Metal Roofing Glossary: Common Roofing Terms You Should Know Defined

Our goal in this glossary is to provide you with a one-stop-shop defining Metal Roofing terminology.

Metal Roofing Glossary

Have you come across a metal roofing word and didn’t know what it meant? You are not alone! At Western States Metal Roofing, we have been selling metal roofing and siding panels for 25 years. As our company and industry continues to grow, we are continuously learning new words and terms to provide you with our knowledge.

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CAD – Computer Aided Drafting (CAD) is a design software that produces drawings to represent construction details.
Canopy – Any overhanging or projecting roof structure, typically over entrances or doors.
Cap Flashing – Used to cover or shield the upper edges of the membrane base flashing, wall flashing, or primary flashing; usually composed of metal.
Cladding – A material used as the exterior wall enclosure of a building.
Caulk – To fill a joint with mastic or asphalt cement to prevent leaks.
Chalk line – A line made on the roof by snapping a taut string or cord dusted with chalk. Used for alignment purposes.
Clamp – Clamps are small metal parts that are tightened and attached to the top of the metal roof at its standing seam.
Class “A” – The highest fire-resistance rating for roofing. Indicates roofing is able to withstand severe exposure to fire originating from sources outside the building.
Class “B” – Fire-resistance rating that indicates roofing materials are able to withstand moderate exposure to fire originating from sources outside the building.
Class “C” – Fire-resistance rating that indicates roofing materials are able to withstand light exposure to fire originating from sources outside the building.
Cleat – A piece of material typically used to elevate a finish material and/or used to protect that material during transport.
Clip – is a small metal component used to secure two pieces of metal to each other or to secure metal shingles or standing seam to solid decking.
Closed Valley – A valley that has an integral cover over the area where the shingles meet at the miter from adjoining roof planes. This valley carries water in hidden channels beneath the roof covering. In many cases, this cover creates a trap for debris such as leaves, ice, and snow to gather and clog the valley system, causing water to overflow underneath the roofing system
Coatings – A layer of material spread over a surface for protection or decoration.
Cohesion – The degree of internal bonding of one substance to itself.
Coil – A finished steel product such as sheet or strip which has been wound or coiled after rolling.
Coil Coating – The continuous process in which paint is applied to both sides of a moving strip of metal. The process usually includes cleaning, chemical pre-treatment, primer, and topcoat.
Cold Roof – A roof incorporating “above sheathing ventilation” in order to help prevent hot spots on the roof and subsequent wintertime ice dams.
Collar/Boot – Pre-formed flange placed over a vent pipe to seal the roof around the vent pipe opening. Also called a pipe boot.
Column Wrap – A formed metal panel to enclose a wood or steel column.
Combustible – Materials capable of burning.
Concealed Fastener – A fastening clip system that is hidden beneath the metal panels.
Condensation – The process where water vapor becomes liquid. It occurs when warm moist air hits a cool surface. This can occur in or on poorly designed roof assemblies.
Cool Roofing – Roofs that have high reflectivity achieved either through light colors or reflective pigments. Can also refer to roof systems which have integral ventilation to help carry heat away from the structure and reduce cooling loads.
Copper – A natural weathering metal used in roofing.
Corner Trim – A formed piece of metal used to enclose the corners of a metal panel; typically placed vertically.
Corrugated Metal Roofing – A metal sheet that is roll-formed into a metal panel. These panels are then attached to the roof with screws. The traditional shape of corrugated sheet metal is round and wavy.
Corten® – Trademark name given to a weathering steel alloy material originally produced by United States Steel. Corten Steel is a group of steel alloys that are often used in outdoor construction. It was designed to eliminate the need for painting and if left outside, exposed to the elements, they will develop a rusted appearance in just a few months.
Counter flashing – That portion of the flashing attached to a vertical surface to prevent water from migrating behind the base flashing.
Course – A row of metal shingles running the length of the roof.
Coverage – The surface area covered by a specific quantity of a particular material.
Cricket – A peaked “saddle” constructed at the back of a chimney to prevent accumulation of snow and ice and to deflect water around the chimney.
Cupola – A small structure added to a building's ridge for ventilation or as a decorative accent.
Curb – An accessory used to mount additions and provide a level resting structure on a sloped roof.

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Fading – Any lightening of the initial color
Fascia – Caps the perimeter of the gables and eaves of the roof, can then be used to hang gutters along the eaves.
Fasteners – A wide variety of mechanical securement devices and assemblies, including nails, screws, cleats, clips, and bolts, which may be used to secure various components of a roof assembly.
Felt – A flexible sheet that is saturated with asphalt and used as an underlayment, sometimes called “tar paper”.
Field Forming – Used when the materials can be formed at the job site.
Finishes – A surface coating used to coat the surface of metal panes.
Fire Resistance – The property of materials or their assemblies that prevents or retards the passage of excessive heat, hot gases or flames under conditions of use.
Fixed Clip System – A formed metal component anchored to the building substrate used to secure two pieces of metal to each other or to secure metal shingles or standing seam roofing.
Flange – A metal edge that is typically 90 degrees perpendicular to the bent shape.
Flashings – Components used to help waterproof the perimeters and protrusions in a roofing system.
Flashing cement – Sealant designed for use around flashing areas as a component in the flashing system.
Flat Sheet – Metal formed by an industrial process that is formed into flat pieces.
Floating Clip System – A formed metal component anchored to the building substrate used to secure two pieces of metal to each other or to secure metal shingles or standing seam roofing.
Foam Closure – An extruded foam piece formed from neoprene or polyethylene and conforms to the uniform bends of a metal panel to prevent wind, insect, and moisture damage.

