Roof Repair Terms

Abrasion Resistance

the ability to resist being worn away by contact with another moving, abrasive surface, such as foot traffic, mechanical equipment, wind-blown particles, etc.

Accelerated Weathering

the exposure of a specimen to a specified test environment for a specified time with the intent of producing in a shorter time period, effects similar to actual weathering.

Acid etch

in waterproofing, the use of a strong acid to remove the surface of concrete to expose the aggregate.

Acrylic coating

a liquid coating system based on an acrylic resin. Generally, a latex-based coating system that cures by air drying.

Active metal (anodic)

a metal or material that readily gives up electrons to a cathodic (noble) material. (See anodic). An active metal will corrode in the presence of moisture when in contact with a cathodic metal.

Adhesion

steady or firm attachment.

AFA

American Fiberboard Association

Aged R-value

thermal resistance value established by utilizing artificial conditioning procedures for a prescribed time period.

Aging

the effect on materials that are exposed to an environment for an interval of time.

AIA

American Institute of Architects

Alligatoring

the cracking of the surfacing bitumen on a bituminous roof or coating on a SPF roof, producing a pattern of cracks similar to an alligator's hide; the cracks may not extend completely through the surfacing bitumen or coating.

Aluminum

a nonrusting, malleable metal sometimes used for metal roofing and flashing.

Anodic

a metal or material that readily gives up electrons to a cathodic material in the presence of a electrolyte (see Galvanic series).

Anticapillary hem

a hem used in a metal panel seam to reduce the potential for water migration.

APC

American Plastics Council.

APP

see Atactic Polypropylene.

Apron Flashing

a term used for a flashing located at the juncture of the top of the sloped roof and a vertical wall, chimney or steeper-sloped roof.

Architectural shingle

an asphalt shingle that provides a dimensional appearance.

Area practices

design or application techniques peculiar to a specific geographical region.

ASA

American Subcontractors Association

ASC

Associated Specialty Contractors

ASHRAE

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

Asphalt emulsion

a mixture of asphalt particles and an emulsifying agent, such as bentonite clay and water.

Asphalt primer

see Primer.

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. (see Shingle)

Asphaltene

a high molecular weight hydrocarbon fraction precipitated from asphalt by a designated solvent (paraffinic naphtha) at a specified temperature and solvent-asphalt ratio.

Atactic polypropylene

a group of high molecular weight polymers formed by the polymerization of propylene.

AWPA

American Wood Preservatives Association

Back-nailing (also referred to as "Blind-nailing")

the practice of blind nailing the back portion of a roofing ply, steep roofing unit, or other components in a manner so that the fasteners are covered by the next sequential ply, or course, and are not exposed to the weather in the finished roof system.

Ballast

a material, such as aggregate or precast concrete pavers, which employs its mass and the force of gravity to hold (or assist in holding) single-ply roof membranes in place.

Barrel vault

a building profile featuring a rounded profile to the roof on the short axis, but with no angle change on a cut along the long axis.

Base flashing (membrane base flashing)

plies or strips of roof membrane material used to close-off and/or seal a roof at the horizontal-to-vertical intersections, such as at a roof-to-wall juncture. Membrane base flashing covers the edge of the field membrane. (see Flashing.)

Base sheet

an impregnated, saturated, or coated felt placed as the first ply in some low-slope roof systems.

Batten seam

a metal panel profile attached to and formed around a beveled wood or metal batten.

Bentonite

a porous clay formed by the decomposition of volcanic ash that swells 5 to 6 times its original volume in the presence of water.

Bi-Level Drain

see Dual-Level Drain.

Bird Screen

wire mesh used to prevent birds from entering the building through ventilators, louvers, or other openings. (See Insect Screen.)

Bitumen-Stop

see Envelope and Bleed Sheet.

Blackberry (also referred to as "Blueberry" or "Tar-boil")

a small bubble or blister in the flood coat of an aggregate-surfaced built-up roof membrane.

Bleed-sheet

a sheet material used to prevent the migration of bitumen.

Blind-nailing

the use of nails that are not exposed to the weather in the finished roofing system.

Blocking

sections of wood (which may be preservative treated) built into a roof assembly, usually attached above the deck and below the membrane or flashing, used to stiffen the deck around an opening, act as a stop for insulation, support a curb, or serve as a nailer for attachment of the membrane and/or flashing.

BOCA

Building Officials and Code Administrators, International, Inc. (author of "The BOCA National Building Code").

Bond

the adhesive and/or cohesive forces holding two components in positive contact.

Bond, Mechanical

adhesion between surfaces resulting from interfacial forces or a physical interlocking.

Boot

(1) a covering made of flexible material, which may be preformed to a particular shape, used to exclude dust, dirt, moisture, etc., from around a penetration; (2) a flexible material used to form a closure, sometimes installed at inside and outside corners.

Bridging

(1) when membrane or base flashing is unsupported at a juncture; (2) bridging in steep-slope roofing occurs when reroofing over standard-sized asphalt shingles with metric-sized asphalt shingles.

Broadcast

uniformly cast or distribute grandular or aggregate surfacing material.

Buckle

an upward, elongated displacement of a roof membrane frequently occurring over insulation or deck joints. A buckle may be an indication of movement within the roof assembly.

Built-up roof (BUR)

a continuous, semi-flexible roof membrane, consisting of multiple plies of saturated felts, coated felts, fabrics or mats assembled in place with alternate layers of bitumen, and surfaced with mineral aggregate, bituminous materials, a liquid-applied coating or a granule-surfaced cap sheet.

Bundle

an individual package of shakes or shingles.

Butt joint

a joint formed by adjacent, separate sections of material, such as where two neighboring pieces of insulation abut.

Butyl

rubber-like material produced by polymerizing isobutylene.

Butyl rubber

a synthetic elastomer based on isobutylene and a minor amount of isoprene. It can be vulcanizable and features low permeability to gases and water vapor.

