Roofing Terminology

Understanding the terminology used in the roofing industry can be incredibly beneficial, especially when you’re considering a roof repair or replacement. This comprehensive guide aims to demystify the jargon, providing you with the knowledge you need to confidently discuss your roofing needs with a contractor.

• Apex: The apex refers to the highest point of the roof, where the two slopes meet at the ridge.
• Apron Flashing: This is a one-piece flashing used at the lower side of a chimney that penetrates a sloping roof.
• Barge Board: The barge board covers the roof timbers on the gable or skillion end of a roof. It is fixed parallel to the roof slope.
• Batten: A batten is a piece of timber or metal channel installed horizontally on top of the rafters. It allows sheet metal to be laid and fastened.
• Base Metal Thickness (BMT): BMT describes the thickness of the metal used, not including coatings or paint.
• Bay Window: A bay window is a window of varying shapes, projecting outward from the wall of a building, forming a recess in a room.
• Box Gutter: This is an internal concealed roof gutter between the slopes of a roof or a roof and a wall. It discharges water internally through a sump.
• Canopy: A canopy is any overhanging or projecting roof structure, typically over entrances or doors.
• Capping: Capping is a covering fixed to the top of a parapet wall or the edge of roofing, forming a waterproof seal.
• Ceiling Joists: These are the horizontal members that provide a structure to fix the ceiling. They support and fix the diagonal rafters that define the roof shape and are attached at the top to a ridge beam.
• Cladding: Cladding is any material used to face a building or structure, otherwise known as wall cladding.
• COLORBOND®: COLORBOND® steel is produced with a ZINCALUME® base to provide corrosion resistance. It is then covered with a chemically applied conversion layer to enhance coating adhesion. On top of this goes a baked-on epoxy primer and finally a baked-on exterior grade top-coat.
• Contractor: A contractor is one who agrees by written agreement or contract to supply materials and perform certain types of work for a specified sum of money.
• Cricket: A cricket, or saddle, is a peaked construction that ensures water flow away from chimneys or other roof projections.
• Cupola: A cupola is a relatively small roofed structure generally set on the ridge or peak of a main roof area.
• Deck: The deck is the structural substrate of a roof and is usually made of wood or concrete.
• Dormer Window: A dormer window is a vertical window or opening, coming through a sloping roof and usually provided with its own pitched roof. It is often used in attics to add light and a pleasing design to the house.
• Downpipe: A downpipe is a pipe for draining water from the rainwater gutters to the ground or storm water runoff system.
• Drip Edge: A drip edge is a metal flashing or other overhanging component with an outward projecting lower edge, intended to control the direction of dripping water and help protect underlying building components.
• Eave Vent: An eave vent is a vent that allows air to flow into the attic. It’s typically installed in the soffit area beneath the eaves.
• Eaves: The eaves are the lower part of a roof that overhangs the walls.
• Eaves Flashing: Eaves flashing is an additional layer of roofing material applied at the eaves to help prevent damage from water backup.
• Fall: The fall refers to the slope or pitch of a roof or gutter.
• Fascia: A fascia is a board fixed horizontally to the lower ends of the rafters, to which guttering is fixed.
• Fasteners: Fasteners are any of a wide variety of mechanical securement devices and assemblies, including nails, screws, cleats, clips, and bolts. They may be used to secure various components of a roof assembly.
• Felt: Felt is a flexible sheet manufactured by the interlocking of fibers with the use of heat, moisture, and pressure. Roofing felts are often made of organic or fiberglass substrate, saturated with asphalt.
• Finial: A finial is usually a pointed ornament at the top of a gable, hip junctions, and dutch gables.
• Fire Rating: The fire rating is a system for classifying the fire resistance of various materials. Roof materials are rated Class A, B, or C, with Class A materials having the highest resistance to fire originating outside the structure.
• Flashing: Flashing is used to weatherproof or seal the roof system edges at the perimeters, penetrations, walls, and other places, such as vent-pipes, chimneys, valleys, and joints at vertical walls.
• Gable: The gable is the triangular end of a house formed at the end of a pitched roof, from eaves level to apex.
• Gutter: A gutter is a channel (usually sheet metal) installed along the down slope perimeter of a roof to convey runoff water from the roof to the downpipes.
• Gutter Guard: A gutter guard is a purpose-made perforated system installed over the gutter to prevent gutters clogging from leaves and other debris.
• Hip: The hip is the inclined external angle formed by the intersection of two sloping roofs. The hip runs from the ridge to the eaves.
• Hipped Roof: A hipped roof has an end roughly pyramidal in shape, with surfaces sloping upwards from all three eaves.
