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Horsefly Construction

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Common Roofing Terms



Adhere: The clinging of one surface to another.

The cracking of the surface bitumen on a built-up roof, producing a pattern of cracks that resemble an alligator’s skin.

Architectural Panel:
A metal roof panel that usually requires solid decking underneath.

Architectural Shingle:
Shingle that provides a dimensional appearance.

Area Divider:
A raised, double wood member attached to a properly flashed wood base plate that is anchored to the roof deck.

The open area above the ceiling and under the roof deck.

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The practice of blind-nailing roofing felts to a substrate.

A fine mineral material on the back side of roofing materials.

Base Flashing: 
The system used to seal membrane edges where the membrane intersects vertical surfaces.

Base Ply:
The lowermost ply of roofing material in a roof membrane assembly.

A strip of wood usually fastened to the structural deck for use in attaching a primary roof system.

A waterproofed barrier that protects the substrate.

A continuous seal for preventing bitumen from leaking down into or off of a building.

The installation of nails so that they are not exposed to the weather in the finished roofing system.

A pocket of air mixed with water or solvent vapor, trapped between impermeable layers of felt or between the felt and substrate.

Wood built into a roof assembly used to stiffen the deck around an opening, act as a stop for insulation or for use as a nailer.

Bonding Agent:
 A chemical agent used to create a bond between two materials.

A preformed cylinder used to flash pipe penetrations.
(1) A piece of equipment used for forming metal. (2) A straight bend in a metal sheet.

A section of membrane that is unsupported by a structural substrate.

A long, tented displacement of a roof membrane.

An individual package of shingles or shakes.

Butt Joint:
A joint in which two separate, adjacent pieces of material are abutted.

Butyl Tape:
A sealant tape.

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A slight convex curve of a surface.

Cant Strip: 
A triangular-shaped strip of material used to ease the transition from a horizontal plane to a vertical plane.

Cap Flashing: 
A material used to cover the top edge of base flashings or other flashings.

Cap Sheet: 
A granule-surfaced membrane often used as the top ply of roof systems.

A product applied to cracks or holes to prevent moisture access.

The point where the converging slopes meet.

Cladding: A material used to cover the exterior walls of a building.

A continuous metal strip used to secure metal roof components.

A small cleat.

Closed-Cut Valley: 
A method of valley application in fiberglass or asphalt shingle roof installations in which shingles from one side of the valley extend across the valley while shingles from the other side are installed over the top of those and then trimmed back from the valley centerline.

Closure Strip:
A material used to close openings created by joining metal panels or sheets and flashings.

A layer of material that is spray, roller, or brush applied over a surface for protection.

Collector Head:
A component used to direct water from a through-wall scupper or a gutter to a downspout.

A vertical structural member placed on a footing or foundation used to support horizontal above-ground building components.

Combing Ridge:  
Installation of finishing slate at the ridge of a roof whereby the slates on one side project beyond to the apex of the ridge.

Composition Shingle:
A type of shingle used in steep-slope roofing.

Conductor Head:
A component used to direct water from a through-wall scupper or a gutter to a downspout.

A material used to cover the top of a wall and protect it from the elements.

A horizontal projecting part that crowns the wall of a building.

Counter Batten:
Wood strips installed vertically on sloped roofs over which horizontal battens are secured.

Formed metal sheeting secured to walls, curbs, or other surfaces to protect the top edge of base flashings from exposure.

(1) The term used for each row of roofing material that forms the roofing or flashing system; (2) One of multiple layers materials applied to a surface.

A heavy bead of sealant material installed at the point where vertical and horizontal planes meet. It is used to eliminate the 90° angle.

Cover Plate:
A metal strip sometimes installed over the joint between formed metal pieces.

Movement of roof membrane causing the roof system to be deformed.

A roof component used to divert water around roof penetrations and projections.

Cross Ventilation:
The effect of air moving through a roof cavity between vents.

A relatively small roofed structure set on the ridge of a main roof area.

(1) A raised member used to support equipment above the level of the roof surface. (2) A raised roof perimeter that is relatively low in height.

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Dead Loads: 
Non-moving rooftop loads, such as mechanical equipment, the roof system and the roof deck.

The structural component of the roof of a building which provides the substrate to which the roofing system is applied.