C-channel

a structural framing member.

Calender

(1) to press between rollers or plates in order to smooth and glaze or to thin into sheets; (2) a machine for calendering.

Camber

a slight convexity, arching or curvature (as of a beam, roof deck or road).

Cant

in SPF-based roofing, a beveling of foam at horizontal/vertical joints to increase strength and promote water run off.

Cap flashing

(1) usually composed of metal, used to cover or shield the upper edges of the membrane base flashing wall flashing; (2) a flashing used to cover the top of various buildings components, such as parapets or columns. (see Flashing and Coping.)

Capacitance meter

a device used to locate moisture or wet materials within a roof system by measuring the ratio of the change to the potential difference between two conducting elements separated by a non-conductor.

Catalyst

an ingredient that initiates a chemical reaction or increases the raate of a chemical reaction when combined with another chemical.

Caulk

a composition of vehicle and pigment used at ambient temperatures for filling/sealing joints or junctures, that remains elastic for an extended period of time after application.

Cavitation

the formation of a partial vacuum or cavity in a liquid.

CCF

100 cubic feet.

Cementitious waterproofing

heavy cement-based compounds and various additives that are mixed and packaged for use in a dry form; the packaged mixture is then mixed with water and liquid bonding agents to a workable concrete-like consistency.

Centistoke

a unit of viscosity; the ratio of a liquid's absolute viscosity to the density of that liquid.

Chalk

a powdery residue on the surface of a material.

Chalking

the formation of a powdery surface condition from the disintegration of a binder or elastomer.

Chemical resistance

the ability to withstand contact with specified chemicals without a significant change in properties.

Chimney

stone, masonry, prefabricated metal, or a wood framed structure, containing one or more flues, projecting through and above the roof.

Chlorosulfonated polyethylene (CSPE or CSM)

probably best known by the DuPont trade name HypalonTM), a synthetic, rubber-like thermoset material, based on high molecular weight polyethylene with suphonyl chloride, usually formulated to produce a self-vulcanizing membrane. Classified by ASTM Standard D 5019.

Cleat

a continuous metal strip, or angled piece, used to secure metal components (also see Clip).

Clip

a non-continuous metal component or angle piece used to secure two or more metal components together. (see Cleat.)

Closed-cut valley

a method of valley application in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed back approximately 2 inches (51 mm) from the valley centerline.

Coal tar

a dark brown to black colored, semi-solid hydrocarbon produced by the distillation of coal. Coal tar pitch is further refined to conform to the following roofing grade specifications:

Coal tar felt

a felt that has been saturated or impregnated with refined coal tar.

Coal tar roof cement

a trowelable mixture of processed coal tar base, solvents, mineral fillers and/or fibers. Classified by ASTM Standard D 4022, "Coal Tar Roof Cement, Asbestos Container."

Coarse orange peel surface texture

a surface showing a texture where nodules and valleys are approximately the same size and shape. This surface is acceptable for receiving a protective coating because of the roundness of the nodules and valleys.

Coated fabric

fabrics that have been impregnated and/or coated with a plastic like material in the form of a solution, dispersion hot-melt or powder. The term also applies to materials resulting from the application of a preformed film to a fabric by means of calendering.

Coating

a layer of liquid material applied to a surface for protection or appearance.

Code

a collection of laws (regulations, ordinances or statutory requirements) adopted by governmental authority. (see Building code and Model code.)

Cohesion

the molecular forces of attraction by which the body of a material is held together.

Cold Flow

relatively slow deformation of a material at or below room temperature. (See Creep).

Cold Process Built-Up Roof

a continuous, semi-flexible roof membrane, consisting of a ply or plies of felts, mats or other reinforcement fabrics that are laminated together with alternate layers of liquid-applied (usually asphalt-solvent based) roof cements or adhesives installed at ambient or a slightly elevated temperature.

Cold roof assembly

a roof assembly configured with the insulation below the deck, not typically in contact with the deck, allowing for a ventilation space. The temperature of the roof assembly remains close to the outside air temperature.

Color stability

the ability of a material to retain its original color after exposure to weather.

Combing ridge

a term used to describe an installation of finishing slate or wood at the ridge of a roof whereby the slates on one side project beyond to the apex of the ridge.

Combustion

a chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light either as glow or flames; the process of burning.

Composite board roof insulation

rigid board insulation generally comprised of perlite or wood fiberboard factory bonded to polyisocyanurate or polystyrene.

Compounded thermoplastics

a category of roofing membranes made by blending thermoplastic resins with plasticizers, various modifiers, stabilizers, flame retardants, UV absorbers, fungicides, and other proprietary substances, alloyed with proprietary organic polymers.

Concealed plate

see Cover plate.

Condensate

the liquid resulting from the condensation of a gas.

Condense

to make denser or more compact, as when a material (e.g., water vapor) changes from its gas phase to its liquid phase.

Conductance, Thermal

the thermal transmission in unit time through unit area of a particular body or assembly having defined surfaces, when unit average temperature difference is established between the surfaces. C=Btu/h.ft2.F (C=W/m2.K).

Construction joint

(1) a joint where two successive placements of concrete meet; (2) a separation provided in a building which allows its component parts to move with respect to each other.

Contamination

the process of making a material or surface unclean or unsuited for its intended purpose, usually by the addition or attachment of undesirable foreign substances.

Coping

the covering piece on top of a wall exposed to the weather, usually made of metal, masonry, or stone and sloped to carry off water.

Copolymerization

a chemical reaction that results in the bonding of two or more dissimilar monomers to produce large, long-chain molecules that are copolymers.

Core cut or core sample

(1) a sample from a low-slope roof system taken for the purpose of obtaining primarily qualitative information about its construction. Typically, core cut analysis can verify or reveal the type of membrane surfacing; the type of membrane; the approximate number of plies; the type, thickness and condition of the insulation (if any); and the type of deck used as a substrate for the roof system. (2) for in SPF-based roof systems, core cuts are used to obtain both quantitative and qualitative information, such as the thickness of the foam, the thickness and adhesion of the coating, thickness of individual passes and adhesion between passes and the adhesion of the foam to its substrate.

