The definitions of terms included in this glossary are those pertinent to the roofing trade and are not necessarily those found in standard dictionaries. Some of the terms included are colloquial in nature and are used with the meanings applicable only to the roofing trade.
APP. Atactic Polypropylene or torch-on cap sheet.
Atactic. A polymer featuring a random arrangement of pendent groups on each side of the carbon chain.
Backing. Lumber placed behind or between other members to give support and strength.
Back-Mopping. Mopping the back or underside of roofing material.
Barge Rafter. Same as fascia board. But on the rake or gable end of the roof.
Base Sheet. The first layer of roofing applied on the deck. Also, a dry or slip sheet.
Bitumen. A class of amorphous, black or dark colored, (solid, semi-solid or viscous) cementitious substances, natural or manufactured, composed principally of high molecular weight hydrocarbons, soluable in carbon disulfide, and found in asphalts, tars, pitches and asphaltites. A generic term used to denote any material composed principally of bitumen.
Bleeding. The draining or loosening of saturants from the roofing material.
Blister. A swelling and separating of the top layer of roofing from the underlayment. A bladder like air pocket.
Bond. To fasten or stick together.
Buckles. Bends, crumples, or curls in roofing.
Built-Up Roof. Roof formed by a number of layers of roofing mopped together with hot asphalt abbreviated as BUR.
Cap Sheet. A finish roofing material, used as a covering for a built-up roof.
Cap Nails. A tin flat disk and nail, giving greater holding area to the nail head. Used in windy areas and on soft roofing materials. (A requirement for fiberglass felts).
Cant Strip. A beveled strip used to break the 90 degree angle where the roof meets walls or curbs.
Caulking. To make water tight by plugging with Vulkem caulking.
Condensation. The change from vapor to liquid form, as from steam to water.
Coping. The top covering of a wall; may be metal, tile, masonary, or wood. Also called metal cap or parapet cap.
Combo Base. Glass fiber reinforced base sheet with a laminated Kraft paper backing used on nailable decks to keep asphalt from running through the base sheet to the roof sheeting.
Conductor Head. Collects water from scupper or drain pipe and funnel it into a down pipe (usually on outside of the wall).
Counterflashing. Flashing that extends over another flashing.
Course. A continuous row or layer of shingles or other roofing material.
Cricket. A relatively small elevated area of a roof constructed to divert water out of a dead or flat valley or around other projections.
Curb. A protective rim.
Cured. Completely dry; moisture free.
Dead Load Rafters. Sheeting, roof membrane, shingles, shakes, tile, actual weight of roof and the roof structure.
Debris. Accumulated rubbish, trash, and fragments on roof.
Deck or Substrata. The roof surface to be covered; a small platform used for walking.
Diverter. A piece of metal bent at right angles to change the flow of rain water.
Downspout. A pipe or conductor to carry the water from a roof.
Dry Rot. Wood decay caused by a fungus that consumes the cellulose portion of the wood, leaving a soft skeleton that readily crumbles to a powder. Wood structures that are inadequately ventilated and constantly exposed to moisture are especially vulnerable to dry rot.
Eaves. The projecting lower edge of a roof.
Exposure. The portion of roofing exposed to the weather.
Elasticity. The property of a membrane allowing it to return to its original size and shape after the removal of stress.
Elongation. Lengthening or stretching ability to accommodate movement.
Fascia Board. A board attached to the bottom of rafters acting as a finishing board.
Felt. A roofing material manufactured from cellulose fibers of rags, paper, wood or fiberglass.
Fishmouth. An open seam or a ripple on the roof surface.
Flood Coat. The top layer of an asphalt which the rock is embedded on a rock surfaced built-up roof.
Flush. A term applied to surfaces that are level and form a single, unbroken surface.
Gravel. Crushed stone or rock used for surfacing roofs.
Gutter. A trough installed along the eaves to carry off water.
Hatch. An opening in the roof; an access hole to the attic.
