Two additional Watertite Roofing team members have now successfully completed The Roofing Technology, Maintenance and Inspection course.
Understanding terminology used in the flat roofing industry, can better equip you when considering a flat roofing system or metal retrofit replacement. Below is an extensive list of roofing terms to help:
Alligatoring - Crackling in roofing products due to shrinkage from sunlight, oxidation or heat/cold exposure.
Asphalt – Dark substance, petroleum based byproduct of processing crude oil to obtain fuels.
Base Sheet - A heavy sheet often used as the first ply in built-up roofing.
Base Flashing - Attached or rests on roof deck and directs water flow or seals against the deck. May also be material applied to wall base extending above a roof, as protection for the junction of the wall, and the roof.
Bitumen - Bitumens are mixtures of hydrocarbons. In roofing terms this covers both asphalt and coal tar pitch.
Blisters - Air, water vapor or other gases trapped within the plies of the roofing causing bubbles upon the roof surface.
Bond - Adherence between elements of the roof system.
Breather - A roof vent penetrating the roofing membrane to allow escape of moisture and air from insulation.
Buckling - Warping or wrinkling of a roof membrane.
Built-up Roofing - Layers of roofing felt bonded together on site, usually has a protective surface coating of gravel often in a heavy top coating of bitumen.
Cant Strip - A support used at the intersection of the roof deck, used in built-up roofing but not required in single ply roofing.
Cap Flashing - Portion of flashing built into a vertical surface to prevent the flow of water behind the base flashing. The cap flashing overlaps and caps off the top of the base flashing.
Caulking – Adhesive which fills in gaps and joints.
Coal Tar Pitch - Bituminous material distilled from crude tar derived from coal. Formerly used as the waterproofing material for tar and gravel built-up roofing. Now a “designated substance” and carcinogen--obsolete and undesirable in modern roofing practice.
Concealed Fasteners or Nails - A technique used in roll roofing that conceals or covers all fasteners or nails used to secure roofing materials to decking.
Condensation - Change from water vapor to liquid water, resulting from a drop in temperature of an air vapor mixture..
Cracking - A fissure or fissure pattern appearing on asphalt roofing material due to weathering exposure.
Curb - Wall of concrete, wood or masonry built above the level of the roof, surrounding a roof opening such as for installation of hvac units.
Dead Load - Total weight of installed materials along with the continual weight of a roof--such as snow or water, and used to calculate the strength of the supporting frame.
Deck - Top building surface over which a roof system is applied.
Downspout - Pipe conveying water from roof gutters to a drain.
Drip Edge - L-shaped flashing used at eaves to direct runoff water into gutters away from the fascia.
Eave - Horizontal roof overhang that is not directly over the exterior walls or the buildings interior.
Expansion Joint - Controlled joint between two sections of a roof and allows building envelope to expand and contract without causing harm to the roof.
Exposure - Subjected to the elements of weather.
Fascia - Vertical face trim board used to hide the ends of rafters and sheathing.
Fastening Tab - Part of Duro-Last roofing system where membrane is mechanically attached to the deck.
Felts - Mat of organic or inorganic fibers used with tar and gravel roof systems.
Fire Wall - Built for the purpose of restricting the spread of fire in a building.
Fire-Resistant - Material that is resists ignition.
Flashing - Treatment of the edge of a roof with metal usually galvanized colour coated sheet metal - may also be copper, tin or aluminum.
Gutter – A valley which conveys water from the roof to downspout.
Header - The beam into which joists are fitted when framing around a roof opening.
Heat Welding - Hot air process where two pieces of material are bonded or fused together.
Live Load - Total weight of all installed equipment and materials along with the various weights that will move across a surface. A maintenance crew working on the roof would be part of a live load and HVAC equipment vibrations also--any impact load moving on or across a roof.
Membrane - The skin of waterproofing system or roof covering which protects the interior functions of a building.
Overhang - A portion of roofing extending beyond the deck such as the part of the roof structure which extends beyond the exterior walls of a building.
Parapet - Low wall along the edge of a roof deck, generally an extension of exterior building walls and above firewalls that extend above the roof.
Pitch - Height from the joist to ridge divided by rafter length, translates to rise in inches per horizontal foot or ratio. This creates the angle of a roof.
Pitch Pan - A rectangular or circular metal collar placed around supports that protrude above a roof deck. The pitch pan is placed on top of the roofing underlayment.
Plastic Cement - A mixture of asphalt, solvent and mineral stabilizer used to adhere or fill flashings.
Ply - Thickness of roofing material. Roofs are described according to the number of layers used to build up the membrane.
Ponding - Collection of water in pools on the roof top.
Primer - Thin coating used on asphalt, concrete or metal in preparation of applying a built-up roof.
Rolled Roofing - Roofing material, which comes from the manufacturer in rolls.
Roof Drain – Fitting of an interior drain and leader for draining water from flat roofs.
Roof Insulation - Material used as part of the roofing system to reduce heat loss.
Roofing System - Waterproof roof membrane, roof insulation, vapor barrier and roof deck as an entity.
Scrim - Component of the Duro-Last membrane. A weft sandwiched into the PVC and creating a grid-like appearance. If the Duro-Last membrane is ever punctured this scrim prevents further damage.
Scupper - Outlet in the wall of a building or a parapet wall for drainage of overflow
Sky Light - Glass or plastic insertion in roof for the admission of light.
Thermoplastic - Type of membrane that can be heat welded and includes a re-inforcement layer of polyester (scrim) in the weft.
Titanium Dioxide - Used in thermo-plastic roofing membranes to reflect UV rays and to protect the polymers in the roofing material.
Truss - A combination of components like beams, bars and ties, arranged to form a supporting framework for loads over spans of roof construction.
Valley - Horizontal line formed at the bottom of two inclined roof surfaces.
Vapor Barrier or Vapor Retardant - Material that prevents the passage of water vapor through it.
Vent - Outlet for air, a ventilating duct.
Vent Pipe - Vertical pipe providing an escape for foul gasses.
Vent Stack - A large vertical pipe leading to the outside through the roof.
Walk Pads - A reinforced product, layed out on the roof surface in a pathway configuration. Designed for the safety and protection of the roof membrane from damages due to human activity upon the building.
Water Vapor - Moisture as a gas in air.
Wrinkle - A slight ridge caused by folding or creasing. Refers to the common crinkle pattern that forms over the joints or insulation in roofing.