Glossary of Common Roofing Terms:

 

 

 

AAMA:  American Architectural Manufacturers Association

           

Absorption: The act or process of retaining foreign particles such as gas or liquid without transmission of these particles.

           

ACI: American Concrete Institute           

 

Acid Etch: (1) The use of a strong acid to remove the surface of concrete thereby exposing the aggregate. (2) The use of a strong acid to etch the surface of material such as metal in order for that material to accept a primer or Spray Polyurethane Foam.

           

ACIL: American Council of Independent Laboratories

           

Acrylic Coating: A coating system with an acrylic resin base.    

 

Acrylic Resin: Polymers of acrylic or methacrylic monomers often used as a

latex base for coating systems.

 

Active:  Will corrode in the presence of moisture or a "noble" metal.       

 

Adhere: The clinging of one surface to another; either molecularly or otherwise.  

 

Adhesion: The state of adhering           

 

AFA: American Fiberboard Association 

 

AGC: Associated General Contractors of America          

 

Aggregate: A surfacing material or ballast for a roof system. Aggregate can be rock, stone, crushed stone or slag, water-worn gravel, crushed lava rock or marble chips.         

 

AHA: American Hardboard Association 

 

AIA: American Institute of Architects     

 

Air Blown Asphalt: Asphalt produced by blowing air through molten asphalt held at an elevated temperature. This procedure is used to modify properties of

the asphalt.      

 

Algae discoloration: Type of roof discoloration caused by algae. Commonly called fungus growth.       

 

Alligatoring: The cracking of the surfacing bitumen on a built-up roof, producing a pattern of cracks that resemble an alligator’s hide. <picture>          

 

Aluminized Steel: Sheet steel with a thin aluminum coating on the surface to enhance the steel’s ability to withstand weathering.      

 

Aluminum: A non-rusting metal used in roofing for metal roofing and the fabrication of gutter and flashings.      

 

Ambient Temperature:  The temperature of the air.        

 

Anodic: When two metals are connected in an electrolyte, they will form a galvanic cell, with the higher metal in the galvanic series being the anode. The anodic will oxidize and produce an electrical current which protects the cathode from corrosion.           

 

ANSI: American National Standards Institute      

 

APA: American Plywood Association    

 

APP: See Atactic Polypropylene.          

 

Application Rate: The rate at which a material is applied per unit area.    

 

Apron Flashing: A flashing located at the low end of a curb or penetration.       

 

Architectural Panel: A metal roof panel that usually requires solid decking underneath.   

 

Architectural Shingle: Shingle that provides a dimensional appearance. See also Dimensional Shingle.  

 

Area Divider: A flashed assembly usually extending above the surface of the roof that is anchored to the roof deck. It is used to relieve thermal stresses in a roof system where an expansion joint is not required, or to separate large roof areas.       

 

ARMA: Asphalt Roofing Manufacturers Association       

 

ASA: American Subcontractors Association      

 

Asbestos: An incombustible fibrous mineral form of magnesium silicate formerly used for fireproofing and sometimes used for the reinforcement of roofing materials.         

 

ASC: Associated Specialty Contractors 

 

ASHI: American Society of Home Inspectors     

 

ASHRAE: American Society of Heating, Refrigerating & Air-Conditioning Engineers, Inc. 

 

Asphalt: A substance left as a residue after evaporating or otherwise processing crude oil or petroleum. Asphalt can be refined to conform to various roofing grade specifications         

 

Asphalt Emulsion: A mixture of asphalt particles and an emulsifying agent such as bentonite clay and water.     

 

Asphalt Felt: An asphalt-saturated and/or an asphalt-coated felt membrane. (See also Felt.)       

 

Asphalt plastic roofing cement: Asphalt-based cement used to bond roofing materials. Also known as flashing cement or mastic; should conform to ASTM D-4586.         

           

Asphalt shingle: A shingle manufactured by coating a reinforcing material (felt or fibrous glass mat) with asphalt and having mineral granules on the side exposed to the weather.     

 

ASTM: American Society for Testing and Materials        

 

Atactic Polypropylene: A group of high molecular weight polymers formed by the polymerization of propylene.  

 

Attic: The open area above the ceiling and under the roof deck of a steep-sloped roof.   

 

AWPA: American Wood Preservatives Association        

 

AWS: American Welding Society           

 

Back surfacing: Fine mineral matter applied to the back of shingles to keep them from sticking to one another before application.      