Impregnate. To cause, to be filled or permeated with; to saturate.
Insulation. A material to prevent the passage of heat or sound; also used to reduce fire hazard.
Irish Flax. An imported brownish roll fiber material used for flashing purposes.
Joint. The point at which two or more surfaces are united.
Kettle. A metal vessel for heating asphalt.
Live Load. Moving roof installation equipment, wind, snow, ice or rain (temporary weight on the roof).
Mastic. A thick adhesive mixture of preparations such as asphalt; used for repairing roofs.
Metal Edging. A metal trim used around the outside edges of a roof.
Modified Bitumen. Prefabricated bitumen roofing membranes modified by elastomeric or polymeric compounds.
Modifier. Any compound that is added to a formulation to obtain certain performance enhancements.
Mopping. An installation of bitumen applied with a mop or mechanical device to the substrate or to the felts of a Built-up roof or modified bitumen membrane.
Overflow. A roof drain in wall, above outlet elevation, for excess water or back-up to roof drain.
Overhang. The length of rafter projecting beyond the wall line.
Parapet. A low wall above the roof level.
Pipe Collar. Where pipe flashing meets the pipe.
Pipe Flashing. A preformed sheet metal unit (1 piece flashing) used at a pipe pentration through roof.
Pitch. The slope of a roof, indicated by the relation of the rise 10" high.
Platform. A raised area in which equipment is et-on usually 6" to 10" high to the span.
Ply. A layer of roofing material.
Primer. A thin asphalt base sprayed or brushed on roof or sheet metal before applying asphalt.
Rake. The slope of a roof; the sloping edge on a gable roof that may be covered with a bargeboard.
Recover (Reroof). To apply a new roof over an old roof.
Red Rosion. Red slip sheet used under a base sheet.
Ridge. The point on a double-sloping roof at which the rafters meet the ridge pole.
Ridge Shingles. Units of roofing made for ridge covering.
Rot. Decay that attacks wood. The two major types are dry rot and wet rot.
SBS. Styrene Butadiene Styrene. An SBS modified asphalt combined with a polyester or fiberglass core.
Scupper. A hole or gutter bordering a deck; to let water run through a wall to a conductor head.
Seam. A visible line of junction between two parts; a ridge made in joining two sheets or roofing.
Sheathing (Sheeting). The boards or other material used for covering the frame or roof structure.
Solid-Mopping. A continuous mopping of a surface, with no area left unmopped.
Slip Sheet. A light sheet of paper applied over roof sheathing to prevent the roofing from bonding to sheeting. May be called dry sheet.
Spot-mopping. A mopping pattern in which hot Bitumen is applied in roughly circular areas. A grid of unmopped perpendicular bands is left on the roof.
Square. A unit of measure of roofing area equal to 100 square feet 10' by 10' area = 100 sq. ft.
Storm Collar. A narrow strip of metal formed to fit around vent pipes.
Tappered Fiberboard. Wood pulp that is molded into a sheet and used for feathering bumps or edges of plywood or roof sheeting.
Tear-Off. To remove completely an existing roofing membrane.
Thermal Shock. The stress producing phenomenon resulting from sudden temperature changes in a roof membrane when for example; a rain shower follows brilliant sunshine.
Torch-On / Cap Sheet. Granular cap sheet required to be heat welded in place with a torch.
Turbine / Whirly Vent. A wind driven vent to draw heat from the attic, usually 12" to 14" in diameter. UV. APP, and to a lesser extent, SBS is sensitive to UV (Ultra Violet) light and both will weather best when protected from UV exposure.
Valley. The angle formed by the meeting of two roof slopes.
Valley Metal. Sheet metal used in a valley usually 24" wide.
Web / Yellow Jacket. A woven cloth or organic filaments used in repairs or reinforcement of mastic.
Z-Bar. Metal flashing used especially on walls where roof, plaster, or wood siding meet.
MV Roofing Inc. dba Mission Valley Roofing is a California Corporation - CSLB Lic# 1057584