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Common Roofing Terms and Definitions

Published: 06/11/2020

As the premier family-owned roofing company in the Sarasota and Bradenton area since 2002, AKVM Roofing values transparency in our practices. That includes ensuring our customers understand exactly what we mean when we speak our roofing language so that you can confidently make informed decisions regarding the roofing services performed on your home or business. This comprehensive glossary of roofing terms is a great tool to help you learn more about the inner workings of your home’s front line of defense against wind, rain, algae and pests.

parts of a roof

A

Absorption

The measure of a material’s ability to accept or soak up moisture

Accelerated Weathering

The process in which materials are tested by intentional exposure in a controlled environment to various elements such as heat, water, condensation or light.

Aggregate

A composition of rock, stone, crushed stone, crushed slag, water-worn gravel and/or marble chips used for surfacing a roof system

Algae Discoloration (Fungus Growth)

A type of roof discoloration caused by the growth of algae on its surface

Alligatoring

Patterned cracking of the surfacing bitumen on a built-up roof resembling an alligator’s hide

Aluminum

A lightweight non-rusting metal used in the construction of some roofing components

Ambient Temperature

The temperature of the air

American Method

Method of applying very large individual roofing shingles in which the long dimension is parallel to the rake and shingles are applied with a 3/4-inch space between adjacent shingles in a course

Apron Flashing

A flashing located at the point where the top of the sloped roof and a vertical wall or steeper-sloped roof join

Architectural Shingle

Roofing shingle that provides a dimensional appearance

Asphalt

A bituminous waterproofing agent applied to roofing materials during manufacturing

Asphalt Roofing Cement (Flashing Cement, Mastic)

An asphalt-based cement used to bond roofing materials

B

Back-Nailing (Blind-Nailing)

The practice of nailing the back portion of a roofing ply so that the fasteners are concealed by the next sequential ply or course and are not exposed to the weather in the finished roof system

Back Surfacing

Fine mineral matter applied to the back side of shingles to keep them from sticking

Balanced System

A ventilation system in which half of the required ventilation is provided by vents located in the upper portion of the roof with the other half provided by soffit vents

Ballast

An anchoring material, such as aggregate or concrete pavers, that uses gravity to hold single-ply roofing membranes in place

Barrel Vault (Tunnel Vault, Wagon Vault)

An arched or rounded roof profile

Base Flashing

Flashing attached with the purpose of directing the flow of water onto the roof covering

Base Ply

The lowermost ply of a roof system

Base Sheet

An impregnated, saturated or coated felt placed as the first ply in some multi-ply built-up and modified bitumen roof membranes

Batten

A metal or wood strip or cap that covers the joints between adjacent roofing panels or tiles.

Batten Seam

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

Bitumen

A type of liquid binding agent that holds asphalt together

Blackberry (Blueberry, Tar-Boil)

A small bubble or blister in the flood coating of roofing membrane

Blisters

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

Blocking

Sections of wood built into a roof assembly, typically used to reinforce the deck around an opening, act as a stop for insulation, support a curb or to serve as a nailer for attachment of the roofing membrane and/or flashing

Bridging (Butting Up)

A method of reroofing in which the new shingles follow the contour of the old roofing.

Built-Up Roof

A flat or low-slope roof consisting of multiple layers of asphalt and ply sheets

Built-Up Roof Membrane (BUR)

A semi-flexible multi-ply roofing membrane, consisting of layers of felts or fabrics between which alternate layers of bitumen are applied

Bundle

A single package of shingles. There are 3, 4 or 5 bundles per square.

Butt Edge

The lower edge of the shingle tabs

Butt Joint

A joint formed by adjacent sections of material, such as shingles or insulation

Button Punch

A practice of indenting two or more thicknesses of metal that are pressed against each other, forming a ‘button’ or dimple that secures the two pieces together

Butyl

Rubber-like material produced in sheets or blended with other elastomeric materials to make sealants, coatings and adhesives

C

Camber

A slight convex curve of a surface that serves to allow water to run off of the roof

Canopy

Any overhanging or projecting roof structure, typically over entrances or doors

Cant

A beveling of foam at a right-angle joint for strength and water runoff

Cant Strip

A beveled or triangular-shaped strip of wood or other material that serves as a transitional plane between the horizontal surface of a roof and the vertical surface of the outer wall of the structure

Cap Flashing

Flashing, typically metal, used to cover the upper edges of the membrane base flashing

Cap Sheet

A coated sheet used to cover and protect the layers of roofing below it for the purpose of helping to extend the life of the roof

Capillary Action

The movement of water through porous materials through water’s cohesive and adhesive properties. Capillary action causes water to be sucked into any small gap in a building; the action is lessened when the gap is larger than a half-inch.

