Understanding Your Roof

Heritage Roofing, Inc. feels strongly in the importance of making an educated decision when it comes to repairing or replacing your roof. Below are common roofing terms, phrases and definitions associated with residential and commercial roofing, Please contact us if you have any questions, comments or concerns.

The Parts of a Residential Roof

Anatomy of a roof
Here’s a breakdown of of the parts that go into a residential roof, some are not seen once the job is complete. Underneath the shingles, the roof starts with rafters and decking boards, then flashing and a moisture barrier of felt underlayment. Then come the shingles, surrounding the roof itself are the soffit and fascia board. More information available here: http://www.angieslist.com/roofing/roof-anatomy.htm

:: A :: B :: C :: D :: E :: F :: G :: H :: I :: J :: K :: L :: M :: N :: O :: P :: Q :: R :: S :: T :: U :: V :: W :: X :: Y :: Z ::


Algae discoloration
A type of roof discoloration caused by algae. Commonly called fungus growth.

American Method
Application of very large individual shingles with long dimension parallel to the rake. Shingles are applied with a 3/4-inch space between adjacent

shingles in a course.

Angled Fasteners
Roofing nails and staples driven into decks at angles not parallel to the deck.

Apron Flashing
Metal flashing used at chimney fronts.

Asphalt Roofing Manufacturers Association. Organization of roofing manufacturers.

American Society for Testing and Materials. A voluntary organization concerned with development of consensus standards, testing procedures and specifications.

A bituminous waterproofing agent used in various types of roofing materials.

Asphalt Concrete Primer
Asphalt based primer used to prepare concrete and metal for asphalt sealant.

Asphalt Plastic Cement
Asphalt based sealant material, meeting ASTM D4586 Type I or II. Used to seal and adhere roofing materials. Also called mastic, blackjack, roof

tar, bull.

The American Society for Testing and Materials. Organization that sets standards for a wide variety of materials, including roofing.


Back Surfacing
Granular material added to shingle’s back to assist in keeping separate during delivery and storage.

Balanced System
A ventilation system where 50% of the required ventilating area is provided by vents located in the upper portion of the roof with the balance provided

by under eave or soffit vents.

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

Bubbles or pimples in roofing materials. Usually moisture related. In shingles blisters are caused by either moisture under the material or moisture trapped

inside the material.

When shingles are subjected to high winds, and are forced off a roof deck.

Airborne burning embers released from a fire.

A method of reroofing with metric sized shingles.

When a wrinkle or ripple affects shingles or their underlayments.

Built-up Roof
A flat or low-slope roof consisting of multiple layers of asphalt and ply sheets.

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

Butt Edge
The lower edge of the shingle tabs.


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

See asphalt roofing cement.

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

Class “A”
The highest fire-resistance rating for roofing as per ASTM E108. 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.

Closed cut valley
A 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 two

inches from the valley centerline. The valley flashing is not exposed.

A layer of viscous asphalt applied to the base material into which granules or other surfacing is embedded.

GAF’s respected brand name for ventilation products.

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

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.

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

Counter Flashing
The metal or siding material that is installed over roof-top base flashing systems.

Country Mansion®
GAF’s limited lifetime warranty shingle.

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

Amount of weather protection provided by the roofing material. Depends on number of layers of material between the exposed surface of the roofing and the deck

(single coverage, double coverage, etc.).

A peaked water diverter installed behind chimneys and other large roof projections. Effectively diverts water around projections.

When shingles are improperly installed over an existing roof or are over-exposed, they may form a curl or cup. May also be due to a manufacturing defect.

The open portions of a strip shingle between the tabs.


An adjustable plate for controlling draft.

Deck Armor™
Deck Armor™ – premium breathable roof deck protection. It provides a critical extra layer of protection between your shingles and your roof deck — to help

prevent wind-driven rain (or water from other sources) from infiltrating under your shingles and causing damage to your roof structure or to the inside of your home.

The substrate over which roofing is applied. Usually plywood, wood boards, or planks.

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.

A pipe for draining water from roof gutters. Also called a leader.

Drip Edge
A noncorrosive, non-staining material used along the eaves and rakes to allow water runoff to drip clear of underlying construction.

Dubl-Coverage Mineral Guard®
Roll roofing material with 19″ selvage edge for double coverage over roof deck.

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.


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

End Laps
When installing rolled products in roofing, the area where a roll ends on a roof, and is overlapped by the next section of rolled material.

Engineered Wood Association. Tests and sets standards for all varieties of plywood used in the U.S.