 

Base flashing: That portion of the flashing attached to or resting on the deck to direct the flow of water onto the roof covering.         

 

Battens: 1"x2"x4' wood strips nailed to the roof, upon which the field tile hangs. 

 

Bird stop: In addition to preventing birds from nesting in the hollows of the tile, this length of formed metal or foam elevates the first course of tile so that it is positioned at the same angle as subsequent courses. 

 

Blisters: Bubbles that may appear on the surface of asphalt roofing after installation.     

 

Brands: Airborne burning embers released from a fire.   

 

Bridging: Method of re-roofing with metric-sized shingles.         

 

Built-Up Roof: Flat or low-sloped roof consisting of multiple layers of asphalt and ply sheets.    

 

Bundle: Package of shingles. There are 3, 4, or 5 bundles per square.    

 

Butt edge: Lower edge of the shingle tabs        

 

Caulk: To fill a joint with mastic or asphalt cement to prevent leaks.        

 

CDX: A grade of plywood commonly used as a sheeting material (See OSB).     

 

Chalk line: A line made on the roof by snapping a taut string or cord dusted with chalk. Used for alignment purposes.    

 

Class "A": Highest fire-resistance rating for roofing per ASTM E-108. Indicates roofing is able to withstand severe exposure to fire originating from sources outside the building.      

 

Class "B": Fire-resistance rating that indicates roofing material is able to withstand moderate exposure to fire originating from  sources outside the building.    

 

Class "C": Fire-resistance rating that indicates roofing material is able to withstand light exposure to fire originating from sources outside the building.    

 

Closed-cut valley: Method of valley treatment in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed 2 inches from the valley centerline. The valley flashing is not exposed.  

 

Coating: Layer of viscous asphalt applied to the base material in which granules or other surfacing is embedded.           

 

Collar: Pre-formed flange placed over a vent pipe to seal the roof around the vent pipe opening. Also called vent sleeve.           

 

Color-through: During manufacturing, the color is mixed throughout the roofing material to become an integral part of it. When the product is cut, the affected area shows the same color as the surface.

 

Concealed-nail method: Application of roll roofing in which all nails are driven into the underlying course of roofing and covered by a cemented overlapping course. Nails are not exposed to the weather.         

Condensation: The change of water from vapor to liquid when warm, moisture-laden air comes in contact with a cold surface.           

 

Counter flashing: That portion of the flashing attached to a vertical surface to prevent water from migrating behind the base flashing.          

 

Course: Row of shingles or roll roofing running the length of the roof.    

 

Coverage: Amount of weather protection provided by the roofing material. Depends on the number of layers of material between the exposed surface of the roofing and the deck, e.g., single coverage, double coverage.         

 

Cricket: Peaked saddle construction at the back of a chimney to prevent accumulation of snow and ice and to deflect water from around the chimney.         

 

Cutout: The open portions of a strip shingle between the tabs.   

 

Dead-Level Asphalt: A roofing asphalt conforming to the requirements of ASTM Specification D 312, Type I. This asphalt is for use in roofs which do not exceed a ¼ in 12 slope (2%).        

 

Deck or Decking: The structural "skin" of a roof over which roofing in applied. Most new homes have decking made of plywood.

 

There are four main types of decking commonly used on residential roofing projects      

 

Plywood - Plywood is strong, durable, and light. It comes in many grades with ratings from A to D. Use only exterior grade plywood for decking. The thickness of plywood depends on the spacing of the rafters.     

OSB - Oriented strand board (OSB) is cheaper than plywood, but not as strong as plywood, and does not hold nails as well as plywood. One side has a slip resistant coating and should be placed facing up.          

Tongue and groove 2-by-6 - If a roof will be seen from the inside (no ceiling installed), tongue and groove is used. It is a wood decking that provides great insulation without additional rigid roof insulation in moderate climates. Also, the boards can be painted or stained on the inside to match the interior.      

Step sheathing - Step sheathing is used alone or in combinations with solid sheathing for installation of tiles or shakes. Step sheathing allows air circulations under the tiles by using 1-by-6 or 2-by-6 boards that are evenly spaced so that air can move under the tiles or shakes.   

 

Dimensional shingle: A shingle that is textured, overlayed, or laminated and designed to produce a three-dimensional effect. Similar to Laminated shingle and Architectural shingle.   

 

Dormer: Framed window unit projecting through the sloping plane of a roof.      

 

Double coverage: Application of asphalt roofing such that the lapped portion is at least two inches wider than the exposed portion, resulting in two layers of roofing material over the deck.