Caulk

To fill a joint or crack with mastic or asphalt cement to help prevent leaks

Cavity Wall

A wall built or arranged to provide an air space within the wall (with or without insulating material), in which the inner and outer materials are joined together by structural framing

CCF

100 cubic feet

Chalking

The degradation or migration of an ingredient in paints, coatings or other materials

Cladding

The material that makes up the exterior layer of a building

Class "A"

The highest fire-resistance rating for roofing; indicates roofing is able to withstand severe exposure to fire originating from sources outside the building

Class "B"

Fire-resistance rating that indicates roofing materials are able to withstand moderate exposure to fire originating from sources outside the building

Class "C"

Fire-resistance rating that indicates roofing materials are able to withstand light exposure to fire originating from sources outside the building

Cleat

A metal strip, plate or metal angle piece used to secure two or more elements together

Closed-Cut Valley

A method of applying roofing materials in which shingles from one side of the valley extend across the valley, while shingles from the other side are trimmed two inches from the valley centerline. This method ensures that the valley flashing is not exposed.

Closure Strip

A metal or foam strip used to seal openings between joined metal panels and flashings

Coal Tar Pitch

A coal tar used as the waterproofing agent in level or low-slope built-up roof membranes

Cold Process Built-Up Roof

A semi-flexible roof membrane consisting of a ply or plies of felts, mats or other reinforcement fabrics that are laminated together with layers of liquid-applied adhesive installed at ambient or slightly elevated temperatures

Collar (Vent Sleeve)

Pre-formed flange placed over a vent pipe to seal the roof around the vent pipe opening

Composition Shingle

A unit of asphalt shingle roofing

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 so that nails are not exposed to the weather

Conductor Head

A transition component between a through-wall scupper and downspout to collect and direct run-off water

Coping

An exposed piece of metal or stone covering the top of a wall; typically sloped to allow water to roll back onto the roof

Cornice

The decorative horizontal molding or projected roof overhang

Counter Flashing

A portion of flashing attached to a vertical surface to help prevent water from getting behind the base flashing

Course

A row of shingles or roll roofing running the length of the roof

Coverage

Amount of weather protection provided by the roofing material, i.e. a single-ply roof provides single coverage, a 2-ply roof provides double coverage, etc.

Cricket

A peaked saddle construction at the back of a chimney to deflect water and help prevent snow and ice from accumulating around the chimney

Cupola

A relatively small roofed structure, generally set on the ridge or peak of a main roof area

Curb

A raised member used to support roof penetrations such as skylights above the level of the roof surface

Cure

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

Cutoff

A permanent detail designed to seal and prevent lateral water movement in an insulation system and used to isolate sections of a roofing system

Cutout

The open portions of a strip shingle between the tabs

D

Damper

An adjustable plate for controlling draft

Dead Level (Zero-Slope)

A surface, such as a rooftop with no intentional slope, that is effectively horizontal or flat

Dead Loads

Permanent non-moving loads that result from the weight of a building’s structural and architectural components, mechanical and electrical equipment, and the roof assembly itself Essentially the same as “dead weight” or “dead weight loads”

Deck (Sheathing)

The surface to which the roofing is applied; typically plywood or oriented strand board (OSB)

Deflection (Bowing, Sagging)

The downward displacement of a roofing system under heavy loads of snow, ice or water

Delamination

Separation of the laminated layers of a component or system

Design Loads

Those loads specified in building codes or standards published by federal, state, county, or city agencies, or in owners’ specifications to be used in the design of a building

Dome

A rounded roof that is shaped like a half-circle

Dormer

A 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

Double Graveling

The process of applying two layers or flood coats of bitumen and aggregate to a built-up roof

Double Lock Standing Seam

A standing seam that utilizes an overlapping interlock between two seam panels

Downspout (Leader)

A pipe for draining water from roof gutters

Drip Edge

A weather-resistant material used along the eaves and rakes to allow water runoff to drip clear of the underlying structure

Dutch Lap Method

Application of very large 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

E

Eaves

The horizontal, lowest edge of a sloped roof that extends beyond the exterior wall

Eaves Flashing

Additional layer of roofing material applied at the eaves to help prevent damage from water backup