Counter batten

vertical wood strips installed on sloped roofs over which horizontal battens are secured. The primary roof covering is attached or secured to these horizontal battens.

Course

(1) the term used for a row of roofing material that forms the roofing, waterproofing or flashing system; (2) one layer of a series of materials applied to a surface (e.g., a five-course wall flashing is composed of three applications of roof cement with one ply of felt or fabric sandwiched between two layers of roof cement).

Cover board

an insulation board used over closed cell plastic foam insulation (e.g., polyisocyanurate) to prevent blistering when used in conjunction with hot bituminous membranes. Suitable cover board insulation are glass-faced siliconized gypsum board, glass-fiber board, perlite board, wood-fiber board of mineral-fiber board. Cover boards are also recommended between polyisocyanurate insulation and single ply membranes to protect the polyisocyanurate.

Coverage

the surface area uniformly covered by a specific quantity of a particular material at a specific thickness.

CPE

Chlorinated Polyethylene.

Cream time

time in seconds (at a given temperature) when the A and B components of polyurethane foam will begin to expand after being mixed. Recognizable as a change in color of the materials.

Cricket

a relatively small area of a roof constructed to divert water from a horizontal intersection of the roof with a chimney, wall, expansion joint or other projection. (see Saddle.)

Cross-linking

the formation of chemical bonds between polymeric chains. Cross-linking of rubber is referred to as vulcanizing or "curing."

Crystalline waterproofing

a compound of cement, quartz or silica sand, and other active chemicals that are mixed and packaged for use in a dry powder form; the packaged mixture is then mixed with water and applied to a concrete surface where it penetrates into the pores of concrete.

CSM

ASTM designation for chlorosulfonated polyethylene. (See CSPE.)

Cupola

a relatively small roofed structure, generally set on the ridge or peak of a main roof area for ventilation or aesthetic purposes.

Cure

a process whereby a material is caused to form permanent molecular linkages by exposure to chemicals, heat, pressure, and/or weathering.

Cured concrete

concrete that has attained its intended design performance properties.

Curing compound

a liquid that is sprayed or otherwise applied to newly placed concrete which retards the loss of water during curing.

Cutoff

a permanent detail designed to prevent lateral water movement in an insulation system and used to isolate sections of a roofing system. (Note: A cutoff is different from a tie-in, which may be a temporary or permanent seal.) (see Tie-In.)

Dampproofing

treatment of a surface or structure to resist the passage of water in the absence of hydrostatic pressure.

Dead loads

the weight of a structure itself, including the weight of fixtures or equipment permanently attached to it.

Deck

a structural component of the roof of a building. The deck must be capable of safely supporting the design dead and live loads, including the weight of the roof systems, and the additional live loads required by the governing building codes and provide the substrate to which the roofing or waterproofing system is applied the structural surface of a building to which a roof assembly is installed. Decks are either non-combustible (e.g., corrugated metal, concrete, or gypsum) or combustible (e.g., wood plank or plywood).

Degradation

a deleterious change in the chemical structure, physical properties or appearance of a material from natural or artifical exposure (e.g., exposure to radiation, moisture, heat, freezing, wind, ozone, oxygen, etc.)

Delamination

separation of the laminated layers of a component or system.

Dew-point temperature

the temperature at which air becomes saturated with water vapor. The temperature at which air has a relative humidity of 100%.

Diffusion

the movement of water vapor from regions of high concentration (high water vapor pressure) toward regions of lower concentration.

Dimensional stability

the degree to which a material maintains its original dimensions when subjected to changes in temperature and humidity.

Dome

a roof that is shaped like a half-circle, or a variation of one.

Double coverage

application of asphalt, slate, or wood roofing such that the lapped portion is at least 2 inches (50 mm) wider than the exposed portion, resulting in two layers of roofing material over the deck.

Double lock standing seam

in a metal roof panel or metal cap, a standing seam that uses a double overlapping interlock between two metal panels. (see Standing seam.)

Downspout

a vertical pipe or conduit used to carry runoff water from a scupper, conductor head or gutter of a building to a lower roof level or to the ground or storm water runoff system.

Drain

an outlet or other device used to collect and direct the flow of runoff water from a roof area.

Dry

free or relatively free from a liquid, especially water; (2) to remove water or moisture.

Dry film thickness

the thickness, expressed in mils, of an applied and cured coating or mastic. For comparison, see Wet film thickness.

Drying time

the time required for the loss of volatile components so that the material will no longer be adversely affected by weather conditions such as dew, rain, or freezing.

Durability

the ability to withstand physical, chemical, or environmental abuse.

Dynamic load

any load which is nonstatic, such as a wind load or a moving live load.

Eave height

the vertical dimension from finished grade to the eave.

ECH

polyepichlorohydrin, commonly referred to as epichlorohydrin. (see Epichlorohydrin.)

Edge venting

the practice of providing regularly spaced or continuously protected (e.g., louvered) openings along a roof edge or perimeter, used as part of a ventilation system to dissipate heat and moisture vapor.

EIP

ethylene interpolymer.

Elastomer

a macromolecular material that returns rapidly to its approximate initial dimensions and shape after substantial deformation by a weak stress and subsequent release of that stress.

Elastomeric coating

a coating that is capable of being stretched at least twice its original length (100 percent elongation) and recovering to its original dimensions.

Elongation

the ratio of the extension of a material to the length of the material prior to stretching.

Embrittlement

the loss of flexibility or elasticity of a material.

End lap

the distance of overlap where one ply, pane, or piece extends beyond the end of the immediately adjacent underlying ply, panel, or piece.

EPDM

Ethylene propylene diene monomer (see also Ethylene propylene diene terpolymer.)

