C,D,

Dictionary of Roofing Terms

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Calender: A machine used to laminate sheeting or for applying coating with a specified thickness and/or surface attribute.

Calendering: A specific process used to manufacture some membranes such as PVC.

Camber: A slight convex curve of a surface.

Canopy: An overhang, usually over entrances or driveways.

Cant: (1) Short for Cant Strip; (2) The act of installing foam at a right angle adjunct.

Cant Strip: A triangular-shaped strip of material used to ease the transition from a horizontal plane to a vertical plane. Cant strips can be made of wood, wood fibre, perlite, or other materials.

Cap Flashing: A material used to cover the top edge of base flashings or other flashings. (See also Coping.)

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

Capacitance Meter: A device for locating moisture within a roof system by measuring the ratio of the change to the potential difference between two conducting elements that are separated by a non-conductor.

Catalyst: A substance that effects a chemical reaction and/or the rate at which a chemical reaction takes place. In roofing, catalysts are used in fibreglass roofing.

Cathodic: metals low in the Galvanic Series.

Caulk: A material with no elastomeric properties used for sealing joints.

Caulking: The act of sealing a joint or of material.

CCF: 100 cubic feet.

C-Channel: A structural framing member that, when viewed cross-sectionally, has the shape of a "C".

Cellulose: A complex carbohydrate, (C6H10O5)n, that is composed of glucose units, forms the main constituent of the cell wall in most plants, and is used in the manufacturing of organic roofing materials.

Cellulose Insulation: Ground up newspaper that is treated with a fire retardant.

Certification: A written declaration that a particular product or service complies with stated
criteria. In specific use, it is necessary to include the scope and limitations of the certifications;
usually it is provided by the manufacturer, producer or vendor.

Chalk: A powdery residue on the surface of a material.

Chalking: A process by which finishes develop a loose powdery surface resulting from
decomposition of the binder, principally through the action of ultraviolet rays.

Chalk Line: (1) A string on a reel in a container that can hold chalk; (2) A line made on by pulling taut a string coated with chalk and snapping it.

Channel Flashing: Flashing with a built-in channel for runoff; used where roof planes intersect other vertical planes.

Chemical Resistance: A materials ability to retain its properties when it comes into contact with certain chemicals.

Chlorinated Polyethylene¹ (CPE): CPE is a flexible material with high tear strength, good chemical resistance and patency towards UV radiation. As a result of the high chlorine content (typically 30%) it is inherently difficult to ignite, but releases hydrogen chloride during combustion. It suffers from an extremely high permeability to gas. Resistance to most inorganic chemicals is generally good, while resistance to hydrocarbons increases with increasing chorine content. The material is used mainly as an impact modifier for PVC and, to a lesser extent, LDPE and HDPE film.

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

Cleat: A continuous metal strip used to secure two or more metal roof components together. Commonly used along with coping or gravel stop on tall buildings.

Clip: A small fastening device, usually of metal, designed to hold a panel or component in place.

Clipped Gable: A gable cut back at the ridge in a small hip configuration.

Closed-Cut Valley: A method of valley application 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 approximately 2 inches from the valley centreline.

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

Coal Tar Bitumen: A proprietary trade name for Type III coal tar used in dead-level or low-slope built-up roofs. It is not for use in roofs exceeding ¼" in 12" (2%) slope.

Coarse Orange Peel Surface Texture: A surface showing a texture where nodules and valleys are approximately the same size and shape. This surface is generally acceptable for installing a protective coating.

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

Cohesion: Mutual attraction by which the elements or particles of a body or substance are held together.

Cold Applied: Products that can be applied without heating. These are in contrast to products which need to be heated to be applied.

Cold Patch: A repair done with cold applied material.

Collar Beam: A tie that stops a pitch roof from spreading, connects similar rafters on opposite sides of the roof.

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

Combing Ridge: A term used to describe an installation of finishing slate at the ridge of a roof whereby the slates on one side project beyond to the apex of the ridge.

Combustible: Capable of igniting and burning.

Compatible: Two or more substances which can be mixed or blended without separating, reacting, or affecting either material adversely

Condensate: The liquid resulting from condensation.

Condensation: The conversion of water vapour to liquid state when warm air comes in contact with a cold surface. (See also Dew Point.)

Conduction: The transmission or conveying of something through a medium or passage, especially the transmission of electric charge or heat through a conducting medium without perceptible motion of the medium itself.

Construction Joint: A constructed joint where two successive instalments of concrete come together.

