Roof Terminology Guide

Attic: The open area above the ceiling and under the roof deck of a steep-sloped roof.

Asphalt Shingle: A roofing shingle made with a fiberglass mat coated with asphalt and surfaced with protective mineral granules. Asphalt shingles are one of the most commonly used residential roofing materials. 

Bundle: A packaged quantity of roofing shingles. The number of bundles required to cover one roofing square varies depending on the shingle manufacturer and product. 

Caulk: A sealant used around joints, flashing, penetrations, and other roof components to help prevent water intrusion. Roofing sealants should be compatible with the materials and application where they are used. 

Closed-Cut Valley: A roofing valley installation method where shingles from one roof slope extend across the valley while shingles from the adjoining slope are trimmed along the valley line. The valley flashing or underlayment beneath the shingles is not exposed. 

Collar: Also called a vent sleeve, a collar is a pre-formed flange placed over a vent pipe to seal the roof around the vent pipe opening.

Condensation: The change of water from vapor to liquid when warm, moisture-laden air comes in contact with a cold surface.

Counterflashing: Flashing installed over or into another piece of flashing to help prevent water from entering behind the roofing system. It is commonly used where a roof meets a chimney, wall, or other vertical surface.  

Course: A horizontal row of shingles or other roofing material installed across the roof from one side to the other. 

Cricket: A small peaked roof structure built behind a chimney or other roof obstruction to divert water around it and help prevent water from collecting on the uphill side. 

Cutout: The open portions of a strip shingle between the tabs.

Deck: The structural surface installed over the roof framing that provides the base for the roofing system. Roof decking is commonly made from plywood or OSB sheathing, although other materials may be found on older structures. 

• Plywood: Plywood is strong, durable, and light. It comes in many grades with ratings from A to D. Use only exterior grade plywood for decking. The thickness of plywood depends on the spacing of the rafters.
• OSB (Oriented Strand Board): OSB is cheaper than plywood, but not as strong as plywood, and does not hold nails as well as plywood. One side has a slip resistant coating and should be placed facing up.
• Tongue and groove 2-by-6: If a roof will be seen from the inside (no ceiling installed), tongue and groove is used. It is a wood decking that provides great insulation without additional rigid roof insulation in moderate climates. Also, the boards can be painted or stained on the inside to match the interior.
• Step sheathing: Step sheathing is used alone or in combinations with solid sheathing for installation of tiles or shakes. Step sheathing allows air circulations under the tiles by using 1-by-6 or 2-by-6 boards that are evenly spaced so that air can move under the tiles or shakes.

Dimensional Shingle: A shingle that is textured, overlayed, or laminated and designed to produce a three-dimensional effect. (Similar to Laminated shingle and Architectural shingle)

Dormer: A roofed structure that projects vertically from a sloped roof, typically containing a window. Dormers create additional interior space and require proper flashing where their walls and roof intersect the main roofing system. 

Downspout: A pipe for draining water from roof gutters. A downspout is also called a leader.

Drip Edge: Metal flashing installed along the edges of a roof to direct water away from the roof decking and fascia and into the gutter or away from the structure. 

Eave: The lower edge of a sloped roof that extends beyond the exterior wall of the building. Eaves help direct water away from the structure and commonly include components such as fascia, soffit, drip edge, and gutters. 

Edge Venting: The installation of a vent material along the roof edge (e.g., Starter Vent) as part of a ventilation system. Edge vent material should be used in conjunction with other venting material (e.g., ridge vent) as it not intended for use by itself.

Exposure: Portion of the shingle exposed to the weather. Exposure is measured from the butt of one shingle to the butt of the next.

Fascia: The vertical finishing board installed along the roof edge, typically behind the gutters. Fascia helps protect the ends of the roof framing and provides a surface for gutter attachment. 

Felt: A traditional type of roofing underlayment installed over the roof decking and beneath the shingles. Roofing felt provides an additional layer of protection against moisture during and after roof installation. 

Flashing: Thin pieces of metal or other approved material installed at roof joints, transitions, walls, chimneys, valleys, and penetrations to direct water away from vulnerable areas and help prevent leaks. 

• Valley flashing: This flashing is used in open valleys of the roof. Most often leaks are found in the valley flashings due to flashing that is nailed too tightly to the decking or shingles that are not trimmed far enough off the flashing.
• Plumbing vent flashing: Plumbing vent flashing prevents rainwater from running into holes cut for pipes in the roof. This flashing is sold according to the size of the vent pipe and the roof angle. Roofing material is installed over the flashing.
• Lead flashing: When working with tile roofs, lead flashing is used. In the case of a plumbing vent flashing, the lead flashing is actually molded to the shape of the tile’s surface. Then the top of the lead flashing is covered by the next tile to prevent water from seeping under the flashing.
• Step flashing: When a chimney or dormer wall intercepts the slope of the roof, step flashing is used. Step flashing is usually a metal piece that is bent in the middle, so that one end lays on the roof, and the other against the vertical wall of the dormer or chimney.

