The ABC’s of roofing, brought to you courtesy of Downriver Roofers

When you’re in the market for a new roof, sometimes the terms in the industry can be a bit confusing, which is why Downriver Roofers developed this handing roofing term guide for you. We are a full service roofing contractor in the Downriver, Michigan area, ready to serve your needs, anytime, day or night. We specialize in roofing repairs, roof maintenance, protective roof coatings, roof ventilation and upgrade, new roof installation, roof ridge and hip replacement, roof inspections, roof shoveling, re-roofs, tear-offs, and much more. If you’ve got a roofing emergency, we are the ones to call first.

We offer a 100% money-back guarantee, and only use GAF, CertainTeed roofing materials on all our commercial and residential roofing projects. Keep this guide nearby so you can reference it when you call us for your free roof inspection.

Common Roofing Terms


Fungus found on the roof, resulting in dark stains.

Angled Fasteners

Roofing tools including staples and nails, driven into decks at an angled position.

Apron Flashing

Metal flashing that diverts to a chimney front.


Asphalt Roofing Manufacturers Association, an official industry organization of roofing manufacturers.


Brownish-back substance and waterproofing agent used in various roofing materials.

Asphalt Concrete Primer

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

Asphalt Plastic Cement

Asphalt based roofing sealant and adherent material, meeting ASTM D4586 Type I or II. Also known as blackjack, mastic, bull, and roof tar.


American Society for Testing and Materials, an organization that establishes standards for building and roofing materials.
Back Surfacing

Granular material located on back of shingles, designed to separate roofing materials during storage and delivery.


Imperfections such as pimples or bubbles in roofing materials, usually caused by trapped moisture.

Shingles that fall of a roof deck cause by high winds.

Effect of rippled or wrinkled appearing shingles or their underlayments.
Closed Cut Valley

Also known as shingle valley installation, wherein one layer covers another, and the top layer is cut to match the valley lines.


Ventilation products endorsed by GAF.

Counter Flashing

Used for rooftop flashing systems, consisting of metal or siding material.

Country Mansion®

Limited lifetime warranty shingle products endorsed by GAF.


Used to divert water near chimneys and other large roof projections, also known as a peaked water diverter.


Result of poorly installed or manufactured shingles over an existing roof that form a curl or cup.

Plywood, wood boards, or plank materials upon which a new roof is installed.

Deck Armor

Deck Armor – premium breathable roof deck protection, serves to provide a vital extra layer of protection between your shingles and your roof deck — to help prevent wind or water-driven rain from infiltrating under your shingles and causing damage to your roof structure or to the inside of your home.


An addition to a roof,  raised and extended over a larger roof plane.

Drip Edge

Structure serves to keep shingles off the deck at edges; extends shingles over eaves and gutters.
Dubl-Coverage Mineral Guard®

Provides double coverage over roof decks; made of roll roofing material with 19″ selvage edge.

Roof edge from fascia to outside wall; first three feet off a roof’s edge.
End Laps

Area where rolled roofing material ends on a roof, and is overlapped by another section.

Engineered Wood Association; establishes standards for all types of U.S. plywood.


Part of roofing material that is exposed and vulnerable to the elements.

Materials used to secure roofing to deck (nails or staples).

Federal Housing Authority; establishes official construction standards in the U.S.

Fiberglass Mat

Durable, resilient mats used in roofing materials, made of fiberglass.


Metal pan located up or down a roof slope near flashing materials; typically at plumbing and chimney vents.


Waterproofing roofing materials used to protect any projections.

Flashing Cement

Specialized sealant used around flashing areas, usually thicker than plastic cement.
Gable Roof

Traditional roofing style; consisting of two peaked roof planes culminating at a ridge line equal in size.


GAF manufactured cant strips used to deflect water from flashing areas.

Golden Pledge®

GAF’s most powerful limited warranty for shingles.

Grand Sequoia®

GAF manufactured shingle characterized by wood shake look.

Grand Slate™

GAF manufactured shingle with slate form.


Consist of broken or crushed rock coated with ceramic and fired, serves as a top shingle surface.

Method enables sealing of shingles on extremely steep slopes, good for high wind areas and installing in cold weather.
High Nailing

Process of nailing or fastening shingles above manufacturer’s designated nail area.

Hip Legs

Characterized as down-slope ridges on typical hip roofs.

Hip Roof

Roof consisting of four roof planes joining together at a peak with four individual hip legs.
Ice Dam

Forms when snow melts on a roof and then re-freezes near eaves, causing water to accumulate under shingles and form leaks.

“L” Flashing

Uninterrupted metal flashing made of metal; used at horizontal walls and in an “L” shape.
Laminated Shingles

Laminated shingles consisting two separate pieces such as GAF Timberline® Series, Country Mansion® and Grand Sequoia® Shingles; also known as dimensional and architectural shingles.