Dimensional Shingle:
A shingle that is textured, or laminated to produce a three-dimensional effect.

A framed projection through the sloping plane of a roof.

A conduit for carrying water from a roof drainage component to ground level.
Drip Edge:
A metal flashing bent at a 90º angle that is installed along the roof edge.

Dry Rot:
Wood rot caused by certain fungi.

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Eave: A roof edge that extends out past the exterior wall line.

A gutter.

Eave Starter:
A starter strip placed along eave edges to start the course(row).

Edge Stripping: 
Roofing material used to seal perimeter edge metal and the roof membrane.
Eave Venting: 
The installation of vent material or components along a roof edge as part of a ventilation system.

End Lap:
Generally refers to the point at which the end of one roll of roofing felt or membrane overlaps the end of the adjacent roll.

(1) The physical components of a building that form a barrier between the indoor and outdoor environments (2) A continuous seal for preventing bitumen from leaking down into or off a building.

Expansion Cleat:
A cleat designed to handle thermal movement of the metal roof panels.

Expansion Joint:
A built-in separation between building sections to allow for free movement between the sections without damaging the buildings structural components.

(1) The portion of the membrane that is not overlapped by the succeeding ply or course. (2) The portion of the roofing material exposed to the weather after being installed.

Exterior Wall Line:
The point where the exterior walls meet the roof.

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

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Factory Seam:
A splice/seam made in the roofing material during the manufacturing process.

Losing brightness or brilliance.

Vertical roof trim located along the perimeter of a building usually below the roof level.

Fascia Board:
A board attached to the ends of the rafters between the roofing material and the soffit overhang.

Devices, such as screws or nails, used to mechanically secure roof system components.

Feathering Strips:
Strips of wood that are placed along the butt ends of wood shingles to form a relatively smooth surface so that the shingles can be roofed over without removal.

A roofing sheet.

Fiberglass Insulation:
Insulation composed of glass fibers used to insulate walls and roofs.

Field of the Roof:
Refers to the main roof area excluding flashings.

Field Seam:
A non-factory material seam made by joining overlapping seams together.

A sharp protrusion in a roof deck that can damage roof components.

Fine Mineral-Surfacing:
A fine mineral material on the surface of roofing materials to prevent them from sticking to surfaces.

(1) A half-cylindrical or half-conical opening (resembling a fishes mouth) formed in roofing felts by an edge wrinkle; (2) In shingles, a half-conical opening formed at a cut edge.

Flame Retardant:
A substance used to impede a material’s tendency to burn or ignite.

The ability of a material to burn or ignite.

A projected edge at the base of a roof flashing component such as flashings. to secure and seal the component to the roof membrane.

Components used to seal the roof system at areas where the field membrane intersects vertical surfaces or is otherwise interrupted by adjoining walls, curbs, roof drains or pipe penetrations.

Flashing Collar:  
A flashing component used to seal pipe penetrations.
Flat Lock:
A type seam formed at the intersection of two adjacent metal sheets by folding one edge over on top of itself and the folding the other down under itself and then locking the panels together.

Framed Opening: 
A structurally-framed opening in a roof deck, formed to facilitate the installation of large items such as HVAC units, skylights, or ventilators.

The total of the structural roof members which when connected form the support for the roof coverings.

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A triangular-shaped portion of the end wall of a building formed by the sloping roof and above the eave line.

Gable Roof:
A roof configuration in which two planes slope so as to form a triangle.

Trade name for a protective coating composed of aluminum zinc.

Galvanized Steel:
Steel that is coated with zinc to aid in corrosion resistance.

A roof that has two different pitches.

A standard of measurement.

A small aggregate, naturally or synthetically colored, used to surface cap sheets, shingles, and other granule-surfaced roof coverings.

Gravel Stop: 
A flanged, sheet metal edge flashing with an upward projection installed along the perimeter of a roof to prevent the migration of gravel or bitumen over the roof edge.

A channel installed along the low perimeter of a roof to convey runoff water from the roof to the rain water leaders or downspouts.

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Hatch: A unit used to provide access to a roof from the interior of a building.

The minimum distance, measured at 90 degrees to the eaves along the face of a shingle or felt, from the upper edge of the shingle or felt to the nearest exposed surface.