Epoxy

a class of synthetic, thermosetting resins that produce tough, hard, chemical-resistant coatings and adhesives.

Equiviscous temperature (EVT)

the temperature at which a bitumen attains the proper viscosity for built-up membrane application.

Equiviscous temperature (EVT) for asphalt

the recommended EVT for roofing asphalt (ASTM D 312, Type I, II, III, or IV) is as follows Mop Application: the temperature at which the asphalt's apparent viscosity is 125 centipoise (0.125 Pa s). Mechanical Spreader Application: the temperature at which the asphalt's apparent viscosity is 75 centipoise (0.075 Pa s). Note: In order to avoid the use of two kettles if there are simultaneous mop and mechanical spreader applications, the EVT for mechanical spreader application can be used for both application techniques.

Ethylene interpolymers (EIP)

a group of thermoplastic compounds generally based on PVC polymers from which certain single-ply roofing membranes can be formulated.

EVT

Equiviscous temperature.

Exotherm

heat generated by a chemical reaction.

Expansion joint

a structural separation between two building elements that allows free movement between the elements without damage to the roofing or waterproofing system.

Exposure

(1) the traverse dimension of a roofing element or component not overlapped by an adjacent element or component in a roof covering. For example, the exposure of any ply in a built-up roof membrane may be computed by dividing the felt width, minus 2 inches (51 mm), by the number of shingled plies; thus, the exposure of 36 inch (914 mm) wide felt in a shingled, four-ply membrane should be approximately 81/2 inches (216 mm); (2) the dimension of sidewall or roofing covering that is not covered or overlapped by the up slope course of component. The typical exposure for a standard-size, 3-tab shingle is 5 inches (127 mm), depending upon manufacturer specifications.

Eyebrow

a dormer, usually of small size, whose roof line over the upright face is typically an arched curve, turning into a reverse curve to meet the horizontal at either end. Also, a small shed roof projecting from the gable end of the larger, main roof area.

Factory Mutual Research (FMR)

commonly referred to as "FM," a research and testing organization that classifies roofing components and assemblies for their fire, traffic, impact (hail), weathering, and wind-uplift resistance for four major insurance companies in the United States.

Fading

any lightening of initial color.

Fascia

(1) in steep-slope roofing, a board that is nailed to the ends of a roof rafter; sometimes supports a gutter; (2) in a low-slope roofing, the vertical or steeply sloped roof or trim located at the perimeter of a building. Typically, it is a border for the low-slope roof system.

Feathering strips

tapered wood filler strips placed along the butt ends of old wood shingles to create a relatively smooth surface when reroofing over existing wood shingle roofs. Referred to in some regions of the country as "horse feathers" or leveling strips.

Felt machine (Felt Layer)

a mechanical device used for applying bitumen and roofing felt or ply sheet simultaneously.

Fiberglass Insulation

blanket or rigid board insulation, composed of glass fibers bound together with a binder, faced or unfaced, used to insulate roofs and walls. Rigid boards usually have an asphalt and kraft paper facer.

Field seam

a splice or seam made in the field (not factory) where overlapping sheets are joined together using an adhesive, splicing tape, or heat- or solvent-welding.

Fillet

a heavy bead of waterproofing compound or sealant material generally installed at the point where vertical and horizontal surfaces meet; the desired effect to take out the 90 degree angle at the base of a vertical flashing.

Film thickness

the thickness of a membrane or coating. Wet film thickness is the thickness of a coating as applied; dry film thickness is the thickness after curing. Film thickness is usually expressed in mils (thousandths of an inch).

Fine mineral-surfacing

water-insoluble, inorganic material, more than 50 percent of which passes through a No. 35 sieve. Used on the surface of various roofing materials and membranes to prevent sticking.

Fire retardant treated (FRT) plywood

plywood which has been impregnated, under pressure, with mineral salts; in the event of fire, the burning wood and salts emit noncombustible gases and water vapor instead of the usual flammable vapors.

Flaking

in protective coatings, the detachment of small pieces of the coating film.

Flame spread

a propagation of a flame away from its source of ignition.

Flange

the projecting edge of a rigid or semi-rigid component, such as a metal edge flashing flange.

Flashing

components used to weatherproof or seal the roof system edges at perimeters, penetrations, walls, expansion joints, valley, drains, and other places where the roof covering is interrupted or terminated. For example, membrane base flashing covers the edge of the field membrane, and cap flashings or counterflashings shield the upper edges of the base flashing.

Flashing collar

(sometimes referred to as a roof jack or flashing boot) an accessory flashing used to cover and/or seal soil pipe vents and other penetrations through the roof.

Fleece

mats or felts composed of fibers, sometimes used as a membrane backer.

Flood test

the procedure where a controlled amount of water is temporarily retained over a horizontal surface to determine the effectiveness of the waterproofing system.

Fly-in

method of application for roll materials by which the dry sheet is set into the bitumen or adhesive applied to the roof surface.

Foam stop

the roof edge treatment upon which SPF is terminated.

FPL

Forest Products Laboratory.

Froth pack

a term used to describe small, disposable aerosol cans that contain SPF components. Two component froth packs are available to do small repairs for sprayed polyurethane foam-based roofs.

Gable

the vertical triangular portion of the end of a building having a double-sloping roof, from the level of the eaves to the ridge of the roof.

Gable-Shaped Roof

a single-ridge roof that terminates at gable end(s). (See Figure 11.)

Galvanic action

an electrochemical action that generates electrical current between two metals of dissimilar electrode potential.

Galvanize

to coat steel or iorn with zinc.

Gambrel

a roof that has two pitches on each side, where the upper roof area has less slope than the lower roof areas.

Geocomposite

a prefabricated water drainage material used to relieve hydrostatic pressure against waterproofing and promote drainage.

Geotextile

a tightly woven fabric used to restrict the flow of fine soil particles and other contaminants while allowing water to pass freely through; used to protect drainage systems from clogging.