Area where roll roofing or rolled underlayments overlay during application.



Also known as self-adhering low-slope roofing, Liberty™ brand systems are installed without the use of torches, hot asphalt, open flames, or solvent-based adhesives.

Low Slopes

Roof pitches measuring less than 4:12, requiring special installation practices.



Roof style featuring with a highly vertical roof plane that joins a roof plane of less slope at the peak.


Term for base material of shingles and specific rolled products.

Modified bitumen

Rolled roofing material made of polymer modified asphalt and fiberglass or polyester  reinforcement.


Made of mortar, sand, mortar, water and limestone used to bond a chimney’s bricks.
Nail Guide Line

Visible, painted line on laminated shingles, used to assist in correct placement of fasteners.


Term for a nail that is not fully driven.


Process of installing a second layer of shingles to align original roof and avoid shingle cupping.


National Roofing Contractors Association, an official U.S. organization of roofing contractors.
Open Valley

Valley installation consisting of using metal down the valley center.

Organic Mat

Material consisting of  recycled paper and wood pulp.

Organic Shingles

Organic (made from paper mats) shingles.


Oriented Strand Board. Decking made of laminating glues and wood chips.


Fasteners driven through roofing material too forcefully, resulting in material breaking.


When an installed shingle courses higher than intended exposure.
Quarter Sized

Typical size of hand sealant dabs, about as big as a U.S. quarter.

Method used to install shingles straight up on a roof.
Rake Edge

Vertical edge of typical gable type of roof planes.

Release Film

Plastic sheet installed behind WeatherWatch® and StormGuard® underlayments.
Rigid Vent

Known as durable plastic ridge venting material.

Roof Louvers

Rectangular shaped rooftop vents, also known as mushroom vents, box vents, soldier vents, and airhawks.

Roof Plane

Roofing area consisting of four separate edges.

Exposed section of double thickness on Timberline® Series brand shingles – also known as dragon teeth.


Sealant installed on shingles, activated by the heat and sun to seal shingles together.

Non-exposed area on rolled roofing without granules, developed for sealant and nail placement.

Shed Roof

Roof design consisting of a single roof plane; does not tie in with any other roofs.

GAF manufactured shingle underlayment, made of fiberglass backing to minimize buckles and wrinkles.

Side Laps

Area on rolled material that overlaps underlaying rolled material; also known as selvage edge.

Side Walls

Place where a vertical roof plane joins with a vertical wall, found on the sides of dormers, etc.

Soffit Ventilation

Located under eaves or at roof edge, also known as intake ventilation.

GAF Shingle & Accessory Ltd. Warranty

GAF’s widely known standard shingle limited warranty.

Starter Strip

First area of roofing installed, usually gleaned from primary roof material.

Steep-Slope Roofing

Any slopes higher than 4/12.


Metal flashing material installed at chimneys and sidewalls used for weatherproofing.


GAF manufactured waterproof underlayment.

Bottom piece of typical shingle divided by shingle cut-outs.


Process of removing an existing roof down to roof deck.


Can be seen when shingles reflect uneven surface, revealing buckles, etc.
Timberline® Series

GAF’s brand name for laminated wood-shake-designed shingles.


GAF manufactured and endorsed Ridge and Hip Shingles.


Happens when a roof plane joins with another roof plane revealing a dissimilar slope or pitch.

When a fastener is not completely driven flush to surface of shingles.


Asphalt-based rolled roofing materials developed to be installed beneath primary roofing material offering enhanced protection.

Area where two contiguous sloped roof planes connect on a roof resulting in a “V” molded depression.


Moisture filled air.
Warm Wall

Completed wall inside a structure, used in roofing industry to ascertain how far up deck to install waterproof underlayments near eaves.


Written agreement to roofing materials owner in case material related issues arise.
Waterproof Underlayments

Modified bitumen made roofing underlayments, used to seal to wood decks and waterproof chronic leak areas.

Weather Stopper® Integrated Low-Slope Roofing System™

GAF manufactured comprehensive components and roofing system.

Weather Stopper System Plus Ltd. Warranty
Plus Limited Warranty

GAF’s next highest grade of enhanced warranty, providing extended coverage for home or business owners.


GAF manufactured granule-coated waterproof underlayment.

Woven Valleys

Process of installing valleys typified by laying one shingle over the other on valley center.


Getting started is easy

Call us today at 734-548-9919 and speak with one of our licensed, insured and certified roofing professionals. Roofing maintenance and installation is what we are known for, which is why we’re are always top-rated by our customers. If you live in Downriver, MI, call Downriver Roofers today, we are a reputable roofing company that is affordable and dependable. Check out our website at for more information, and don’t forget to like us on Twitter and Facebook, too.