The edge created by folding metal back on itself.

The line where two adjacent sloping sides of a roof meet.

Hip Roof:
A roof that rises by inclined planes on all sides of a building.

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Ice Dam:
Ice formed at the transition from a warm surface to a cold surface.

Impact Resistance:
A roof assembly’s ability to withstand the impact from falling objects.

Roof slope.

Material used to help maintain a certain temperature in a building by reducing the flow of heat to and from that building.

Intake Ventilation:
The part of a ventilation system used to draw fresh air in.

Interlocking Shingles:
Shingles that lock together to provide wind resistance.

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Edging used for the transition between existing roof edge and steel.

Joint Tape: Tape used to seal joints between insulation boards.

Any of the parallel horizontal beams set from wall to wall to support the boards of a floor, ceiling or roof of a building.

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A groove or a notch made by a cutting tool.

Knee Cap: Sheet metal trim that fits over a panel rib after it has been cut and bent.

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The area where adjacent roof components overlap each other.

Lap Seam:
Where two material that overlap are sealed together.

Leader Head:
A component used to direct water from a gutter to a downspout.

Leader Pipe:
A conduit for carrying water from a gutter, scupper, drop outlet or other drainage unit from roof to ground level.

Live Loads:
Temporary items on a roof such as equipment, people, snow, etc., which the roof must be designed to support.

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(1) A steep-sloped roof section located at the perimeter of a building and usually used for decorative purposes. (2) The upper story formed by the lower slope of a mansard roof.

Mansard Roof:
A steeper roof that terminates into a lower sloped roof at its high point.

A thin layer of woven, non-woven, or knitted fiber used to reinforce a material.

Mechanical Damage:
Damage to a roof by means of items puncturing or otherwise unnecessarily penetrating the roof system.

Mechanical Fasteners:
Devices such as screws, plates, battens, nails, or other materials that are used to secure roofing materials.

The portion of the roofing system that serves as the waterproofing material.

Metal brake:
A machine that will fold, bend or flange metal.

Metal Flashing:
Roof components made from sheet metal that are used to terminate the roof membrane or material along roof edges and at roof penetrations.

A superficial coating or discoloration of organic materials caused by fungi especially under damp conditions.

The joint made by two diagonally cut pieces put together.

Moisture Relief Vent:
A vent installed through the roofing membrane to relieve moisture vapor pressure that has been trapped within the roofing system.

Mud Cracking:  
Surface cracking of a material that looks similar to dried, cracked mud.

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A piece of lumber that is secured to the roof deck, walls or to curbs.

Nailing Pattern:
The pattern used to nail a roof components in place.

To overlay existing shingles with new shingles and butt the top edge of the new shingle up against the bottom edge of the existing shingles.

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Open Valley:
A valley where both sides of the roof are trimmed back from the centerline to expose the valley flashing material beneath.

Oriented Strand Board

The part of the roof that hangs out or over the outside wall.

The installation of a new roof system over an existing system without removing the existing system.

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(1) The concave piece of "Pan and Cover" tile whose rounded surface touches the top side of the roof substrate. (2) The flat part of a roofing panel located between the ribs.

Pan Flashing:
A sheet metal flashing that covers an equipment platform and is designed to counter flash the base flashings surrounding the platform.

Parapet Wall:
That part of a perimeter wall that extends above the roof elevation.

An object that penetrates the roof structure such as a plumbing vent pipe or electrical conduit.

A small hole in a coating, foil, membrane or other roofing material.

Pipe Boot:
A prefabricated flashing component used to flash around pipe penetrations.

Term used to describe Roof Slope.

Pitch Pocket: 
A flanged piece of flashing material placed around irregularly shaped roof penetrations and filled with a sealing material to create a watertight seal around the penetration.
Pitched Roof:
A steep roof.

A puddle of water that does not drain off of a roof membrane.

Positive Drainage: 
A roof surface that slopes toward the drainage components in order to ensure complete drainage of the roof area.

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R-Value: The measure of a material’s resistance to heat flow.

The structural member which extends from the roof eave to the ridge or hip and is designed to support the roof deck and roof system components.

The sloped perimeter edge of a roof that runs from the eaves to the ridge. The rake typically runs perpendicular to the eaves and ridge.