Edging Strips

Boards nailed along eaves and rakes after cutting back existing wood shingles to provide secure edges for reroofing with asphalt shingles

Efflorescence

The formulation of crystalline deposits, generally whitish in color, on the surface of stone, brick, concrete, or other masonry surface when moisture moves through and evaporates on the masonry May also be caused by free alkalis leached from mortar, grout or adjacent concrete

Elastomeric Coating

A coating system which, when fully cured, is capable of being stretched at least twice its original length (100% elongation) and recovering to its original dimensions

Ell

An extension of a building at right angles to its length

Expansion Joint

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

Exposed Nail Method

Application of roll roofing in which all nails are driven into the topmost course of roofing; nails are exposed to the weather

Exposure I Grade Plywood

Type of plywood approved by the American Plywood Association for exterior use

Extrusion

A process by which some single-ply roofing membranes are manufactured, which consists of forcing batched and formulated material (which may be molten) through a die. The shape and dimensions of the die determine the shape and dimensions of the finished product.

F

Factory Seam

A splice/seam made by the manufacturer during the assembly of sections of materials into large sheets

Fascia

A flat board, band or face located at a cornice's outer edge

Fasteners

Any of a wide variety of mechanical securement devices and assemblies, including nails, screws, cleats, clips, and bolts, which may be used to secure various components of a roof assembly

Feathering Strips (Horse Feathers)

Tapered wood filler strips placed along the butts of old wood shingles to create a level surface when reroofing over existing wood shingle roofs

Felt

Fibrous material saturated with asphalt and used as an underlayment or sheathing paper

Ferrule

A small metal sleeve placed inside a gutter at the top; a spike is nailed through the gutter into the fascia board to hold the gutter in place while the ferrule acts as a spacer to help retain the gutter’s original shape.

Fiberglass Mat

An asphalt roofing base material manufactured from glass fibers

Field of the Roof

The central or main portion of a roof, excluding the perimeter and flashing

Fire Rating

System for classifying the fire resistances of various materials. Roofing materials are rated Class A, B or C, with Class A materials having the highest resistance to fire originating outside the structure.

Fishmouth (Edge Wrinkle)

A half-cylindrical-shaped opening in a lapped edge or seam, usually caused by wrinkling or shifting of ply sheets during installation; also refers to the half-conical opening formed at a cut edge of shingles.

Flaking

Detachment of a uniform layer of a coating or surface material, usually related to internal movement, lack of adhesion, or passage of moisture

Flange

The projecting edge of a rigid or semi-rigid component. Ex. metal edge flashing flange, skylight flange, flashing boot, structural member, etc.

Flash Point

The lowest temperature of a liquid at which it gives off vapors sufficient to form an ignitable mixture with air near its surface

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

Flat Lock

A method of interlocking metal panels in which one panel edge is folded back on top of itself and the other panel is folded under, hooking the two panels together

Flood Test

The procedure where a controlled amount of water is temporarily retained over a horizontal surface to determine the effectiveness of the waterproofing Free-tab Shingles Shingles that do not contain factory-applied strips or spots of self-sealing adhesive

G

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 a sloping plane on each side of a single ridge with a gable at each end

Galvalume®

Trade name for a protective metal roof coating made from aluminum zinc to prevent corrosion

Galvanize

To coat with zinc

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; this type of roof features a gable at each end.

Granules

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

Gravel Stop

A low profile upward-projecting metal edge flashing with a flange along the roof side, usually formed from sheet or extruded metal. Gravel stops are typically installed along the perimeter of a roof to provide a continuous finished edge for roofing material, which acts as a bitumen-stop during mop application of hot bitumen.

Gutter

The trough that channels rainwater from the eaves to the downspouts

H

Head Lap

Shortest distance from the butt edge of an overlapping shingle to the upper edge of a shingle in the second course below; typically, this portion provides triple coverage of the top lap of strip shingles.

Hem

The edge created by folding metal back on itself

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 Runs from the ridge to the eaves

Hip Roof

A type of roof containing sloping planes of the same pitch on each of four sides. This type of roof contains no gables.