Glass felt

glass fibers bonded into a sheet with resin and suitable for impregnation with asphalt in the manufacture of bituminous waterproofing, roofing membranes and shingles.

Glass mat

a thin mat of glass fibers with or without a binder.

Gloss

the shine, sheen, or luster of a dried film.

Granule

(also referred to as mineral or ceramic granule) opaque, natural, or synthetically colored aggregate commonly used to surface cap sheets, shingles, and other granule-surfaced roof coverings.

Gravel stop

a flanged device, frequently metallic, designed to prevent loose aggregate from washing off the roof and to provide a continuous finished edge for the roofing.

Grout

a mixture of cement, sand, and water used to fill cracks and cavities in masonry.

Gusset

used at the bottom of a steep-slope roof system valley, a large flat metal piece(s) wider than the valley to help prevent build-up at the base of the valley, either from debris or ice dam formations.

Gypsum board panels

cementititious board stock with noncombustible core primarily comprised of gypsum that is commonly used as a barrier board thermal barrier or cover board in a roof assembly.

Hardness

the relative resistance of a material to indentation.

Heat Aging

controlled exposure of materials to elevated temperatures over time.

Heat seaming

the process of joining thermoplastic films, membranes, or sheets by heating and then applying pressure to bring both materials in contact with each other. (see Heat welding.)

Heat welding

method of melting and fusing together the overlapping edges of separate sheets or sections of polymer modified bitumen, thermoplastics or some uncured thermoset roofing membranes by the application of heat (in the form of hot air or open flame) and pressure. (see Heat seaming.)

Hip

the inclined external angle formed by the intersection of two sloping roof planes.

Hoist

a mechanical lifting device.

Honeycomb

voids left in concrete resulting from failure of the mortar to effectively fill the spaces among course aggregate particles.

Hue

the subjective perception of color such as red, yellow, green, blue, purple or some combination; white, black or gray possess no hue.

HVAC

heating, ventilating, and air conditioning equipment.

Hydration

the chemical reaction by which a substance (such as Portland cement) combines with water, giving off heat to form a crystalline structure in its setting and hardening.

Hydrostatic pressure

the pressure equivalent to that exerted on a surface by a column of water of a given height.

Hygroscopic

attracting, absorbing and retaining atmosphere moisture.

Mansard

a decorative steep-sloped roof on the perimeter of a building.

Masonry

construction, usually set in mortar, of natural building stone or manufactured units, such as brick, concrete block, adobe, glass block, tile, manufactured stone or gypsum block.

Mat

a thin layer of woven, non-woven, or knitted fiber that serves as reinforcement to the material or membrane.

Material safety data sheets (MSDS)

a written description of the chemicals in a product and other pertinent data including such things as safe handling and emergency procedures. In accordance with OSHA regulations, it is the manufacturer's responsibility to produce an MSDS and the employer's responsibility to communicate its contents to employees.

MBMA

Metal Building Manufacturers Association

Mechanical damage

in SPF-based roofing, physical damage to a completed SPF-based roof system not caused by normal wear and tear.

Membrane

a flexible or semi-flexible roof covering or waterproofing whose primary function is to exclude water.

Metal Film

a layer of foil made from a single metallic substance, or from an alloy, that is laminated to a membrane during manufacture. The metal foil serves as the weathering surface of the membrane or flashing material.

Metal rain collar

a metal counterflashing used to wrap a penetration and prevent water infiltration though the top of the penetration base flashing.

Metal roof shingle

an interlocking metal sheet having an installed weather exposure less than 3 square feet (279000 mm2 or 0.28 m2) per sheet.

Meter

unit of length measurement in the metric system, 1 meter is equal to 39.37 inches.

Microbiological Resistance

the ability of a material to resist attack and degradation by various air- and soil-borne micro-organisms.

Mil

a unit of measure, one mil is equal to 0.001 inches, or 25.4 micrometers (um), often used to indicate the thickness of a roofing membrane.

Millimeter

a unit of measure equal to one thousandth (0.001) of a meter, or 0.03937 inches.

Mineral fiber

insulation composed principally of fibers manufactured from rock, slag or glass, with or without binders.

Mineral stabilizer

a fine, water-insoluble inorganic material, used in a mixture with solid or semi-solid bituminous materials.

Mineral-surfaced sheet

a roofing sheet that is coated on one or both sides with asphalt and surfaced with mineral granules.

Miter joint

a joint between two members at an angle to each other; each member is cut at an angle equal to half the angle of the junction; usually the members are at right angles to each other.

Model Codes

a compilation of standards or codes established to provide uniformity in regulations pertaining to building construction. Examples ICBO - International Conference of Building Officials; BOCA - Building Officials and Code Administrators; SBC - Standard Building Code.

Moisture contour map

a map used to graphically define the location of moisture within a roof assembly after a moisture scan has been performed.

Moisture scan

the use of a mechanical device (capacitance, infrared, or nuclear) to detect the presence of moisture within a roof assembly. (see Non-destructive testing.)

Monolithic

formed from or composed of a single material; seamless.

Mop-and-flop

an application procedure in which roofing elements (insulation boards, felt plies, cap sheets, etc.) are initially placed upside down adjacent to their ultimate locations; coated with adhesive or bitumen; and turned over and adhered to the substrate.

Mud cracking

surface cracking resembling a dried mud flat.

Multiple Coat

two or more layers of coating applied to a substrate.

Nailer

(sometimes referred to as blocking) a piece or pieces of dimensional lumber and/or plywood secured to the structural deck or walls, which provide a receiving medium for the fasteners used to attach membrane or flashing.

NBP

acrylonitrile butadiene polymer blend. One proprietary NBP membrane is commonly referred to as nitrile butadiene copolymer.

Negative side waterproofing

an application wherein the waterproofing system and source of hydrostatic pressure are on opposite sides of the structural element.