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R Panel – 36” wide metal panel with raised ribs and a flat area between the ribs. It does not have a purlin bearing leg so it’s typical application is a wall panel. See PBR Panel for roofing applications.
Rafter – The supporting framing member immediately beneath the deck, sloping from the ridge to the eave.
Rake – The inclined edge of a sloped roof over a wall from the eaves to the ridge. These two slopes meet at the peak or ridge.
Re-cover (overlay) – The installation of a new roof system over an existing system without removing an existing system.
Re-roofing – Installing a new roof system on a building that is not new.
ReziBond® – Hot dip galvanized steel (HDG) that has been coated with a proprietary combination of acrylic resins, heavy metals, and flatteners. This process produces a dull gray colored finish.
Ridge – The very top section of the roof running the length of the roof, where the two roof slopes come together.
Ridge Caps – Accessories used to cover the inclined external angle formed by the intersection of two sloping roof planes, either at the ridge or hip. Also called “hip caps”.
Ridge Vent – An outtake vent for air integrated into the ridge flashing. A ridge vent’s proper performance requires intake adequate intake vents, usually in the eave soffits of the home. For most homes this is the most effective method for siphoning air out of the attic or other air space.
Rise – The vertical distance from the eave line to the ridge.
Rollforming Equipment – The machinery that forms and shapes the coil into individual panels.
Roof Assembly – An assembly of interacting roof components such as roof deck, vapor retarder, insulation, and roof covering.
Roof Framing Styles – The different shapes and designs a roof can take, such as gable, hip, or barn.
Roof Plane – An even roofing area defined by having separate edges. One side of a gable, hip, or mansard roof.
Run – The horizontal distance from the eaves to a point directly under the ridge. One half the span.

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Sealant – Used most commonly to act as a sealant of joints or cracks to help prevent leaks. The higher grade sealants are usually butyl or polyether chemistry. Sealants should be used for aesthetic reasons as well as for redundant lines of defense against water intrusion. They should never be the sole line of defense. Also, sealants are not designed to be adhesives.
Self-Adhering Membrane – A material layer that can adhere to a substrate and to itself at overlaps without the use of an additional adhesive.
Self-Drilling Screw – A fastener that drills and taps its own hole during application.
Self-Tapping Screw – A fastener that forms receiving threads when turned into a previously drilled hole.
Sheathing – Exterior grade boards used as a roof deck material.
Shed roof – A roof containing only one sloping plane. Has no 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. Also referred to as “pitch”.
Slope Applications – The application of roofing materials to a roof based upon its slope or pitch. Can be achieved through “steep slope application, “normal slope application” or “low slope application”.
SMP or Siliconized Polyester – A type of coating consisting of a solvent-based system with polyester resin. Silicone additives are used to increase resin stability and coating flexibility. Standard polyester finishes are commonly used on agricultural metal roofs where price is of greater concern than performance.
Snap-lock – Metal roofing panels that have been carefully rolled formed with specific panel profile edges that snap together and require no hand or mechanical seaming during installation.
Snow Guard – Used in snow country to help break apart snow so it does not slide off the roof in large pieces. On standing seam roofs, these items need to be installed in a way that does not impede movement of the roofing system with thermal expansion and contraction. Also referred to as “snow break”.
Soffit – The finished underside of the eaves.
Solar Mounting System - Support system to sustain solar panels on a roof.
Solar Reflectance – The ability of a roof to reflect solar heat.
Solar Reflectance Index (SRI) – A measure that combines a constructed surface’s ability to reflect solar radiation and emit thermal radiation.
Square – Enough product to cover approximately 100 square feet of the roof.
Span – The horizontal distance from eaves to eaves.
Standing Seam – A seam made by turning up two adjacent edges and folding the upstanding parts over on themselves.
Standing Seam Roof System – A type of metal roof that typically has panels run vertically with a raised, interlocking seam which joins one panel to the next. The roof panel system is secured to the roof substructure by concealed clips attached with screws to the substructure.
Starter Strip – Used to begin the attachment of many metal roofing systems. It is used at the eave (bottom) of the roof on many metal shingle systems and on the left hand edge of the roof on many standing seam systems.
Steep slope application – Method of installing roofing material on roof slopes greater than 21 inches per foot.
Steep-Slope Roofing – Generally roofs with slopes higher than 4/12.
Step Flashing – A method of flashing commonly used with standard roofing shingles and some other materials. Step flashing is generally not advised with metal roofing which usually uses continuous lineal flashings for greater life and watertightness.
Stone Coated – Metal roofing made from zinc or aluminum coated steel that is then coated with the same granules as composition shingles. It is attractive but faces similar problems of streaking, granule loss, and organic growth as traditional composition shingles.
Striation – Ribs or waves formed into metal panels to minimize oil canning.
Structural Roofing – refers to metal roofing that provides structural integrity to the building and does not require decking for installation. Generally these systems are not advised for residential application because a lack of decking can be a contributing factor to condensation issues.
Substrate – The surface upon which the roofing or waterproofing membrane is applied.
Super Polyester – A type of coating. Siliconized polyester with fade resistant pigmentation. The pigments enhance the performance of traditional polyesters, but the coatings are still prone to chalking as the resin breaks down over time.
Swarf – Metal shavings and chips that are caused by cutting and drilling roof panels. These fragments tend to rust quickly if they are not removed from the roof in a timely manner

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