Answer Guide

TYPES OF ROOF SYSTEMS

Built-up – A continuous, semi-flexible roof membrane assembly, consisting of plies of felt and/or rolled roofing material between which alternating layers of tar and/or bitumen are applied. (Ex: Tar & Gravel, Cap Sheet roof systems)

Cap Sheet – A built-up roof system with a top ply of a rolled mineral cap sheet.

Clay Tile –Clay tiles are formed by baking plates of molded clay into uniform pieces. The tiles are usually hung by wire, installed in an even pattern over felt underlayment. These tiles come in various shapes and styles.

Concrete Tile – Tiles made from portland cement, sand and water are hung on wooden battens, installed over a felt underlayment and solid sheathing. These tiles come in various shapes and styles. The tiles come in a standard weight, which is used in new construction and a lightweight concrete, which is used in reroofing.

Composition Shingle – Normally a flat 3-tab composition shingle roof system. These shingles are asphalt based with a fiberglass mat and are covered with small sand-like granules.

Dimensional Composition Shingle (Laminated Shingles)- These shingles are multi layered for built-up or rustic appearance. They are also asphalt based with a fiberglass mat. They come in numerous styles, colors and designs.

Foam - A layer of polyurethane foam installed over an existing built-up roof system with an elastromeric type coating.
 
Lightweight Concrete Tile – see Concrete Tile

Simulated Shake – This is a man-made product which is similar in appearance to wood shakes. These products are usually composed of wood fibers and cementitious materials, are lightweight and carry a class A fire rating. (Ex: American Cemwood, FireFree, Hardi-Shake. Permatek, etc.)

Simulated Tile –This is an interlocking galvanized steel panel roof system. These steel panels are coated with earthstone granules, an acrylic resin and acrylic overglaze. These panels were nailed to wood framing, which was installed over either the original roof system or the roof sheathing.

Slate – Roofing slate is a dense, tough, durable rock material that is practically nonabsorbent. Slate roof systems tend to look like tile roof systems and are installed in similar ways.

Steel – A roof system constructed of cold-steel sheets (panels) with ribs in each panel to provide strength and rigidity. The panels are available in several depth and gauges

Tar and Gravel – a built-up roof system with gravel (aggregate) embedded in the top flood coat.

Torch-down - A continuous, semi -lexible roof membrane assembly, consisting of two plies. The first ply is the base felt upon which the torch down bituminous product is applied. Application is done by a specialized flame torch which melts the bitumen that is part of the rolled product.
 
Wood Shake – A wood shake is a wood roofing product that is split from a log and shaped by the manufacturer for commercial use. The wood shakes are interwoven with a shakefelt underlayment to form the roof system. Most shakes are treated with a fire-retardant; however the fire rating of the roof system cannot be determined by a visual inspection. Shakes are graded based on the thickness of the butt ends. Medium shakes are ½”; Heavy Shakes are ¾”, while Jumbo Shakes are 1” thick.

Wood Shingle – A wood shingle is a milled wood product manufactured to a uniform length and width.

ROOF TERMS

Battens – 1” X 2” wood strips installed on tile roofs from which the tiles are hung.

Bitumen – a generic term used to denote asphalt or coal tar used for roofing purposes.

Blind Nailing – the practice of nailing the back portion of a roofing product in a manner where the nails are not exposed to the weather.

Blister – an enclosed pocket of air trapped between two or more layers of felt or roofing material.

Cap Sheet – a granule-surface coated sheet of rolled roofing product used as the top ply in a built-up roof system.

Condensation – the conversion of water vapor or other gases to liquid as the temperature drops or the atmospheric pressure rises.

Counterflashing – a flashing and/or roofing material used to cover existing base flashing at wall, chimney and other perpendicular areas.

Crack – a separation or fracture occurring in a roof material, roof sealant or roof system.

Cricket – a relatively small, elevated area of roof constructed to divert water around a chimney or other projection in the roof structure.

Delamination – separation of the piles in a roof membrane or in a wood product such as plywood.

Diverter – An “L” shaped piece of metal flashing used to divert water run-off away from one specific area of the roof to another.

Drainage – the natural flow of water off the roof system.

Elastromeric – a rubber like synthetic polymer that will stretch when pulled and will return to its regular shape when released. Used in deck, balcony and roof coatings.

Exposure – the traverse dimension of a roofing element not overlapped by an adjacent element in any roofing system.

Felt – a flexible rolled sheet of material used beneath most roofs materials as a moisture and/or condensation barrier.

Flashing – the material and/or system used to seal the existing roof system at walls, expansion joints, drains, chimneys, skylights and other areas. See Metal Flashings.

Flood Coat – the top layer of asphalt and/or bitumen into which the aggregate (gravel) is embedded.

Gravel – course, granular aggregate (rock) with pieces large than sand grains.

Gravel Stop – a flanged piece of metal designed to provide a continuous finished edge for roofing materials and to prevent loose aggregate (gravel) from washing off the roof.

Hip – the pointed elevation line of a roof formed by two roof plains.

Mastic – an asphalt-based cement-like product used as a sealant in various areas of different roof types.

Membrane – 1) a flexible roof covering or waterproofing layer whose primary function is the exclusion of water. 2) A cloth-like product used as reinforcement with roof sealant products.

Mortar – the cement type product that is used to secure various tile pieces to each other.

Nosing – the metal strip used on rake and/or drip edges to provide a continuous finished edge for roofing materials.

Pitch – the slope of a roof expressed in the number of vertical units of rise per horizontal units of run. (Ex: 4 and 12 is the normal or most typical roof pitch)

Pipe Collar – the metal flashing which is integrated within the roof system and fits over plumbing pipes cut through the roof. Also referred to as Pipe Jack.

Plastic Cement – see Mastic

Ply – a layer of felt in a built-up roof membrane system. Ex: A three-ply system has three plies of felt and/or roofing material.

Rake Edge – the slope edge of a roof at the first or last rafter.

Ridge – the top edge or peak of a roofline.

Rolled Roofing – a prepared organic felt material with a sand granule surface. See Cap Sheet.

Roof System – a system of interacting roof components designed to weatherproof and, normally, to insulate a building’s top surface.

Rubber Hoods – a flexible circular piece of rubber material used to counterflash and seal a pipe collar.

Saddle – a metal flashing designed to wrap around specific roof penetrations. (chimneys, skylights, etc.)

Sealant – a mixture of polymers, fillers and pigments used to fill and seal joints where moderate movement is expected.

Shingle – a small unit of prepared roofing material designed for installation with other like units.

Slope – see Pitch

Square – the term used to describe 100 square feet of roof area.

Starter Material – the roofing product that is laid beneath the first course of roof material in order to cover the existing substructure and to give the first course of material the proper rise.

Step Shingle – an “L” shaped piece of metal flashing used at roof-to-wall areas and interwoven with the roof shingles.

Tar – a brown or black bituminous material used in built-up roof systems.

Valley – the area where two sloping plains join at an angle.

Valley Metal – a metal flashing installed in some valley areas to form a natural drain.

Vent – an opening designed to convey water vapor or other gases from inside a building to the outside.

Vent Flashing – a metal flashing integrated with the roof system to cover a designed hole and/or fixture in the roof.

Vent Seals – the area between an existing roof penetration and the overlapping metal flashing.

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