Nesting

(1) the installation of new metal roof deck directly on top of existing metal roof deck; (2) a method of reroofing with new asphalt shingles over existing shingles in which the top edge of the new shingle is butted against the bottom edge of the existing shingle.

Newton (N)

SI unit of measure for force.

Night seal (or night tie-in)

a material and/or method used to temporarily seal a membrane edge during construction to protect the roofing assembly in place from water penetration. Usually removed when roofing application is resumed.

NIST

National Institute of Standards and Technology

Nitrile rubber

a membrane whose predominant resinous ingredient is a synthetic rubber made by the polymerization of acrylonitrile with butadiene.

Noble

in reference to metal, inert; opposite of active.

Non-Breathing Membrane

a membrane that does not allow significant amounts of water vapor or air to pass through; which has a perm rating 1.0 or less per ASTM E 96, Procedure E.

Non-Vulcanized Membrane

a membrane manufactured from thermoplastic compounds that retains its thermoplastic properties throughout the service life of the membrane.

Nonflammable

not easily ignited and not burning rapidly if ignited.

Nonoxidizing

a material which resists oxidation in exterior exposures or accelerated weathering.

Nonwoven

a term used to describe the random arrangement of reinforcing fibers (glass, polyester, etc.) in a mat or scrim.

NRCA

National Roofing Contractors Association.

Nuclear hydrogen detection (NHD) meter

a device that contains a radioactive source to emit high velocity neutrons into a roof system. Reflecting neutrons are measured by a gauge that is used to detect hydrogen; the quantity of hydrogen detected may be linked to the pressure of water.

Nylon

generic name for a family of polyamide polymers, used as a scrim in some fabric-reinforced sheeting.

Pan

the bottom flat part of a roofing panel which is between the ribs of the panel.

Parapet wall

the part of a perimeter wall that extends above the roof.

Partially attached

a roofing assembly in which the membrane has been "spot affixed" to a substrate, usually with an adhesive or a mechanical device.

Pascal

SI unit of measure for force per unit area.

Pass line

the junction of two passes of SPF. A distinct line is formed by the top skin of the bottom pass and the next pass adhering to this skin.

Peel strength

the average load per unit width required to separate progressively a flexible member from a rigid member or another flexible member.

Percent Elongation

in tensile testing, the increase in the gauge length of a specimen measured at or after fracture of the specimen within the gauge length. Usually expressed as a percentage of the original gauge length.

Perm

see Permeance.

Permeance

(1) the rate of water vapor transmission per unit area at a steady state through a material, membrane, or assembly; (2) the time rate of water vapor transmission through unit area of flat material or construction induced by unit vapor pressure difference between two specific surfaces, under specified temperature and humidity conditions. The English (inch.pound) unit of measurement for permeance is gr/h.ft2.in. Hg, which is commonly referred to as "perm" units.

Phased application

the installation of a roofing or waterproofing system during two or more separate time intervals or different days. Application of surfacings at different time intervals are typically not considered phased application. (see Surfacing.) A roofing system not installed in a continuous operation.

Pigment

an insoluble compounding material used to impart color.

Pinhole

a tiny hole in a coating, film, foil, membrane, or laminate comparable in size to one made by a pin.

Pitch

see Coal tar.

Pittsburgh lock seam

a method of interlocking metal, usually at a slope change.

Plastic Film

a flexible sheet made by the extrusion of thermoplastic resins.

Plasticizer migration

in some thermoplastic roofing membranes, the loss of plasticizer chemicals from the membrane, resulting in shrinkage and embrittlement of the membrane, typically PVC.

Pliability

the material property of being flexible or moldable.

PMR

protected membrane roof.

Polyester

a polymer in which the repeated structural unit in the chain is of the ester type.

Polyisobutylene (PIB)

a product formed by the polymerization of isobutylene. May be compounded for use as a roof membrane material.

Polymer modified bitumen

see Modified bitumen.

Polymerization

a chemical reaction in which monomers are linked together to form polymers.

Polypropylene

a polymer prepared by the polymerization of propylene as the sole monomers.

Polyvinyl chloride (PVC)

a synthetic thermoplastic polymer prepared from vinylchloride. PVC can be compounded into flexible and rigid forms through the use of plasticizers, stabilizers, fillers, and other modifiers. Rigid forms are used in pipes; flexible forms are used in the manufacture of sheeting and roof membrane materials.

Ponding

the excessive accumulation of water at low-lying areas on a roof that remains after the 48 hours after the end rainfall under conditions conducive to drying.

Popcorn surface texture

in SPF roofing, the condition in which the foam surface shows a coarse texture where valleys form sharp angles. This surface is unacceptable for proper coating and protection.

Positive side waterproofing

an application where the waterproofing systems and the source of the hydrostatic pressure are on the same side of the structural element.

Pourable sealer

a type of sealant often supplied in two parts and used at difficult-to-flash penetrations, typically in conjunction with pitch-pockets to form a seal.

Press brake

a machine used in cold-forming sheet metal or strips of metal into desired profiles.

Primer

(1) a thin, liquid-applied solvent-based bitumen that may be applied to a surface to improve the adhesion of subsequent applications of bitumen; (2) a material which is sometimes used in the process of seaming single-ply membranes to prepare the surfaces and increase the strength (in shear and peel) of the field splice; (3) a thin liquid-applied material that may be applied to the surface of SPVF to improve the adhesion of subsequent application of SPVF protective coatings.

Protected membrane roof (PMR)

an insulated and ballasted roofing assembly in which the insulation and ballast are applied on top of the membrane (sometimes referred to as an "inverted roof assembly").

Protection mat

a sacrificial material used to shield one roof system component from another.

Psychrometric chart

chart showing the relationship between dew point temperature, dry bulb temperature, wet bulb temperature and relative humidity.

Purlin

horizontal secondary structural member that transfers loads from the primary structural framing.

R-value

see Thermal resistance.

Rafter

one of a series of sloped structural members, that extend from the ridge or hip to the downslope perimeter or eave, designed to support the roof deck and its associated loads.

