102 Roofing Terms You Should Know

Every industry has its own terminology, and commercial roofing is no exception. Listening to your contractor talk about how he recommends we "fully adhere the single-ply membrane to the substrate to make it more resistant to racking" probably has you asking for an explanation.

That's why we've compiled this glossary of commercial roofing terms. Below you'll find over 100 important roofing terms, organized alphabetically.

1. Acoustic Insulation: Material that reduces sound transmission.
2. Adhesion: The bonding of one material to another.
3. Aggregate: Crushed stone, slag, or gravel that is used to surface built-up or single-ply roofs.
4. Anchor Sheet: A mechanically fastened base sheet in a partially adhered or mechanically attached single-ply roof system.
5. Asphalt: A sticky, black, and viscous liquid or semi-solid form of petroleum used for roofing.
6. Backrolling: The process of using a roller to further distribute and embed a coating after it has been sprayed.
7. Ballast: An anchoring material, such as aggregate, or precast concrete pavers, which employ the force of gravity, and sometimes a binder, to hold roofing elements in place.
8. Ballasted Roof System: A roofing system in which loose, heavy materials hold down a single-ply membrane.
9. Batt: A section of fiberglass or rock wool insulation.
10. Bitumen: The binder that holds asphalt together. 
11. Blister: A raised spot on the surface of an SPF or roof coating system, usually caused by the expansion of gas or liquid within the foam.
12. Blistering: Bubbles or pimples in roofing materials.
13. Built-Up Roof (BUR): A roofing system made up of layers of asphalt and a reinforcing fabric.
14. Closed-Cell Foam: A type of foam where the cells are enclosed and packed together tightly. It's typically stronger and more resistant to water penetration compared to open-cell foam.
15. Cool Roof: A roof that reflects more sunlight and absorbs less heat.
16. Coping: The covering on top of a wall that is exposed to the weather, usually made of metal, masonry, or stone.
17. Counterflashing: The part of the flashing that's goes against a vertical surface to prevent water from migrating behind the base flashing.
18. Cross Ventilation: Air movement through a space in multiple directions.
19. Crystalline Waterproofing: A technology that uses a reactive crystalline compound for sealing and enhancing the durability of concrete.
20. Dead Level: Absolutely horizontal or zero slope.
21. Deck: The part of a building on top of which the roofing system is installed.
22. Density: In the context of SPF, it's the weight per cubic foot of the foam, often categorized into low and high density.
23. Dew Point: The temperature at which dew is produced. This is important when applying SPF or roof coatings as it can affect adhesion and curing.
24. Drum Set: A term referring to the two chemical components (isocyanate and resin) used to create the polyurethane foam, often sold in large drums as a set.
25. Edge Detail: A term used to describe the specific design or type of edge.
26. Elastomeric: Capable of returning to the original shape after being stretched.
27. Elastomeric Coating: A coating that can stretch and return to its original shape without damage, often used to protect the SPF layer.
28. EPDM (Ethylene Propylene Diene Monomer): A type of synthetic rubber used in single-ply roofing.
29. Expanded Polystyrene (EPS): A type of rigid foam insulation that is less expensive and has a lower R-value than XPS.d foam
30. Extruded Polystyrene (XPS): A type of rigi insulation that has a closed cell structure and offers greater resistance to moisture and a higher R-value than EPS.
31. Felt: A fabric, often made of wool, used as a layer in some types of roofing.
32. Fiberglass: A type of insulation material made from fine glass fibers.
33. Fire Resistance Rating: A rating that indicates a material's resistance to fire or slow burning. This is often considered in selecting insulation for commercial buildings.
34. Flashing: A material used to prevent water intrusion at areas of interruption in the membrane, such as around vents or chimneys.
35. Foam-in-Place Insulation: A type of insulation that is blown into walls or under roofs, expanding and hardening into an insulating layer.
36. Galvanic Action: An electrochemical action that takes place when different kinds of metals are in contact in the presence of an electrolyte, resulting in corrosion.