The area on any roofing material that is left exposed to the elements.

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.

An extension of a building at right angles to its length.

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


Nails or staples used to secure roofing to the deck.

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

called horsefeathers.

A sheet of asphalt-saturated material (often called tar paper) used as a secondary layer of protection for the roof deck.

The Federal Housing Authority sets construction standards throughout the U.S.

Fiberglass Mat
Fibers condensed into strong, resilient mats for use in roofing materials.

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.

Metal pan extending up or down a roof slope around flashing pieces. Usually at chimneys and plumbing vents

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

Flashing Cement
Sealant designed for use around flashing areas, typically thicker than plastic cement.

Factory Mutual Research Corp.

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


Gable Roof
Traditional roof style; two peaked roof planes meeting at a ridge line of equal size.

GAF cant strips for deflecting water away from flashing areas. Typically used on low slope roofs.

Golden Pledge®
GAF’s strongest limited warranty for shingles. America’s strongest steep slope warranty.

Grand Sequoia®
GAF shingle with wood shake appearance.

Grand Slate™
GAF shingle with slate appearance.

Crushed rock that is coated with a ceramic coating and fired, used as top surface on shingles.

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

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. Features a

gable at each end.

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

The trough that channels water from the eaves to the downspouts.


The method to assure sealing of shingles on very steep slopes, in high wind areas, and when installing in cold weather.

Head lap
Shortest distance from the butt edge of an overlapping shingle to the upper edge of a shingle in the second course below. The triple coverage portion of the top

lap of strip shingles.

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

High Nailing
When shingles are nailed or fastened above the manufacturer’s specified nail location.

The inclined external angle formed by the intersection of two sloping roof planes. Runs from the ridge to the eaves.

Hip Legs
The down-slope ridges on hip roofs.

Hip Roof
A 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.

See feathering strips.


Ice Dam
Condition 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 leaks

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


“L” Flashing
Continuous metal flashing consisting of several feet of metal. Used at horizontal walls, bent to resemble an “L”.

Laminated Shingles
Strip shingles containing more than one layer of tabs to create extra thickness. Also called dimensional or architectural shingles.

The area where roll roofing or rolled underlayments overlap one another during application (see also side laps and end laps).

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

Self-adhering low-slope roofing. Liberty™ systems are applied without torches, open flames, hot asphalt, or messy solvent-based adhesives.

Slatted devises installed ina gable or soffit to ventilate the space below a roof deck and qualize air temperature and moisture.

Low Slopes
Roof pitches less than 4:12 are considered low sloped roofs. Special installation practices must be used on roofs sloped 2:12-4:12. Shingles can not be

installed at slopes less than 2/12.

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. Includes no gables.

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

See asphalt plastic roofing cement.

The general term for the base material of shingles and certain rolled products.

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


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

Modified Bitumen
Rolled roofing membrane with polymer modified asphalt and either polyester or fiberglass reinforcement.

Mixture of sand, mortar, limestone and water used in bonding a chimney’s bricks together.


Nail Guide Line
Painted line on laminated shingles, to aid in the proper placement of fasteners.

When a nail is not fully driven, it sits up off the roof deck.

Natural Ventilation
A ventilation system utilizing ventilators installed in openings in the attic and properly positioned to take advantage of natural air flow to draw

hot summer or moist winter air out and replace it with fresh outside air.

Installing a second layer of shingles aligning courses with the original roof to avoid shingle cupping.

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, 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.

The National Roofing Contractors Association. Respected national organization of roofing contractors.


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 Mat
Material made from recycled wood pulp and paper.

Organic Shingles
Shingles made from organic (paper) mats.

Oriented Strand Board. A decking made from wood chips and lamination glues.

The term used for fasteners driven through roofing material with too much force, breaking the material.

Installing shingle courses higher than their intended exposure.

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


Wooden platforms used for storing and shipping bundles of shingles.

Vents, pipes, stacks, chimneys, anything that penetrates a roof deck.

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

The number of layers of roofing (e.g. one-ply, two-ply).


Quarter Sized
Term for the size of hand sealant dabs, size of a U.S. 25¢ piece.

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.


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

The supporting framing member immediately beneath the deck, sloping from the ridge to the wall plate.

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

Rake Edge
The vertical edge of gable style roof planes.

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

Release Film
The plastic sheet installed on the back of WeatherWatch® and StormGuard® underlayments. Used for packaging and handling. Remove before installation.

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.

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.

Rigid Vent
Hard plastic ridge vent material.