Rake

the sloped edge of a roof at or adjacent to the first or last rafter.

RCI

Roof Consultants Institute

RDCA

Roof Deck Contractors Association

Reflectivity

see Light reflectance.

Reinforced membrane

a roofing or waterproofing membrane that has been strengthened by the addition or incorporation of one or more reinforcing materials, including woven or nonwoven glass fibers, polyester mats or scrims, nylon, or polyethylene sheeting.

Release tape (or strip)

a plastic film or paper strip that is applied to the back of self-sealing shingles and other materials. The strip prevents the material from sticking together in the roll or bundle. With asphalt shingles, the strip need not be removed for application of the shingles.

Reroofing

the process of re-covering, or tearing-off and replacing an existing roof system.

Resistance, Thermal

the average temperature difference between two defined surfaces of a particular body or assembly when unit thermal transmission in unit time through unit area is established between the surfaces. R=_Fòhòsòft2/Btu (R=Kòm2/W).

Ridge cap

a material or covering applied over the ridge of a roof.

Ridge vent

a ventilator located at the ridge that allows the escape of warm and/or moist air from the attic area or rafter cavity.

RIEI

Roofing Industry Educational Institute

Roll Goods

a general term applied to rolls of roofing felt, ply sheet, etc., which are typically furnished in rolls.

Roll roofing

coated felts, either smooth or mineral-surfaced.

Roof area divider

refer to area divider.

Roof assembly

an assembly of interacting roof components including the roof deck, vapor retarder (if present), insulation, and roof covering.

Roof covering

the exterior roof cover or skin of the roof assembly, consisting of membrane, panels, sheets, shingles, tiles, etc.

Roof Diaphragm

a structural roof deck that is capable of resisting shear that is produced by lateral forces, such as wind or seismic loads.

Roof or Roofer's Cement

see Asphalt Roof Cement or Coal Tar Roof Cement.

Roof seamer

(1) machine that crimps neighboring metal roof panels together; (2) machine that welds laps of membrane sheets together using heat, solvent, or dielectric energy.

Roof system

a system of interacting roof components, generally consisting of membrane or primary roof covering and roof insulation (not including the roof deck) designed to weatherproof and, sometimes, to improve the building's thermal resistance.

Rosin paper (specifically Rosin-sized sheathing paper)

a nonasphaltic paper used as a sheathing paper or slip sheet in some roof systems.

Run

horizontal dimension of a slope.

Saddle

a small tapered/sloped roof area structure that helps to channel surface water to drains. Frequently located in valley. A saddle is often constructed like a small hip roof or pyramid with a diamond-shaped base. (see Cricket.)

Saturated felt

a felt that has been immersed in hot bitumen; the felt adsorbs as much bitumen as it can retain under the processing conditions, but remains porous and contains voids.

SBCCI

Southern Building Code Congress International, Inc.

Scarfed

shaped by grinding.

Screen wall

a nonstructural wall erected around units or curbs on a roof. Typically the framing consists of girts with a wood or metal covering attached to the frame.

Scupper

drainage device in the form of an outlet through a wall, parapet wall or raised roof edge lined with a soldered sheet metal sleeve.

SDI

Steel Deck Institute.

Sealant

(1) a material that has the adhesive and cohesive properties to form a seal; (2) a mixture of polymers, fillers, and pigments used to fill and seal joints where moderate movements is expected; unlike caulking, it cures to a resilient solid.

Sealer

a coating designed to prevent excessive absorption of finish coats into porous surfaces; a coating designed to prevent bleeding.

Seam

a joint formed by mating two separate sections of material. Seams can be made or sealed in a variety of ways, including adhesive bonding, hot-air welding, solvent welding, using adhesive tape, sealant, etc.

Seam Strength

the force or stress required to separate or rupture a seam in the membrane material.

Self-drilling screw

a fastener that taps and drills its own hole during application.

Self-tapping screw

a fastener that forms receiving threads when turned in a previously drilled hole.

Selvage

(1) an edge or edging that differs from the main part of a fabric, granule-surfaced roll roofing or cap sheet, or other material; (2) a specially defined edge of the material (lined for demarcation), which is designed for some special purpose, such as overlapping or seaming.

Separator layer

refer to Slip sheet.

Set

to convert into a fixed or hardened state by chemical or physical action.

Shark fin

an upward-curled felt side lap or end lap.

Shed roof

a roof having only one sloping plane and no hips, ridges or valleys.

Shingle

(1) a small unit of prepared roofing designed for installation with similar units in overlapping rows or courses on inclines normally exceeding 3:12 slope (14 degrees); (2) to cover with shingles; (3) to apply any sheet material in succeeding overlapping rows like shingles.

Shore "A" Hardness

a measure of firmness of a material by means of a Durometer Hardness Gauge. (A measure of 20 is about the firmness of a gum eraser; 90 is about that of a rubber heel.)

Shrinkage crack

in waterproofing, a separation in a material, such as a concrete substrate, caused by the inability of the material to resist a reduction in size which occurs during its hardening or curing process or both.

Side lap

the continuous longitudinal overlap of neighboring like materials.

Side Lap-Ganging

pattern or application for roofing materials, as related to the amount of cover or side overlap of adjacent like materials.

Sieve

an apparatus with square apertures for separating sizes of material.

Sill

the bottom horizontal framing member of an opening, such as below a window or door.

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 (either homogeneous or composite) rather than multiple layers.

T-joint

the condition created by the overlapping intersection of three or four sheets in the membrane.

Tack-free time

in SPF-based roofing, a curing phase of polyurethane foam to when the material is no longer sticky. When the polyurethane foam is tack free, it can be sprayed over with another pass, referred to as a "lift". With some care the polyurethane foam can be walked on soon after it is tack free.

Tapered edge strip

a tapered insulation strip used to (1) elevate and slope the roof at the perimeter and at curbs, and (2) provide a gradual transition from one layer of insulation to another.