 

Downspout: Pipe for draining water from roof gutters. Also called a Leader.      

 

Drip edge: A non-corrosive, non-staining material used along the eaves and rakes to allow water run-off to drip clear of underlying construction.

 

Dutch lap method: Application of giant individual shingles with the long dimension parallel to the eaves. Shingles are applied to overlap adjacent shingles in each course as well as the course below.

 

Eaves: Horizontal, lower edge of a sloped roof.

 

Eaves flashing: Additional layer of roofing material applied at the eaves to help prevent damage from water back-up.     

 

Edge venting: The installation of a vent material along the roof edge (e.g., Starter Vent) as part of a ventilation system. Edge vent material should be used in conjunction with other venting material (e.g., ridge vent) as it not intended for use by itself.           

 

Edging strips: Boards nailed along eaves and rakes after cutting back existing wood shingles to provide secure edges for re-roofing with asphalt shingles.    

 

Exposed nail method: Application of roll roofing in which all nails are driven into the cemented, overlapping course of roofing. Nails are exposed to the weather.         

 

Exposure: Portion of the shingle exposed to the weather. Exposure is measured from the butt of one shingle to the butt of the next.          

 

Exposure-grade plywood: Type of plywood approved for exterior use by the American Plywood Association.    

 

Fascia: Horizontal trim at the eaves that covers the rafter ends.  

 

Feathering strips: Tapered wood filler strips placed along the butts of old wood shingles to create a level surface when re-roofing over existing wood shingle roofs. Feathering strips are also called horse feathers.          

 

Felt: Fibrous material saturated with asphalt and used as an underlayment of sheathing paper.    

 

Fiber-cement: A roofing material that has cellulose (wood fiber) mixed into it. Cellulose absorbs water and can add greatly to the roof's weight, while reducing its longevity.   

 

Fiberglass mat: Asphalt roofing base material manufactured from glass fibers.  

 

Flashing: Pieces of metal or roll roofing used to prevent seepage of water into a building around any intersection or projection in a roof such as vent pipes, chimneys, adjoining walls, dormers and valleys. Galvanized metal flashing should be minimum 26-gauge. There are 4 main types of flashing used in residential roofing systems          

 

Flashing cement: An asphalt-based cement used to bond roofing materials. Flashing cement is also known as mastic.   

 

Flat Asphalt: A roofing asphalt conforming to the requirements of ASTM Specification D 312, Type II. This asphalt is for use in roofs which do not exceed a ½ in 12 slope (4%).       

 

FM: Factory Mutual Research Corp. is an independent organization that evaluates building materials        

 

Framing member: A hip joist or ridge joist that supports the roof          

 

Free-tab shingles: Shingles that do not contain factory-applied strips or spots of self-sealing adhesive. 

 

Gable: The upper portion of a sidewall that comes to a triangular point at the ridge of a sloping roof.      

 

Gable roof: A type of roof containing sloping planes of the same pitch on each side of the ridge. A gable roof typically contains a gable at each end.   

 

Gambrel roof: A type of roof containing two sloping planes of different pitch on each side of the ridge. The lower plane has a steeper slope than the upper. A gambrel roof usually contains a gable at each end, just like a standard gable roof.       

 

Granules: Ceramic-coated colored crushed rock that is applied to the exposed surface of asphalt roofing products.       

 

Gutter: Trough that channels water from the eaves to the downspouts.   

 

Head lap: Shortest distance from the butt edge of an overlapping shingle to the upper edge of a shingle in the second course below. Triple-coverage portion of the top lap of strip shingles.   

 

HEX shingles: Shingles that have the appearance of a hexagon after installation.           

 

Hip: The inclined external angle formed by the intersection of two sloping roof planes. The hip runs from the ridge to the eaves. 

 

Hip roof: Type of roof containing sloping planes of the same pitch on each of four sides. Contains no gables.   

 

Hip shingles: Shingles used to cover the inclined external angle formed by the intersection of two sloping roof planes.   

 

Ice & Water Shield: Self-adhering waterproofing shingle underlayment designed to protect against water infiltration caused by ice damage or wind-driven rain. 

 

Ice dam: Condition formed at the lower roof edge by the thawing and re freezing of melted snow on the overhang. Can force water up and under shingles, causing leaks.

 

Intake Ventilation: The part of a ventilation system used to draw fresh air in. Usually vents installed in the soffit or along the eaves of a building.      

 

Interlocking shingles: Individual shingles that mechanically fasten to each other to provide wind resistance.       