• Ice Dam: An ice dam is a condition of snow and ice build-up on the roof, which can force water under the shingles and leak into the house.
• Insulation: Insulation, or more correctly thermal insulation, is a general term used to describe products that reduce heat loss or heat gain by providing a barrier between areas that are significantly different in temperature.
• Joist: A joist is a horizontal structural member used in framing to span an open space, often between beams that subsequently transfer loads to vertical members.
• Lead Flashing: Lead flashing is a soft workable metal used for sealing roof penetrations.
• Louvers: Louvers are slatted devices installed in a gable or soffit (the underside of eaves) to ventilate the space below a roof deck and equalize air temperature and moisture.
• Parapet Wall: A parapet wall is a perimeter wall which extends above the roof.
• Penetration: Penetration refers to any object that passes through the roof.
• Ponding: Ponding refers to the accumulation of water at low lying areas on a roof.
• Profile: The profile refers to the shape and design of the materials.
• Purlins: Purlins run horizontally and parallel to the ridge beam and perpendicular to the roof slope. They are fixed on top of the rafters and help prevent roof sag.
• Rafter: A rafter is a parallel beam thatsupports the roof and is part of the truss. It is the principal support for roofing materials.
• Rainwater Head: Rainwater heads are an essential design element for buildings where internal box gutters are used. A rainwater head or sump is a container located between the gutter and downpipe that aids the flow of water away from the roof. It acts as an external overflow point to minimise water surges into the storm water system and aid the flow of water down the downpipe.
• Ridge: The ridge is the highest point on the roof, represented by a horizontal line where two roof areas intersect, running the length of the area.
• Ridge Capping: Ridge capping is a covering over a ridge line forming the waterproof seal between the two sides of the roof.
• Roof Pitch: The roof pitch is the angle formed between a sloping roof surface and a horizontal line, usually expressed in degrees.
• Roof Span: The roof span is the distance across the roof and measured to the outer edges of the wall plates.
• Roof System: A roof system is a system of interacting roof components designated to weatherproof and to insulate a building top surface.
• Roof Truss: A roof truss is a frame designed to carry the loads of a roof and its covering over the full span without intermediate support.
• Sarking: Sarking is a strong, moisture-proof, reflective, metallic building paper which is placed over the roof battens/purlins and installed beneath the external roof covering. It is ideal for waterproofing and insulation.
• Scaffolding: Scaffolding is a temporary structure specifically erected to support access platforms or working platforms.
• Scribing: Scribing involves cutting a piece of sheet metal to fit the profile of another to which it is to be fitted.
• Sealant: A sealant is a mixture of polymers, fillers, and pigments used to fill and seal joints where moderate movement is expected. It cures to a resilient solid.
• Sheathing: Sheathing is the board or panel material used in floor, wall, and roof assemblies of both residential and commercial construction. The most basic function of sheathing, in any application, is to form a surface onto which other materials can be applied.
• Skillion: A skillion is a roof shape consisting of a single sloping surface.
• Skylight: A skylight is a glazed window or translucent roof section fitted parallel to the roof slope to admit light.
• Soffit: The soffit is the lining installed under the eaves between the fascia board and external wall.
• Sump: A sump is usually attached between a box gutter and the downpipe. They collect storm-water before it is carried away by the downpipe and they also serve to catch any debris before it enters the downpipe.
• Total Coating Thickness (TCT): TCT is a term used to describe the overall thickness of a colored or coated sheet metal. This figure includes the Base Metal Thickness, plus the paints or coatings.
• Truss Roof: The truss roof is the prefabricated, self-supporting, triangulated structural framework commonly used for all types of roofs.
• Underlayment: Underlayment is a layer of asphalt-saturated felt (often called tar paper) or a synthetic fabric that’s installed on the deck before the roof covering. It provides additional protection for the deck and forms a secondary weatherproofing barrier.
• Valley: The valley is the internal angle formed by two inclined slopes of a roof. A metal ‘V’ shaped gutter is fixed in this area to direct water to the gutter.
• Vapour Barrier: A vapour barrier is a material designed to restrict the passage of water vapor through a roof system or wall.
• Vent: A vent is an opening or device used to permit air or vapor to exit an enclosed structure.
• Waterproofing: Waterproofing is the treatment of a surface or structure to prevent the passage of water under hydrostatic pressure.
• Wind Uplift: Wind uplift is the suction effect that wind can have on a roof. It can cause a roof to be lifted and removed from a building during a windstorm.
• Whirly Bird: Whirly birds are a type of semi-mechanical vent that can be installed on the roof to help remove heat from the ceiling cavity.
• ZINCALUME®: ZINCALUME® is steel that is dipped in a zinc-based product to give it a protective coating.