Commercial Roofing Specialists

Serving Customers in and around the Twin Cities metro area since 1987.

Roofing Glossary of Terms

Commercial roofing terminology.

aggregate pavers: a surfacing or ballast for a roof system. Aggregate can be rock, stone, crushed stone or slag, water-worn gravel, crushed lava rock, or marble chips.

alligatoring: the cracking of the surfacing bitumen on a built-up roof that produces a pattern of cracks similar in appearance to an alligator’s hide.

aluminum: a non-rusting metal used in roofing for metal roofing and the fabrication of gutter and flashings.

Amalgamated™ Tapered Insulation System: a roofing system developed by Pinnacle Roofing Systems which uses multiple, increasing tapers that become steeper toward the edge of a flat roof in order to provide better insulation distribution, avoid ponding, and allow for more adequate drainage as roofs age.

asphalt: a bituminous waterproofing agent applied to roofing materials during manufacturing.

asphalt emulsion: a mixture of asphalt particles and an emulsifying agent such as bentonite clay and water.

ballast: a material installed over the top of a roof membrane to help hold it in place. Ballasts are loose laid and can consist of aggregate or concrete pavers.

batten: a strip of wood usually fastened to the structural deck for use in attaching a primary roof system such as tile; or a plastic strip, wood strip, or metal bar which is used to fasten or hold the roof and/or base flashing in place.

bitumen: any of various flammable mixtures of hydrocarbons and other substances, occurring naturally or obtained by distillation from coal or petroleum, that are a component of asphalt and tar and are used for surfacing roads and for waterproofing.

blocking: pieces of wood built into a roof assembly used to stiffen the deck around an opening, support a curb, or for use as a nailer for attachment of membranes or flashing.

boot: a piece of material preformed to protect roof penetrations from dirt, moisture, and other foreign and/or damaging substances.

built-up roof/BUR: a roof consisting of multiple layers of reinforcing membrane and waterproofing materials, such as asphalt and ply sheets.

cant strip: a continuous strip of material (triangular in cross-section) used as a transition piece between the roof deck and a vertical surface, normally with a 45 degree sloping surface; or a continuous strip of wood or fiber fitted into an angle formed at the intersection of a horizontal surface and a vertical surface.

cap flashing: material used to cover the top edge of base flashings or other flashings.

cap sheet: one to four plies of felt bonded and top coated with bitumen that is laid over an existing roof as a treatment for defective roofs.

contractor’s warranty: the written promise to the owner of the roof and roofing materials for workmanship involved in roofing or re-roofing a building.

curb: 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; or a raised roof perimeter that is relatively low in height.

deck: the surface installed over the supporting framing members to which the roofing is applied.

deterioration: having become disintegrated and impaired in quality, functioning, or condition.

drainage: the act, process, mode of, or device for draining.

drip edge: a non-corrosive, non-staining material or steel flashing bent at a 90 degree angle that is placed along the outer perimeter of steep sloped buildings; used along the eaves and rakes to allow water run-off to drip clear of underlying construction.

drippage: bitumen material that drips through roof deck joints, or over the edge of a roof deck.

eaves: the horizontal, lower edge of a sloped roof.

EPDM: Ethylene Propylene Diene Monomer; a thermoplastic rubber with high tear strength that can be cross-linked by both peroxides and sulfur.

evaluation: the careful appraisal of a roofing system to determine the condition and functionality of its various components and to recommend any necessary or potential need for repair or maintenance.

FM: an abbreviation of Factory Mutual Research Corporation; an insurance-industry, standards-setting laboratory.

fascia: vertical roof trim located along the perimeter of a building, usually below the roof level, for waterproofing or decoration.

flashing: components used to seal the roof system in places where the roof covering is interrupted or terminated – such as around pipes, curbs, walls, etc. – to help prevent moisture entry into the roof system or building.

flat roof: a non-peaked roof, typically used on industrial or apartment buildings, which appears flat but has a slightly tapered pitch.

HVAC: heating, ventilating, and air conditioning equipment.

inspection: the checking or testing of roof system and its components against established standards.

insulation: material used to maintain a desired temperature in a building by reducing the flow of heat into and out of the building.

maintenance: the periodic scheduled upkeep of a roofing system.

manufacturer’s warranty: the written promise to the owner of the roof and roofing materials for material-related problems.

membrane: the portion of the roofing system that serves as the waterproofing material.

new roof: an entirely new roofing system, usually placed on new construction.

parapet wall: the part of a perimeter wall that extends above the surface of the roof.

perimeter: the outer boundary of a roof or roofing system.

pipe boot: a prefabricated flashing piece used to flash around circular pipe penetrations.

pitch: the degree of slope or steepness of the roof.

polymer: any of numerous natural and synthetic compounds of usually high molecular weight consisting of up to millions of repeated linked units, each a relatively light and simple molecule.

ponding: the accumulation of water at low-lying or sagging areas of a roof.

proposal: a document stating the terms and conditions of a proposed roofing project submitted to a prospective client for approval and signature following a visual inspection of the project site and condition, or new building plans and specifications.

R-value: the measure of a material’s resistance to heat flow. The higher a material’s R-value, the more it insulates.

rakes: the inclined edge of a sloped roof over a wall from the eave to the ridge.

repair: the fixing of leaks, deterioration, cracks, and other such problems on an existing roof system.

re-roof: the replacement of a roof or portion of a roof, or the placement of additional roofing materials over an existing structure.

roof deck: the component in building construction which forms a platform on which the remainder of the BUR components are placed.

roof system: the entity made up of multiple roof components assembled to provide waterproofing, weatherproofing, and insulating for a building, including the waterproof covering, roof insulation, vapor barrier, and roof deck.

sag: settling or drooping of base flashings that have not been properly secured to a surface, or due to aging and deterioration, often occurring toward the center of a roof away from the perimeter.

scuppers: an outlet in the wall of a building or a parapet wall for drainage of water from a flat roof.

slope: the angle of incline of a roof.

straight tapered system: a slightly tapered roof in which the pitched surface sheds water toward a building’s perimeter.

substrate: the surface that the roof is installed upon.

termination: the sealed edges of a roof membrane.

underlayment: a layer of material (often tar paper) which is laid down on a bare deck before shingles are installed to provide additional protection for the deck.

white roof: a reflective roof that is more effective than traditional black asphalt roofs in keeping solar heat out of buildings and increasing energy savings.


Spande Construction Company

I have known Joel Nystrom for 20 years. I have done business with him and his company for that same time. I have worked with many companies in my years in the construction industry and found that not all have been the best to work with. Working with Joel has been my privilege. He has always been the best roofing company to work with. I used his company from small jobs to very large buildings. You can always count on Joel and his company to be there on the jobsite when scheduled and will finish the job as requested. His workmanship is unquestionably the best in the business. I have built many apartment buildings and commercial buildings and Joel was the first one I called for the roofing work.

I will always call on him to do my future roofing work. When looking for a reliable company to do your roofing work, do not hesitate to call him.

Gerald Spande

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