A starter strip placed along rake edges for use roofing.
The installation of a new roof system over an existing system without removing the existing system.

A groove in a wall or other surface adjoining a roof surface for use in the attachment of a counterflashing.

The procedure of installing a new roof system.

The line where two planes of a roof intersect at their highest edges.

Ridge Cap:
Material applied over the ridge or hip of a roof to create a watertight installation.

Ridge Vent:
An exhaust venting device located at the ridge of a roof that works in conjunction with a starter or under eave soffit vent and is used to ventilate attics.

An upward tenting displacement of a roof membrane frequently occurring over insulation joints, deck joints and base sheet edges.

Roof Assembly:
A term used to describe all of the roof components including structural roof deck, insulation, membrane and flashings.

Roof Curb: 
A raised frame used to structurally mount and waterproof rooftop equipment such as HVAC units, exhaust fans, roof hatches or skylights.

Roof Decking:
Lumber installed on a roof system.

An individual who installs roof systems and materials.

Roof Jack:  
A steel bracket fastened to the roof that is used to support toe boards.

Roof Overhang:
The portion of the roof that extends beyond the exterior wall line of the building.

Roof Seamer:
(1) A mechanical device used to crimp metal roof panels and make the seams watertight. (2) A machine used to weld membrane laps of PVC or other thermoplastic roof membranes.

Roof Slope: 
The angle formed by the roof surface plane with the horizontal plane of the building expressed as the amount of vertical rise for every twelve inches of horizontal run.

Roof System:
Multiple roof components assembled to provide waterproofing (and sometimes insulating) capabilities for a structure.
Run: The horizontal dimension of a slope.

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A small structure designed to facilitate drainage of water away from flashing components.

Settling or drooping of base flashings that have not been properly secured to a surface.

Generic term for amaterials used to seal joints or junctures against moisture or weather.

A line, ridge, or groove formed from fitting, joining, or lapping two components.

Self-Tapping Screws:
A screw with a small drill-bit like tip that will drill its own hole and eliminate the need to pre-drill a hole.

A single piece of prepared roofing material textured to mimic a wood split appearance.

Shark Fin:
A curled corner or lap in a membrane.

The boards or sheet material fastened to the roof rafters on which the shingle or other roof covering is laid.

Shed Roof:
A roof with only one sloping plane.

A single piece of prepared roofing material roofing material usually with a smooth texture for use in steep slope roof systems.

Shingle clips:
A device for holding a shingle in place.

Shingle Fashion:
The overlapping of succeeding courses of roofing materials.

Side Lap:
The longitudinal overlap of adjoining materials.

Exterior wall finish materials applied to the outside of a structure.

The bottom framing member of a door or window opening.

Sill Flashing:
Flashing material(s) used to waterproof the bottom framing member of a door or window opening.

A transparent or translucent item that is designed to admit light to the interior of the structure.

A fine-grained metamorphic rock that splits into thin, smooth-surfaced layers used in steep slope roofing applications.

Slip Sheet:
Sheeting material placed between roofing components to prevent those components from adhering to one another or to prevent material damage due to component incompatibility.

The angle of incline of a roof expressed as a percent or as a ratio of rise to run.

Snow Guard:
Devices secured to the roof to prevent snow and ice from sliding off the roof’s surface.

Snow Load:
A roof load resulting from snow accumulation.

The underside of a roof overhang.

Soffit Vent:
An intake ventilation device located in the soffit.

Soil Pipe:
A pipe that penetrates a roof and is used to vent a building’s plumbing.

Splash Guard:
A fabricated metal pan or masonry block that is placed below a leader pipe or downspout and is used to help protect the roof membrane on a lower roof level.

To join along ends.

Splice Plate:
A metal plate placed above or below the joint between two adjacent pieces of metal.

Splice Tape:
A self-adhering tape used for splicing membrane materials.
The separation of a material resulting from tensile forces.

Sprayed Polyurethane Foam (SPF):
A monolithic sprayed-on roofing material with a high R-value.

(1) 100 square feet of roof area (9.29 m2) in the USA. (2) 10 square meters (107.639 ft.2) of roof area using the metric system of weights and measures.