 

Joists: Any of the small timbers or metal beams ranged parallel from wall to wall in a structure to support a floor or ceiling.           

 

Laminated shingles: Strip shingles containing more than one layer of tabs to create extra thickness. Also called Three-dimensional shingles or Architectural shingles.   

 

Lap: To cover the surface of one shingle or roll with another.     

 

Lap cement: Asphalt-based cement used to adhere overlapping plies of roll roofing.      

 

Lean-to roof: A roof with one slope only that is built against a higher wall.          

 

Life-cycle cost: The total lifetime cost of a roof. Calculated by adding maintenance costs to the installed price, then deducting the added value the roof provides when the home is resold.   

 

Low slope application: Method of installing asphalt shingles on roof slopes between two and four inches per foot.        

 

Mansard roof: A type of roof containing two sloping planes of different pitch on each of four sides. The lower plane has a much steeper pitch than the upper, often approaching vertical. Contains no gables.        

Mastic: An asphalt-based cement used to bond roofing materials. Also known as flashing cement.         

 

Metal drip edge: A narrow strip of non-corrodible metal used at the rake and eave to facilitate water runoff.         

 

Mineral stabilizers: Finely ground limestone, slate, traprock or other inert materials added to asphalt coatings for durability and increased resistance to fire and weathering.

 

Mineral-surfaced roofing: Asphalt shingles and roll roofing that are covered with granules.         

 

Modified Bitumen: Roofing asphalt that has been blended with some of a broad range of materials which improve its performance characteristics.     

 

Nesting: Method of re-roofing with new asphalt shingles over old shingles in which the top edge of the new shingle is butted against the bottom edge of the existing shingle tab.

 

New construction: Installing a roof system on new construction.

 

No-cutout shingles: Shingles consisting of a single, solid tab with no cutouts.   

 

Non-prorated warranty: A warranty which provides full replacement costs for the item(s) covered during the full term of the warranty. In contrast, a prorated warranty merely reimburses a percentage of replacement costs, depending on the age of the roof.    

 

Non-veneer panel: Any wood based panel that does not contain veneer and carries an APA span rating, such as wafer board or oriented strand board.          

 

Normal slope application: Method of installing asphalt shingles on roof slopes between 4 inches and 21 inches per foot.           

 

Open valley: Method of valley construction in which shingles on both sides of the valley are trimmed along a chalk line snapped on each side of the valley. Shingles do not extend across the valley. Valley flashing is exposed.          

 

Organic felt: An asphalt roofing base material manufactured from cellulose fibers.         

 

Organic shingle: Shingle primarily manufactured from wood pulp, cellulose and other natural fibers        

 

Oriented-strand board (OSB): A commonly used, manufactured decking material that shares characteristics of both plywood and waferboard

 

Overhang: That portion of the roof structure that extends beyond the exterior walls of a building.

 

Pallets: Wooden platforms used for storing and shipping bundles of shingles.   

 

Parapet: A low protective wall that extends above the roofline or balcony for support.    

 

Pitch:  Degree of roof incline, expressed as the ratio of the rise to the span, both measured in feet. Also known as "slope."           

 

Plastic cement: A compound used to seal flashings and in some cases to seal down shingles as well as for other small waterproofing jobs. Where plastic cement is required for sealing down shingles, use a dab about the size of a half dollar unless otherwise specified.       

 

Ply: Number of layers of roofing, e.g., one-ply, two-ply.

 

Quick-setting cement: Asphalt-based cement used to adhere tabs of strip shingles to the course below. Also used to adhere roll roofing laps applied by the concealed-nail method.  

 

Racking: Roofing application method in which shingle courses are applied vertically up the roof rather than across and up. Not a recommended procedure.

 

Rafter: Supporting framing member immediately beneath the deck, sloping from the ridge to the wall plate.         

 

Rake: The inclined edge of a sloped roof over a wall from the eave to the ridge. 

 

Random-tab shingles: Shingles on which tabs vary in size and exposure.          

 

Re-cover (overlay): The installation of a new roof system over an existing system without removing an existing system.  

 

Release Tape: A plastic or paper strip that is applied to the back of self-sealing shingles. This strip prevents the shingles from sticking together in the bundles, and need not be removed for application. 

 

Re-roofing: Installing a new roof system on a building that is not new.    

 

Ridge: The uppermost, horizontal external angle formed by the intersection of two sloping roof planes.   