The vertical distance from the eaves line to the ridge.

Roof Louvers
Rooftop rectangular shaped roof vents. Also called box vents, mushroom vents, airhawks, soldier vents.

Roof Plane
A roofing area defined by having four separate edges. One side of a gable, hip or mansard roof.

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. Where cement is required for sealing down shingles, use a

dab about the size of a quarter unless otherwise specified.

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

The horizontal distance from the eaves to a point directly under the ridge. One half the span.


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.

The exposed section of double thickness on Timberline® Series shingles – also called dragon teeth. Shaped to imitate wood shake look on the roof.

Sealant installed on shingles. After installation, heat and sun will activate sealant to seal the shingles to each other.

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. In warm seasons, the seal will be complete in a matter of days. In colder seasons, sealing time depends on the temperature and amount of direct sunlight hitting

the shingles. Hand sealing with cement should be done to ensure sealing in winter.

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.

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

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

Exterior-grade boards used as a roof deck material fastened to rafters to cover a house or building.

The non exposed area on rolled roofing. Area without granules. Designed for nail placement and sealant.

Shed Roof
Roof design of a single roof plane. Area does not tie into any other roofs.

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

GAF’s shingle underlayment. Breather type with fiberglass backing to reduce wrinkles and buckles.

Side Laps
The area on rolled material where one roll overlaps the rolled material beneath it. Also called selvage edge on rolled roofing.

Side Walls
Where a vertical roof plane meets a vertical wall. The sides of dormers etc.

Measured by rise in inches for each 1 inches of horizontal run. A roof in a 1-in-12 slope rises 4 inches for every foot of horizontal distance.

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

The finished underside of the eaves.

Soffit Ventilation
Intake ventilation installed under the eaves, or at the roof edge.

Soil Stack
A vent pipe that penetrates the roof.

The horizontal distance from eaves to eaves.

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

The most common measurement for roof area. one square is 100 square feet (10 by 10 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 Roofing
Generally all slopes higher than 4/12 are considered steep slopes.

Steep-slope Application (Mansard)
Method of installing asphalt shingles on roof slopes greater than 21 inches per foot.

Step Flashing
Metal flashing pieces installed at sidewalls and chimneys for weatherproofing.

GAF waterproof underlayment. Film-surfaced rolled underlayment, 1.5 squares coverage per roll.

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


The bottom portion of traditional shingle separated by the shingle cut-outs.

See back surfacing.

Removal of existing roofing materials down to the roof deck.

When shingles reflect the uneven surface beneath them. Ex: Shingles installed over buckled shingles may show some buckles.

Three-dimensional Shingles
See laminated shingles.

Three-tab Shingle
A single-layer shingle having three tabs.

Timberline® Series
GAF’s trademark name for laminated wood-shake-style shingles.

GAF enhanced Hip and Ridge Shingles.

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

When a roof plane ties into another roof plane that has a different pitch or slope.

Engineered components that supplement rafters in many homes and buildings. Trusses are designed for specific applications and cannot be cut or altered.

The exposed portion of strip shingles defined by cutouts.


Term used to describe a fastener not fully driven flush to the shingles surface.

Underwriters Laboratories, LLC.

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

Underside area of the overhang at the eave of the roof.

A layer of asphalt-saturated felt (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.


Area where two adjoining sloped roof planes intersect on a roof creating a “V” shaped depression.

Term used to describe moisture laden air.

Vapor Retarder
A material designed to restrict the passage of water vapor though a roof system or wall.

The internal angle formed

by the intersection of two sloping roof planes to provide water runoff.

Any outlet for air that protrudes through the roof deck, such as a 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.

Devices that eject stale air and circulate fresh air (e.g. ridge, roof, gable, undereave, foundation or rafter vents and vented soffit panels).


Warm Wall
The finished wall inside of a structure, used in roofing to determine how far up the deck to install waterproof underlayments at eaves.

The written promise to the owner of roofing materials for material related problems.

Waterproof Underlayments
Modified bitumen based roofing underlayments. Designed to seal to wood decks and waterproof critical leak areas.

Weather Stopper® Integrated Low-Slope Roofing System™
GAF’s complete roofing system and components.

Weather Stopper System Plus Ltd. Warranty Plus Limited Warranty
GAF’s next grade of enhanced warranty. Extended coverage for owners.

GAF’s granule-surfaced waterproof underlayment.

Woven Valley
Method of valley construction in which shingles from both sides of the valley extend across the valley and are woven t