Gable: The triangular portion of an exterior wall formed between the two sloping sides of a roof. A gable roof typically has two roof slopes that meet at a ridge. 

Gable Roof: A type of roof containing sloping planes of the same pitch on each side of the ridge. A gable roof typically contains a gable at each end.

Gambrel: A type of roof containing two sloping planes of different pitch on each side of the ridge. The lower plane has a steeper slope than the upper. A gambrel roof usually contains a gable at each end, just like a standard gable roof.

Granules: Ceramic-coated colored crushed rock that is applied to the exposed surface of asphalt roofing products.

Gutter: A channel installed along the roof eave that collects rainwater from the roof and directs it into downspouts, helping move water away from the building and foundation. 

Hip: The angled exterior intersection formed where two sloping roof surfaces meet. Hip roofs typically have slopes on all sides of the structure rather than vertical gable ends. 

Hip Roof: A type of roof containing sloping planes of the same pitch on each of four sides. A hip roof contains no gables.

Ice Dam: A buildup of ice along the lower edge of a roof that prevents melting snow from draining properly. Water can back up behind the ice and potentially enter beneath the roofing materials. 

Ice & Water Shield: A self-adhering waterproof roofing underlayment installed in vulnerable areas such as valleys, eaves, and around roof penetrations to provide additional protection against water intrusion. 

Intake Ventilation: The part of a ventilation system used to draw fresh air in. Usually vents installed in the soffit or along the eaves of a building.

Intake Ventilation: The part of a ventilation system used to draw fresh air in. Usually vents installed in the soffit or along the eaves of a building.

Laminated Shingles: Asphalt shingles manufactured with multiple layers bonded together to create additional thickness, dimension, and a more varied appearance. They are commonly referred to as architectural or dimensional shingles.

Mansard Roof: A roof with two slopes on each of its four sides. The lower slope is much steeper than the upper slope, often approaching vertical. A mansard roof typically has no gables. 

Open Valley: A roof valley where shingles on both sides are cut back along the valley, leaving the metal valley flashing exposed. This design allows water to flow freely down the valley and off the roof. 

Overhang: The portion of a roof that extends beyond the exterior walls of a building. Roof overhangs help direct rainwater away from the walls and foundation while also providing protection from the elements. 

Pitch: The steepness or slope of a roof, commonly expressed as the number of inches the roof rises vertically for every 12 inches of horizontal run. For example, a 4/12 roof pitch rises 4 inches for every 12 inches of horizontal run. Roof pitch can affect material requirements, installation methods, drainage, and overall roof design. 

Pipe Boot (Roof Boot): A flashing component installed around plumbing vent pipes and other roof penetrations to create a watertight seal. Pipe boots are commonly made from rubber, metal, or a combination of materials and can become a source of roof leaks if they crack, deteriorate, or lose their seal. 

Racking: Roofing application method in which shingle courses are applied vertically up the roof rather than across and up. Not a recommended procedure.

Rafter: A structural framing member that runs from the roof ridge toward the eaves and supports the roof decking and roofing system. Rafters help transfer the weight of the roof to the exterior walls of the building. 

Rake: The sloped edge of a roof that runs from the eave to the ridge along the gable end of a home. The rake helps define the roofline and may extend beyond the exterior wall as part of the roof overhang. 

Re-roofing: Installing a new roof system on a building that is not new.

Ridge: The highest horizontal point of a roof where two sloping roof sections meet. The ridge is commonly covered with ridge cap shingles and may include a ridge vent to provide attic ventilation. 

Ridge Vent: A ventilation system installed along the peak, or ridge, of a roof that allows hot, humid air to escape from the attic. When properly balanced with soffit or other intake ventilation, a ridge vent helps improve attic airflow and reduce heat and moisture buildup. 

Rise: The vertical distance from the eaves line to the ridge.

Roof Deck (Roof Decking): The structural surface attached to the roof framing that provides the base for underlayment and roofing materials. Roof decking is commonly made from plywood or OSB and must be structurally sound to properly support the roofing system. 

Roof Plane: A single flat or sloped surface of a roof extending between features such as the ridge, eaves, rakes, hips, or valleys. A roof may consist of several individual roof planes depending on its design. 