 

Ridge shingles: Shingles used to cover the horizontal external angle formed by the intersection of two sloping roof planes.           

 

Rise: Vertical distance from the eaves line to the ridge.  

 

Roll roofing: Asphalt roofing products manufactured in roll form.          

 

Roofing tape: An asphalt-saturated tape used with asphalt cements for flashing and patching asphalt roofing.    

 

Run: Horizontal distance from the eaves to a point directly under the ridge; one-half the span.    

 

Saturant: Asphalt used to impregnate an organic felt base material.       

 

Saturated felt:  Asphalt-impregnated felt used as an underlayment between the deck and the roofing material.     

 

Scuffing: Marring of shingle; occurs when impact loosens or removes granules  

 

Self-Sealing Shingles: Shingles with factory-applied strips or spots of self-sealing adhesive.    

 

Self-Sealing Strip Or Spot: Factory-applied adhesive that bonds shingle courses together after application when exposed to the heat of the sun.      

 

Selvage: That portion of roll roofing overlapped by the succeeding course to obtain double coverage.   

 

Shading: Slight differences in shingle color that may occur as a result of normal manufacturing operations.        

 

Sheathing: Exterior-grade boards used as roof deck material.   

 

Shed roof: A roof containing only one sloping plane. Has no hips, ridges, valleys or gables.      

 

Single coverage: Asphalt roofing that provides one layer of roofing material over the deck.        

 

Slope:  Degree of roof incline expressed as the ratio of the rise to the run, both measured in feet.          

Smooth-Surfaced Roofing:        Roll roofing that is covered with ground talc or mica instead of granules (coated).         

 

Soffit: Finished underside of the eaves.

 

Soil stack: Vent pipe that penetrates the roof providing air intake for plumbing systems 

 

Span: The horizontal distance from eaves to eaves.       

 

Special Steep Asphalt: A roofing asphalt conforming to the requirements of ASTM Specification D 312, Type IV. This asphalt is for use in roofs which do not exceed a 6 in 12 slope (50%).    

 

Specialty Eaves Flashing Membrane: A self-adhering, waterproofing shingle underlayment designed to protect against water infiltration due to ice dams or wind-driven rain.   

 

Square: Unit of roof measure equal to 100 square feet. 

 

Square-Tab Shingles: Shingles on which tabs are all the same size and exposure.         

 

Standing Seam: A type of metal roofing system           

 

Starter strip: Asphalt roofing applied at the eaves that provides protection by filling in the spaces under the cutouts and joints of the first course of shingles.     

 

Steep Asphalt: A roofing asphalt conforming to the requirements of ASTM Specification D 312, Type III. This asphalt is for use in roofs which do not exceed a 3 in 12 slope (25%).

 

Steep slope application: Method of installing asphalt shingles on roof slopes greater than 21 inches per foot.    

 

Step flashing: Flashing application method used where a vertical surface meets a sloping roof plane.     

 

Strip shingles: Asphalt shingles that are approximately three times as long as they are wide.      

 

Tab: The exposed portion of strip shingles defined by cutouts.  

 

Talc: See Back surfacing.         

 

Tar paper: See "Felt"    

 

Tear off: Removing an existing roof system.     

 

Telegraphing: A shingle distortion that may arise when a new roof is applied over an uneven surface.     

 

Three-dimensional shingles: See laminated shingles.   

 

Three-tab shingle: The most popular type of asphalt shingle usually 12" x 36" in size with three tabs.      

 

Top lap: That portion of the roofing covered by the succeeding course after installation.

 

UL: Underwriters Laboratories, Inc. is an independent organization that evaluates building materials         

 

UL label: Label displayed on packaging to indicate the level of fire and/or wind resistance of asphalt roofing.     

 

Underlayment:  A layer of asphalt saturated (sometimes referred to as tar paper) which is laid down on a bare deck before shingles are installed to provide additional protection for the deck.         

 

Valley:  The internal angle formed by the intersection of two sloping roof planes to provide water runoff. 

 

Vapor barrier: Any material used to prevent the passage of water vapor.           

 

Vent: Any outlet for air that protrudes through the roof deck, such as pipe or stack. Any device installed on the roof, gable or soffit for the purpose of ventilating the underside of the roof deck.        

 

Vent sleeve: See collar.

 

Wafer board: Also Chipboard; a lower grade of wood panel       

 

Woven Valley: Method of valley construction in which shingles from both sides of the valley extend across the valley and are woven together by overlapping alternate courses as they are applied. The valley flashing is not exposed.