Hip Shingles

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

I

Ice Dam

Ice formed at the lower roof edge by the thawing and refreezing of melted snow on the overhang; can force water up and under shingles, causing damage and potential leaks

Impact Resistance

The ability of a roofing assembly to resist damage from falling objects

Interlocking Shingles

Individual shingles that mechanically fasten to each other to provide wind resistance

L

Laminated Shingles (Architectural Shingles, Dimensional Shingles)

Strip shingles containing more than one layer of tabs to create extra thickness

Lap

To cover the surface of one shingle or roll with another

Lap Cement

An asphalt-based cement used to adhere overlapping plies of roll roofing

Low-Slope Application

Method of installing asphalt shingles on roof slopes between 2:12 and 4:12 (18.5° TO 9.5°)

Louver

A slanted opening for ventilation

M

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, often approaching vertical, pitch than the upper. This type of roof includes no gables.

Masonry Primer

An asphalt-based primer used to prepare masonry surfaces for bonding with other asphalt products

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

N

Natural Ventilation

A ventilation system in which openings in the attic are utilized to circulate natural air flow, drawing hot or moist air out to replace it with fresh outside air

Nesting

A method of reroofing 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

Net Free Vent Area (NFVA)

Area unobstructed by screens, louvers or other materials

No-Cutout Shingles

Shingles consisting of a single, solid tab with no cutouts

Non-Veneer Panel

Any wood-based panel that does not contain veneer and carries an APA span rating, e.g. OSB or wafer board

Normal-Slope Application

Method of installing asphalt shingles on roof slopes between 4:12 and 21:12

O

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, and valley flashing is exposed

Organic Felt

An asphalt roofing base material manufactured from cellulose fibers

Overhang

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

P

Pallets

Wooden platforms used for storing and shipping bundles of shingles

Penetrations

Anything, such as a vent, pipe, stack or chimney, that penetrates a roof deck

Pitch

The degree of roof incline expressed as the ratio of the rise, in inches, to the span, in feet

Ply

The number of layers of roofing materials

Q

Quick-Setting Cement

An 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.

R

Racking

Roofing application method in which shingle courses are applied vertically up the roof rather than across and up; not an industry-recommended method.

Rafter

The 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

Release Tape

A plastic or paper strip that is applied to the back of self-sealing shingles which prevents the shingles from sticking together in the bundles and is not removed prior to application

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

The vertical distance from the eaves line to the ridge

Roll Roofing

Asphalt roofing products manufactured in roll form

Roofing Cement

A compound used to seal flashings, seal down shingles and for other small waterproofing jobs

Roofing Tape

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

Run

The horizontal distance from the eaves to a point directly under the ridge; one-half the span

S

Saturant

Asphalt used to impregnate an organic felt base material Saturated Felt An asphalt-impregnated felt used as an underlayment between the deck and the roofing material

Self-Sealing Cement

A thermal-sealing tab cement built into the shingle to firmly cement the shingles together automatically after they have been applied properly and exposed to warm sun temperatures

Self-Sealing Shingles

Shingles containing factory-applied strips or spots of self-sealing adhesive

Self-Sealing Strip or Spot

Factory-applied adhesive that bonds shingle courses together when exposed to the heat of the sun after application

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 a 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

The degree of roof incline expressed as the ratio of the rise, in inches, to the run, in feet

Smooth-Surfaced Roofing

Roll roofing that is coated with ground talc or mica instead of granules

Soffit

The finished underside of the eaves

Soil stack

A vent pipe that penetrates the roof

Span

The horizontal distance from eave to eave

Specialty Eaves Flashing Membrane

A self-adhesive waterproofing shingle underlayment designed to protect against water infiltration due to ice dams or wind-driven rain

Square

A unit of roof measure covering 100 square feet

Square-Tab Shingles

Shingles on which tabs are all the same size and exposure

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-Slope Application (Mansard)

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 (Three-Tab Shingles)

A single-layer shingle commonly known as a three-tab shingle because it has three tabs

T

Tab

The exposed portion of strip shingles defined by cutouts

Telegraphing

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

Top Lap

That portion of the roofing covered by the succeeding course after installation

Truss

Custom-engineered components that supplement rafters in many newer homes and buildings

U

UL

Underwriters Laboratories, LLC

UL Label

Label displayed on packaging to indicate the listing for fire and/or wind resistance of asphalt roofing

Undereave

Underside area of the overhang at the eave of the roof

Underlayment (Tar Paper)

A layer of asphalt-saturated felt which is laid down on a bare deck before shingles are installed to provide additional protection for the deck

V

Valley

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

Vapor Retarder

Any material used to prevent the passage of water vapor

Vent

Any outlet for air that protrudes through the roof deck, such as a pipe or stack

Ventilators

Devices that eject stale air and circulate fresh air

W

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.

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