Roof Vent: A component of a roof ventilation system designed to allow air to move into or out of the attic. Roof vents may include ridge vents, soffit vents, box vents, power vents, or other types and should be properly balanced between intake and exhaust ventilation. 

Run: The horizontal distance from the eaves to a point directly under the ridge.

Sheathing: The panels attached to the roof framing that form the structural surface of the roof deck. Roof sheathing is commonly made from plywood or OSB and provides the base for underlayment and roofing materials. 

Shed Roof: A roof containing only one sloping plane. It doesn’t have hips, ridges, valleys or gables.

Slope: The degree of roof incline expressed as the ratio of the rise, in inches, to the run, in feet.

Soffit: The finished underside of a roof overhang or eave. Ventilated soffits allow fresh outside air to enter the attic and work with exhaust vents, such as ridge vents, to help maintain proper attic ventilation and reduce heat and moisture buildup. 

Soil boot: A vent pipe that penetrates the roof.

Span: The horizontal distance from eaves to eaves.

Square (Roofing Square): A unit of measurement used in roofing equal to 100 square feet of roof area. Roofing materials such as shingles and underlayment are commonly estimated and ordered based on the number of roofing squares needed for a project. 

Starter Shingles (Starter Strip): Shingles or manufactured starter strips installed along the eaves and rakes before the primary roof shingles. They provide the first course of wind resistance and include an adhesive seal that helps secure the edges of the roofing system against wind uplift. 

Steep Slope Application: A roofing installation method used on roofs with a steep pitch where additional fastening, sealing, safety, or installation procedures may be required. Manufacturer installation requirements should be followed for the specific roofing material and roof slope. 

Step Flashing: Individual pieces of metal flashing installed where a sloped roof meets a vertical wall, chimney, or similar structure. The pieces are layered with each course of shingles to help direct water away from the roof-to-wall connection and prevent leaks. 

Tab: The exposed portion of a traditional strip asphalt shingle, typically separated by cutouts that create the appearance of individual shingles. Three-tab shingles have three tabs across each shingle. 

Three-Dimensional Shingles: Another term sometimes used for laminated, architectural, or dimensional asphalt shingles. These shingles are manufactured with multiple layers or tabs to create greater thickness, depth, and a more dimensional appearance than traditional three-tab shingles. 

Three-Tab Shingle: A traditional asphalt shingle manufactured with cutouts that create three individual tabs along its exposed edge. Three-tab shingles have a flat, uniform appearance and are generally thinner and lighter than laminated or architectural shingles. 

Underlayment: A protective layer installed over the roof deck and beneath the finished roofing material, such as asphalt shingles or metal roofing. Roof underlayment provides a secondary layer of protection against water intrusion and may consist of asphalt-saturated felt or synthetic materials. 

Valley: The internal angle formed where two sloping roof sections meet. Roof valleys collect and channel rainwater toward the eaves and gutters, making proper installation and waterproofing especially important in these areas. 

Vent: Any outlet for air that protrudes through the roof deck such as a pipe or stack. Any device installed on the roof, gable or soffit for the purpose of ventilating the underside of the roof deck.

Roofing Waste: Additional roofing material needed beyond the measured roof area to account for cuts, valleys, hips, rakes, starter courses, and installation requirements. The appropriate waste factor varies depending on the roof design, complexity, and roofing material. 

Waterproofing Underlayment: A self-adhering waterproof membrane installed beneath roofing materials in vulnerable areas such as valleys, eaves, roof penetrations, and around chimneys. It provides additional protection against water intrusion, including water that may back up beneath the roofing material. 

Wind Damage: Damage to roofing materials or components caused by wind forces. Signs may include lifted, creased, displaced, torn, or missing shingles, as well as damage to flashing, ridge caps, vents, or other roof components. Wind damage should be evaluated based on the specific roofing material, installation, and observed conditions. 

Wind-Driven Rain: Rain that is forced by wind against or beneath roofing materials and building components. Properly installed shingles, flashing, underlayment, and roof penetrations work together to help prevent wind-driven rain from entering the roofing system. 

Wind Uplift: The upward force created when wind pressure acts on a roofing system, particularly along roof edges, corners, ridges, and other vulnerable areas. Proper fastening, starter shingles, and manufacturer-approved installation methods help the roofing system resist wind uplift. 

Woven Valley: A roof valley installation method in which shingles from both adjoining roof slopes are alternately woven across the valley. When properly installed with compatible shingles, the woven pattern creates a continuous shingle surface that directs water down the valley.