Contact Cements: Adhesives used to adhere or bond roofing components.

Convection: Transfer of heat by movement of heated molecules.

Coping: the piece of material used to cover the top of a wall and protect it from the elements. It can be constructed from metal, masonry, or stone.

Copper: A reddish-brown element that conducts heat and electricity very well. It is also used as a primary roof material as well as a flashing component. Copper turns a greenish colour after being exposed to the weather for a length of time and appears in the middle of the Galvanic Series.

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

Corrugated: Folded or shaped into parallel ridges or furrows so as to form a symmetrical wavy surface.

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

Counterflashing: Formed metal sheeting secured to walls, curbs, or other surfaces, for use in protecting the top edge of base flashings from exposure to weather.

Cove: In roofing, a heavy bead of sealant material installed at the point where vertical and horizontal planes meet. It is used to eliminate the 90° angle. See also Fillet.

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

Coverage: The surface area covered by a material.

Crack: A separation or fracture occurring in a material. See also Split.

Crazing: A series of hairline cracks in the surface of a weathered material, having a web like appearance.

Creep: Movement of roof membrane causing the roof system to be deformed

Cricket: A roof component used to divert water away from curbs, platforms, chimneys, walls, or other roof penetrations and projections. See also Saddle.

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

Curb: (1) A raised member used to support skylights, HVAC units, exhaust fans, hatches or other pieces of mechanical equipment above the level of the roof surface, should be a minimum of eight inches (8") in height; (2) A raised roof perimeter that is relatively low in height.

Cure: A process by which a material is forms permanent molecular linkages by exposure to chemicals, heat, pressure, and/or weathering.

Cure Time: The time necessary to effect curing.

Curing Agent: A material additive that alters chemical activity between the components resulting in a change in the rate of cure.

Curing Compound: A liquid that is applied to newly installed concrete which slows water loss while curing.

Damp proofing: Treatment of a surface or structure to resist the passage of water in the absence of hydrostatic pressure.

Dead Level: Refers to a roof with no slope or pitch.

Dead Loads: Permanent, non-moving loads on a roof resulting from the weight of a building’s components, equipment, and the roof system.

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

Decking: See Deck.

Deflection: The downward displacement of a structural member under load.

Degradation: A decline in the appearance, structure, or properties, of a material or substance.

Delamination: Separation of laminated layers of a material or system.

Dew Point Temperature: The temperature at which water vapour turns to liquid in cooling air at the existing atmospheric pressure and vapour content.

Diaphragm: A type of structural roof deck capable of resisting shear that is produced by lateral forces such as wind or seismic loads.

Diffusion: The movement of a substance such as water vapour from regions of high concentration to regions of lower concentration

Dimensional Stability: The ability of a material to retain its current properties and to resist a change in size resulting from exposure to temperature changes and moisture.

Dome: A roof with a partial-spherical shape.

Dormer: A framed projection through the sloping plane of a roof. (See Fig1 )

Double Coverage: Installing roofing so that there are twice the materials used resulting in a double layer of roofing.

Downpipe: A conduit for carrying water from a gutter, scupper, drop outlet or other drainage unit from roof to ground level. Also known as a Leader Pipe. (See Fig 1)

Downspout: See Downpipe. (See Fig 1)

Drain: a device used to carry water off of a roof.

Drawing: an architectural, structural, mechanical or electrical plan, elevation or section indicating
in isometric or in axonometric perspective, the detailed location, dimension, quantity or extent of
material, product or member to be furnished.

Drawing outline: A top view drawing of a building or roof showing the roof perimeter drawn to scale.

Drip Edge: A device designed to stop water running back under an overhang. A fibreglass (or steel) flashing formed at a 90º angle that is placed along the outer perimeter of steep sloped buildings; used to help direct runoff water away from the building. Drip Edge resembles nosing except that it has an outwardly angled bottom edge (preferably hemmed). To see the difference between Drip Edge and Nosing, See Nosing.

Dry Rot: Wood rot caused by certain fungi. Dry rot can result from condensation build-up, roof leaks that go untended, or from other problems. Dry rot will not remain localized. It can spread and damage any lumber touching the affected area.

Dual Level Drain: An item that will permit drainage at two different levels.

Dynamic Load: Any moving load on a roof such as people and equipment. Wind can also be considered a Dynamic Load.

Although these pages are checked regularly and every care is taken with the information within. Delston can not accept any responsibility or liability for information or results displayed within due to third party interference.

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