Tar

a brown or black bituminous material, liquid or semi-solid in consistency, in which the predominating constituents are bitumens obtained as condensates in the processing of coal, petroleum, oil-shale, wood, or other organic materials.

Tarred felt

see Coal tar felt.

Tear strength

the maximum force required to tear a specimen.

Tensile Fatigue Resistance

the ability of a given membrane material to resist "fatigue" and/or other damage (such as loss of elasticity) caused by the alternate stretching and relaxing of the material over a period of time.

Tensile Test

a test in which a specimen is subjected to increasing longitudinal pulling stress until fracture occurs.

Termination

the treatment or method of anchoring and/or sealing the free edges of the membrane in a roofing 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 (palms) bound together to shed water.

Thermal Barrier

a material applied over polyurethane 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 minutes.

Thermal bridge

the penetration of a material of high thermal conductivity (e.g., a metal insulation or roof membrane fastener) through a material of low thermal conductivity (e.g., thermal insulation); the result is a lowered thermal resistance for the assembly.

Thermal conductivity (k)

the time rate of heat flow through a unit area of a homogeneous material in a direction perpendicular to isothermal planes induced by a unit temperature gradient is called thermal conductivity (k or k-value). In English (inch-pound) units of measurement, it is the number of BTUs that pass through a 1 inch (25 mm) thickness of a 1 square foot (0.09 m2) sample of material in one hour with a temperature difference between the two surfaces of 1 degree F. In English (inch-pound) units it is expressed as Btu.inch/h.ft2.degree F. Note 1: A thermal conductivity (k) value applies to 1 inch (25 mm) thickness of a specific material. Note 2: It is mathematically incorrect to add, multiply, or divide the thermal conductivity (k) value of a material to determine the thermal performance value of a different thickness of the same material. If it is necessary to determine the thermal performance of a specific thickness of a material, it is appropriate to convert the thermal conductivity (k) of the material to a thermal resistance (R) value (i.e., R = 1/k), and then perform the mathematical calculation.

Thermal expansion

the increase in the dimension or volume of a body due to temperature variations.

Thermal insulation

a material applied to reduce the flow of heat.

Thermal resistance (R)

under steady conditions, thermal resistance is the mean temperature difference between two defined surfaces of material or construction that induces unit heat flow through a unit area. In English (inch.pound) units it is expressed as degree F.ft2.h/Btu. Note 1: A thermal resistance (R) value applies to a specific thickness of a material or construction. Note 2: The thermal resistance (R) of a material is the reciprocal of the thermal conductance (C) of the same material (i.e., R = 1/C). Note 3: Thermal resistance (R) values can be added, subtracted, multiplied, and divided by mathematically appropriate methods.

Thermal stress

stress introduced by uniform or non-uniform temperature change in a structure or material that is contained against expansion or contraction.

Thermogram

a visible light record of the display of an infrared camera system via a Polaroid print, 35mm film, video tape, or computer generated image.

Thermoplastic

a material that softens when heated and hardens when cooled. This process can be repeated provided that the material is not heated above the point at which decomposition occurs.

Thermoset

a class of polymers that, when cured using heat, chemical, or other means, changes into a substantially infusible and insoluble material.

Thixotropic

the property of a material that enables it to stiffen in a relatively short time on standing, but6 upon agitation or manipulation to change to a very soft consistency or to a fluid of high viscosity, the process being completely reversible.

Through-wall flashing

a water-resistant membrane or material assembly extending totally through a wall and its cavities, positioned to direct water within the wall to the exterior, usually through weep holes.

Tie-Off

(in roofing and waterproofing) the transitional seal used to terminate a roofing or waterproofing application at the top or bottom of flashings, or by forming a watertight seal with the substrate, membrane or adjacent roofing or waterproofing system.

Toggle bolt

a bolt having a nut with pivoted, flanged wings that close against a spring when it is pushed through a hole, and open after emerging from the hole; used to fasten objects to a hollow wall or to a wall which is accessible only from one side.

Torch-applied

method used in the installation of polymer modified bitumen membranes characterized by using open flame propane torch equipment.

TPO

thermoplastic olefin.

Transverse seam

the joint between the top of one metal roof panel and the bottom of the next panel, which runs perpendicular to the roof slope.

Tuckpointing

the process of removing deteriorated mortar from an existing masonry joint and troweling new mortar or other filler into the joint.

Warm roof assembly

a roof assembly configured with each component placed immediately on top of the preceding component; each component is in contact with the adjacent component. No space is provided for ventilation of the roof assembly. Also known as a "compact" roof assembly.

Water Absorption

the amount of water absorbed by a material after immersion for a prescribed period of time. May be expressed as a percentage of the original weight of the material.

Water cutoff

see Cutoff.

Water table

the level within the ground, below which the soil is saturated with water.

Water-shedding

the ability of individual, overlapping components to resist the passage of water without hydrostatic pressure.

Waterproofing

treatment of a surface or structure to prevent the passage of water under hydrostatic pressure.

Wearing surface

see Wear course.

Weatherometer

an instrument used to subject material specimens to accelerated weathering conditions.

Weep holes

small openings whose purpose is to permit drainage of water that accumulates inside a building component (e.g., a brick wall, skylight frame, etc.).

Wet

a condition where free water is present in a substance.

Wet film thickness

the thickness, expressed in mils, of a coating or mastic as applied but not cured. For comparison, see Dry film thickness.

Wind clip

a steep-slope roofing attachment device that fits over the butt end of tile, slate and stone to help secure individual roofing units from wind uplift.

Wind uplift

the 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.

Wire Tie System

a scheme of attachment for steep-slope roofing units (e.g., tile, slate, and stone) utilizing fasteners (nails and/or screws) in conjunction with wire to make up a concealed fastening system.

Work slab

see Mud slab.

Wythe

a masonry wall, one masonry unit, a minimum of two inches thick.