What are the roofing terms I need to know to better understand my roofing needs?

There are many different terms that contractors use that can leave a homeowner dazed, confused, and feeling intimidated. Roofing, in particular, has a language of its own, and in an effort to quell that sense of intimidation a bit, we here at Roof Right Now have put together a simple A-Z list of commonly used vocabulary in the world of roofing.

Absorption: How a material accepts or rejects water.

Aluminum: A non-rusting, easily pliable metal, used in roofing as flashing and around the perimeter as a drip edge.

Apron Flashing: A term used for the material, usually metal, that helps join a roof to a vertical wall

Architectural Shingle: A shingle made of asphalt, fiberglass, and other composite materials that is designed to look three dimensional

Base Flashing: Strips of ice and water shield, or metal used to seal around protrusions in the roof or roof-to-vertical intersections.

Bitumen: A material typically composed of asphalt and tar, common in most ice and water shield products.

Blocking: Sections of wood built into a roof, usually above the roof deck and below the flashing and membrane.

Buckle: A displacement of the roof membrane in an upward direction

Barrel Roof: A roof configuration with a partial cylindrical shape to it.

Base Ply: The primary ply of roofing material in a roofing system.

Batten: A strip of wood usually fastened to the structural deck for use in attaching a primary roofing system such as tile.

Birdstop: A barrier placed under the lower course of round Spanish type tile, to keep birds from making nests in a roof.

Boot: A piece of preformed material, sometimes made of silicone, other times made of metal, that is meant to protect roof protrusions from water or other debris.

Buckle: A long, tented displacement of roof membrane, most common at deck joints (places where sheets of plywood meet)

Cap Sheet: The top layer of rolled roofing, usually very granular in its composition, and often times self adhering.

Caulking: The process of sealing a roof joint or junction point.

Cladding: The material used on a building’s exterior wall enclosure, usually brick, vinyl siding, aluminum, or wood

Composition Shingle: A shingle made of asphalt, fiberglass, and other filler materials such as limestone.

Coping: The covering piece on top of a wall that is exposed to weather, usually made from metal, masonry or stone.

Copper: A natural weathering material used in metal roofing.

Counter Flashing: A formed metal sheet secured into a groove that is typically cut into a chimney. Counter flashing is a second layer of flashing that will have either membrane or metal flashing beneath it.

Course: Each row of the roofing system, with the first course starting at the eave or edge of the roof, and the final course ending at the ridge of the roof.

Coverage: The surface area covered by a specific quantity of a particular material.

Cross Ventilation: When air moves between vents in a roof or attic.

Deck: The wood upon which the entire roofing system is built. It is traditionally made of plywood and supports all the shingles and underlayments.

Deflection: The bowing or sagging of a roof due to weight.

Delamination: The separation of plywood sheets or other laminated components of a roofing system, usually due to water.

Dormer: A framed projection through the sloping plane of a roof.

Downspout: a conduit used to channel water from the gutters to the ground level

Drip Edge: A pre formed metal edge designed to protect the edge of the roof from corrosion and water adhesion.

Eave: The edge of a roof that extends beyond the supporting wall. The eaves are the edges of the roof that are furthest from the ridgeline.

Expansion Joint: A structural separation between two building elements that allows free movement between the elements without damage to the roofing system.

Extrusion: The process used to force a material through a die.

Eyebrow: A small shed roof protruding from the main roof or located on the side of a building below the level of the main roof.

Fascia: Term used to describe the material that covers or caps the trim board at the eave edge of the home. Typically this is done with aluminum or vinyl capping.

Felt: A flexible sheet used as the primary underlayment for most roofs. Felt is a generic term that can refer to something as simple as old fashioned, tar-paper or it can refer to the more complex polypropylene based synthetic underlayments.

Flashing: Components used to weatherproof or seal the roof system edges at perimeters, penetrations, walls, expansion joints, valley, drains, and other places where the roof covering is interrupted.

Gable: A triangular portion of the end wall of a building.

Granule: A small aggregate, naturally or synthetically colored, used to surface shingles and cap sheets as a way to protect the surface of the roof from the heat.

Gutter: A trough-style catch all designed to channel water from the eave edges of the roof safely into downspouts and away from the home.

Hipped roof: A roof with inclined ends as well as sides

Ice and Water Shield: A self-adhering bituminous membrane that can be applied to the valleys, edges and around protrusions of a roof to provide added protection against leaks.

Ice dam: An accumulation of ice that forms when a roof surface transitions from warm to cold, often caused by refreezing of melting ice at eave edge of a roof.

Joist: Metal or wood beams arranged parallel from wall to wall to support a building’s floor or ceiling. They are typically 16 inches away from one another.

Live loads: Temporary loads that the roof structure must be designed to support, as required by local building codes. Snow and rain are typical examples of live loads.

Membrane: A flexible or semi-flexible material, which functions as the waterproofing component in a roofing system. Ice and water shield are examples of self-adhering membranes in most roofing systems.

Metal flashing: Metal accessory components used to weatherproof terminating roof covering edges.

Organic felt: An asphalt roofing base material manufactured from cellulose fibers. Often times it is referred to as tar-paper.

Organic shingle: a shingle made of formerly living (organic) materials such as paper, cellulose, wood fiber, or other materials saturated with asphalt to make it waterproof. A top coating of adhesive asphalt is applied and ceramic granules are then embedded.

Rafter: Sloped structural members, typically extending from the ridge of a roof to the eave.

Rake: The sloped edge of a roof at or adjacent to the first or last rafter.

Ridge: The highest point on the roof.

Roofing System: The entirety of a well done roofing job, including wood decking, drip edge, ice and water shield, primary underlayment, starter shingle, shingles, proper vents, flashing, etc.

Roof slope: The angle of a roof’s surface, referred to in the algebraic language of rise/run, with 12 inches as the “run” here in the United States because of 12 inches.

R-Value: The measure of a material’s resistance to heat flow. The higher a material’s R-value, the more it insulates.

Self-sealing shingle: An asphalt shingle that is manufactured with a strip of adhesive on its underside so that it fastens or sticks to the shingle beneath it to prevent blow-offs.

Shingle: Roofing material installed in overlapping rows or courses.

Skylight: A roof accessory designed to admit light into the home.

Slate: A hard rock consisting mainly of clay minerals that is used on some upscale roofs.

Snow guard: A series of devices designed to hold snow in place and prevent sudden snow or ice slides from the roof, most common on metal roofs.

Soffit: The underside of any exterior overhanging section of a roof eave.

Standing seam: A metal roof system that consists of overlapping or interlocking seams.

Starter course: The first layer of roofing applied along a horizontal line beginning at the eave of a roof.

Static load: Any load that does not change.

Substrate: The surface upon which the roofing or waterproofing membrane is applied.

Tab: The exposed portion of strip shingles and defined by cut-outs.

Underlayment: An asphalt-saturated felt or other sheet material (may be self-adhering) installed between the roof deck and the roof system, usually used in a steep-slope roof construction.

Valley: The internal angle formed by the intersection of two sloping roof planes.

Vapor retarder: Material installed to impede or restrict the passage of water vapor through a roof assembly.

Vent: An opening designed to convey air, heat, or water vapor from inside a building to the atmosphere.

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