Most Common Roofing Terms You Should Know

As licensced roofing contractors we find that it is extremely helpful when speaking with a potential customer that they are able to make an informed decision based on knowledge and understanding of what it will take to repair or replace their roof.  We decided to help with this knowledge and understanding by posting our own most common residential and commercial roofing terms and their definitions.  This list is not comprehensive by any means but it will give you enough information to make an informed decision.

As always, should you have any questions or concerns, please do not hesitate to contact us.


Rooftop fungus that can leave dark stains on roofing.

Apron Flashing

Metal flashing used at chimney fronts.


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


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.


When a wrinkle or ripple affects shingles or their underlayments.

Counter Flashing

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


The surface (usually plywood, wood boards, or planks) to which roofing materials are applied.


A raised smaller structure projecting from a larger sloped roof plane, usually with a window.

Drip edge:

An L-shaped strip (usually metal) installed along roof edges to allow water run off to drip clear of the deck, eaves and siding.


The roof edge from the fascia to the structure’s outside wall. In general terms, the first three feet across a roof is termed the eave.


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


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


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

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 used to prevent the seepage of water around any intersection or projection in a roof system, such as vent pipes, chimneys, valleys and joints at vertical walls.

Gable Roof

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


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


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

Hip Roof

A roof with four roof planes coming together at a peak and four separate hip legs.

Ice Dam

When a snow load melts on a roof and re-freezes at the eave areas. Ice dams force water to “back-up” under shingles and cause leakage.


Slatted devices installed in a gable or soffit (the underside of eaves) to ventilate the space below a roof deck and equalize air temperature and moisture. Oriented strand board (OSB): Roof deck panels (4 by 8 feet) made of narrow bits of wood, installed lengthwise and crosswise in layers, and held together with a resin glue. OSB often is used as a substitute for plywood sheets.


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


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


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.


Method of installing shingles in a straight up the roof manner.


The supporting framing to which a roof deck is attached.


The inclined edge of a roof over a wall.


The top edge of two intersecting sloping roof surfaces.


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


The boards or sheet materials that are fastened to rafters to cover a house or building.

Shed Roof

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

Side Walls

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


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


Metal flashing pieces installed at sidewalls and chimneys for weatherproofing.


The common measurement for roof area. One square is 100 square feet (10 by 10 feet).


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


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


Asphalt-based rolled materials designed to be installed under main roofing material to serve as added protection.


The angle formed at the intersection of two sloping roof surfaces.


Term used to describe moisture laden air.

Vapor retarder:

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


We are always here to help you make informed decisions regarding your roofing needs.  We offer free roof inspections and estimates so call 1-866-PRESTO-7 (1-866-773-7867 ) today to schedule yours!

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