fire. Thermal barriers for use with SPF must have a time rating of not less than 15 min.

Thermal Insulation: a material applied to reduce the flow of heat.

Thermal Shock: temperature changes in a roof membrane between hot and cold weather that forces the membrane to contract rapidly.

Thermal Stress: change due to temperature change in a structure that is contained against expansion or contraction.

Thinner: a liquid used to reduce the viscosity of coatings or mastic. Thinners evaporate during the curing process. Thinners may be used as solvents for cleanup of equipment.

Through-Wall Flashing: a water resistant material, which may be metal or membrane extending through a wall and its cavities, positioned to direct water entering the top of the wall or cavity to the exterior, usually through weep holes. 

Tongue and Groove Planks: one of the oldest types of dimensional structural wood used as roof decking. The sides are cut with convex and concave grooves so adjacent planks may join in alignment with each other to form a uniform roof deck.

TPO: Thermoplastic Polyolefin.

Traffic Bearing: in waterproofing, a membrane formulated to withstand a predetermined amount of pedestrian or vehicular use with protection and a wear course.

Ultraviolet (UV): wavelengths of visible light and are just beyond the violet end.

Underlayment: asphalt-saturated felt or other sheet material installed between the roof deck and the roof system, usually used in a steep-slope roof construction. Underlayment is primarily used to separate the roof covering from the roof deck, to shed water, and to provide secondary weather protection for the roof area of the building.

Underwriters Laboratories, Inc. (UL): an organization that tests, rates and classifies roof assemblies for their resistance to: fire, impact, leakage, corrosion of metal, and wind uplift.

Valley: internal angle that is formed at the intersection of two sloping roof planes.

Vapor Retarder: material installed to impede or restrict the passage of water vapor through a roof assembly.

Vent: opening designed to convey air, heat, water vapor or other gas from inside a building component to the atmosphere.

Ventilation Short Circuit: occurs when air is in the ventilation system from an area higher than the intake vent thereby minimizing or defeating the effectiveness of the intake vent.

Ventilator: accessory designed to allow the passage of air.

Void: an open space or break in consistency. Often a gap in membrane seam seals.

Vulcanization: various processes which natural or synthetic rubber materials are cured or treated to render non thermoplastic, improves their elastic and physical properties.

Water Absorption: the amount of water absorbed by a material after immersion for a period of time. Might be expressed as a percentage or weight.

Water Cure: method of curing material such as concrete by applying mist over the surface to control the rate of moisture evaporation from the material.

Wear Course: top layer of surfacing that carries pedestrian or vehicular traffic.

Weather Infiltration: negative condition where rain or snow penetrate the roof. Typically is due to wind.

Weep Holes: small openings that permit drainage of water that builds up inside a building component.

Weld: to join pieces of metal together by heat fusion.

Wicking: the process of moisture movement by capillary action rather than movement of water vapor.

Wind Load: force exerted by the wind on a structure or part of a structure.

Wind Uplift: force caused by the deflection of wind at roof edges, roof peaks or obstructions, causing a drop in air pressure immediately above the roof surface. This force is then transmitted to the roof surface. Can cause the membrane to balloon and pull away from the roof.

Wire Tie System: a scheme of attachment for steep-slope roofing units with wire to be used as concealed fasteners.

Woven Valley: method of valley construction in which shingles or roofing from both sides of the valley extend across the valley and are woven together by overlapping alternate courses as they are applied.

Zinc: a metal that has application considerations including high expansion-contraction rates and low temperature restrictions.