Roofing Terms Explained in Plain English

Quotes and inspection reports are full of trade words. These definitions are short on purpose. For the questions to put to a crew once you can follow the vocabulary, see the hiring guide.

Architectural shingle

A thicker asphalt shingle made from layered pieces, which gives the roof a textured look. Also called a dimensional or laminated shingle. It is the common upgrade from the flat, single-layer three-tab shingle.

Attic ventilation

Airflow through the attic, usually air entering at the soffits and leaving near the ridge. It keeps the roof deck drier and helps limit heat buildup and ice dams. Poor ventilation is a frequent cause of early shingle wear.

Counter-flashing

Metal that overlaps the top edge of base flashing, usually set into a masonry joint or tucked under siding. It sheds water away from the joint where the roof meets a wall or chimney.

Cricket

A small peaked structure built behind a chimney or other wide obstruction on the uphill side. It sheds water around the obstruction instead of letting it pool there. Also called a saddle.

Decking

The sheets or boards fastened to the rafters or trusses that the roofing material is attached to. Also called sheathing. Rotted decking is usually found only after the old roof is removed, so a quote should say how it will be priced.

Dormer

A framed structure that projects from a sloped roof, usually holding a window. Its walls and valleys add flashing details, which are common leak points.

Drip edge

L-shaped metal fastened along the eaves and rakes. It guides water into the gutter and keeps it from creeping back under the roof edge. Many local codes require it.

Eave

The lower edge of a sloped roof, the part that overhangs the wall. Water runs off the roof at the eave and into the gutter.

Fascia

The board that runs along the eave, behind the gutter. Gutters are fastened to it, and it is among the first parts to rot when water backs up.

Flashing

Thin metal, or sometimes a flexible membrane, that directs water away from joints and openings: chimneys, walls, vents, skylights and valleys. Flashing failures cause a large share of leaks.

Gable

The triangular wall section formed where two sloping roof planes meet. A gable roof has two planes and a ridge between them.

Granules

The small mineral particles on the surface of an asphalt shingle. They shield the asphalt from sunlight. Heavy granule loss, seen as dark patches or grit in the gutters, signals an aging shingle.

Hip

The outward sloping line where two roof planes meet at an exterior corner. A hip roof slopes on all four sides.

Ice and water shield

A self-adhering membrane laid over the deck in vulnerable areas, such as eaves, valleys and around penetrations. It seals around fasteners and guards against water pushed under shingles by ice dams.

Ice dam

A ridge of ice that builds up at the eave when heat escaping from the house melts snow on the roof and the meltwater refreezes at the colder edge. Trapped water can then back up under the shingles.

Overlay

Installing a new layer of roofing over the existing one instead of removing it. Whether it is allowed, and how many layers are permitted, depends on local code and the manufacturer’s instructions. Compare it with a tear-off.

Penetration

Anything that passes through the roof: a vent pipe, a chimney, a skylight, an exhaust fan. Each one needs flashing and each is a place to look first when tracing a leak.

Pipe boot

A collar, usually rubber or neoprene around a metal base, that seals a plumbing vent pipe where it exits the roof. The rubber cracks with age, so boots often need replacing before the shingles do.

Pitch

How steeply a roof slopes, written as rise over run. A 6 in 12 pitch rises 6 inches for every 12 inches of horizontal run. Pitch affects which materials can be used and how much surface a roof has; the roof area estimator uses it to convert a footprint into roof area.

Rafter

A sloped framing member that runs from the ridge down to the wall and supports the decking. Trusses do the same job as a factory-built assembly.

Rake

The sloped edge of a gable roof, running from the eave up to the ridge. Where the eave is the low edge, the rake is the side edge.

Re-roof

Any job that puts new roofing on an existing house, either as a full tear-off or an overlay. Often used loosely to mean replacement.

Ridge

The horizontal line at the top where two roof planes meet. Ridge caps cover it.

Ridge vent

A vent installed along the ridge that lets warm air leave the attic. It works together with intake vents at the soffit; a ridge vent with blocked intakes does little.

Roofing square

The unit roofers use for quantities: 100 square feet of roof surface. A roof measured at 2,400 square feet is 24 squares.

Scupper

An opening in a parapet wall or low edge that lets water drain off a flat roof. It often empties into a downspout.

Sheathing

Another word for decking.

Soffit

The underside of the eave overhang. Vented soffits let air into the attic.

Starter strip

A row of shingles or a purpose-made strip installed along the eave before the first full course. It seals the lower edge and helps stop wind lifting the first row.

Step flashing

Small, individual pieces of bent metal woven into the shingle courses where a roof meets a vertical wall. Each piece overlaps the one below, so water is led down and out over the shingles.

Tab

The exposed section of a shingle between the cutouts. A three-tab shingle has three equal tabs and a flat profile.

Tear-off

Removing the existing roofing down to the deck before installing new material. It lets the crew inspect and repair the decking. Quotes should state whether they assume a tear-off.

Truss

A prefabricated triangulated frame that carries the roof load and replaces individual rafters and ceiling joists. Trusses should not be cut or altered without an engineer’s approval.

Underlayment

The layer between the deck and the shingles. It gives a second line of defense against wind-driven rain. Types include felt and synthetic sheets, and manufacturers specify which one a warranty requires.

Valley

The inside angle where two roof planes meet and send water toward each other. Valleys carry heavy water flow, so they are lined with extra protection and checked closely for debris.

Waste factor

The extra material ordered above the measured area to cover cuts, starter courses and mistakes. The figure depends on the roof’s complexity and the material.