Stair Step:
The diagonal method of laying shingles.

Standing Seam:
A type of metal roof system where the longitudinal seams on adjacent panels are turned up, overlapped and folded in various ways in order to prevent moisture entry and interlock the panels.

Starter Strip:
Strips of shingles or roll roofing material that is laid along the eave line of the roof prior to the application of the first course of shingles. The starter strip is used to fill in the gaps created by shingle cutouts and joints.

Static Load:
Roof loads that do not move such as HVAC units.
Steep-Slope Roof:
A roof with a slope exceeding 3 in 12 (25%) deemed appropriate to receive water-shedding type roofing materials.

Steep-Slope Roofing Materials:
Roofing materials that depend on their water-shedding capabilities to keep moisture from entering a building.

Step Flashing:
Pieces of metal or other material that are used to flash roof projections such as chimneys, walls, curbs, etc. The pieces are installed between each course of roofing and generally have a vertical flange equal in length to that of the horizontal flange.

Installing roofing felts so that they run parallel with the slope.

Strip Flashing:
Pieces of membrane material that are used to flash metal flashing flanges.

Sub Seal:
Sheet type water proofing membrane.

The surface upon which the roofing is installed.
Surface Erosion:
The effect on a surface after being worn away from abrasion or weathering.

The top-most layer of the roof system designed to protect the system from damage.

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Tapered Edge Strip:
Tapered insulation strip used to ease transitions from one substrate elevation to another and to provide slope along roof perimeters.

To remove a roof system down to the structural substrate.

Tensile Strength:
The amount of longitudinal pulling stress that a material can withstand before being pulled apart.

The sealed edges of a roof membrane.

Termination Bar:
A bar used to seal and anchor the free edges of a roof membrane.

Terra Cotta: 
Fired ceramic clay used in building construction.

Thermal Insulation:
A material used to reduce heat flow.

Thermal Movement:
Movement of a material resulting from temperature changes.

Thermal Resistance (R):
The measure of a material’s ability to resist heat flow.

Thermal Shock: 
The stresses imposed by expansion and contraction which are the result of sudden extreme temperature changes.

Thermal Stress:
Stress to a roof system or component caused by expansion and / or contraction from temperature change.

(1) The cutout of a shingle. (2) The narrowing passage located between a fireplace and smoke chamber or flue.

Through-Wall Flashing:
A material that extends through a wall and is used to direct water entering a wall cavity to the exterior of the structure.

The joining of two different roof systems.

Toggle Bolt:
A bolt with a separate toggle end that can be flattened to fit through a pre-drilled hole and that springs outward to provide strength when the bolt is tightened.
Force applied to an object, particularly, to screw a mechanical fastener into a roof deck or substrate.

Transverse Seam:
The joint between the top of one metal roof panel and the bottom of the next panel, which runs perpendicular to the roof slope.

Trim Coil:
Soffit and fascia finishing trim.

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The overall coefficient of heat transfer of an assembly measured in BTUs per square foot, per degrees Fahrenheit difference in temperature per hour.

A material installed over the roof deck prior to the application of the primary roof covering.

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The internal intersection of two sloping roof planes that runs from the eaves to the ridge.

Valley Cap:
A lead cap overlaid  onto each valley.

Vapor Retarder: A material used to restrict the passage of water vapor through a roof assembly.

An opening or device used to permit air or vapors to exit an enclosed structure.

A device that circulates fresh air and expels stale air.

Having a fairly high resistance to heat flow.

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Waterproof: Being resistant to moisture infiltration.

The treatment of a surface or structure in order to prevent the passage of water.

To undergo degradation in quality and appearance which is caused by exposure to the elements.

Weep Holes:
Small holes used to permit moisture to drain that has gathered inside a building component.

Wind Clip:
A clip that slips over the ends of tile, slate and other steep slope roofing materials in order to help prevent wind uplift damage.

Wind Load:
The force that wind puts on structures.

Wind Uplift:
(1) The upward displacement of a section of a roof system or component caused by movement of air from a location of higher air pressure, such as inside a building, to an area of lower air pressure, such as the surface of a roof during a windy day.

Woven Valley:
A valley construction whereby the valley has a woven look which is effected by overlapping alternate courses of shingles from both sides of the valley.

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