37. Gutter: A channel installed along the perimeter of a roof to move water from the roof to the drains or downspouts.
38. Hydrostatic Pressure: The pressure exerted by a column of water on an underlying surface.
39. Ice Dam: Ice that forms along the lower edge of roof slopes and impedes the flow of water off the roof.
40. Infrared Thermography: The use of an infrared camera to measure the temperature of a roof surface and locate areas of trapped moisture.
41. Insulating Concrete Forms (ICFs): Forms made from foam insulation that are filled with concrete, providing a well-insulated and airtight wall system.
42. Insulation: A material used in construction to impede heat transfer.
43. Insulation Board: A board made of insulating material used in roofing applications for energy efficiency purposes.
44. Joist: The metal or wood beams that run parallel from wall to wall to support the roof of a building.
45. Lap Seam: Where the end of one roll or sheet overlaps the end of the adjacent roll or sheet.
46. Live Loads: Temporary loads the roof structure must be able to support during maintenance or construction, as required by local building codes.
47. Loose Fill Insulation: Small particles of fiber, foam, or other materials that are blown into building cavities or attics using special equipment.
48. Low-Slope Roof: A roof that is slightly inclined, typically with a slope ratio of 3:12 or less.
49. Membrane: A roof covering or waterproofing layer designed to prevent water intrusion.
50. Mil: A unit of measurement used in the coating industry to determine thickness. One mil equals one-thousandth of an inch.
51. Mineral Wool: Insulation made from molten glass, stone, or industrial waste that is spun into a fibrous structure.
52. Modified Bitumen: A type of asphalt that can be applied to a roof to create a durable a roofing membrane.
53. Moisture Relief Vent: A vent installed through the roofing membrane to release vapor pressure from within the roofing assembly.
54. Nail Pop: A raised fastener in the roof membrane's surface.
55. Open-Cell Foam: A type of foam where the cells aren't completely enclosed, resulting in a softer and less dense material that is vulnerable to water penetration.
56. Overspray: Unintended SPF or coating that lands outside the intended application area.
57. Parapet: A low wall that extends slightly above the roof along the perimeter.
58. Pass: A single continuous spray application of SPF or coating.
59. Penetration: Any object passing through the roof, like a chimney, HVAC unit, or skylight.
60. Perlite: A natural, lightweight, insulating aggregate.
61. Permeability: The rate at which water vapor can pass through a material.
62. Pitch: The steepness of the roof.  Mathematically, the ratio of the rise to the span, in feet.
63. Ply: The number of layers of roofing felt, of a roofing membrane, or of layers in built-up materials or any finished piece of material.
64. Polyisocyanurate (Polyiso): A thermoset plastic typically produced as a foam and used as rigid foam board thermal insulation.
65. Polystyrene: A type of plastic used to make rigid foam insulation panels.
66. Ponding Water: Water that remains on a roof surface for 48 hours or more.
67. Primer: A coating applied to a substrate before the application of SPF or protective coating to improve adhesion.
68. PVC (Polyvinyl Chloride): A very tough single-ply roofing material that is resistant to many chemicals and pollutants.
69. Racking: The movement of a building's roof due to forces such as wind, seismic activity, and snow loads.
70. Ratio Check: The process of confirming the proper ratio of SPF components to ensure optimal performance.
71. Recoat: The process of applying a new protective coating to an SPF or roof coating system after the initial one has weathered.
72. Recoat Window: The timeframe within which a second layer of SPF or coating can be applied without additional surface preparation.
73. Reflective Insulation: Insulation that reduces heat transfer by radiation.
74. Rigid Foam Board Insulation: Insulation that is typically more expensive than batt insulation but very effective in exterior wall sheathing, interior sheathing for basement walls, and more.
75. Roof Assembly: All of the interconnected components of a roof, (including the deck, vapor retarder, insulation, and roof covering) designed to weatherproof and, sometimes, to improve the building's thermal resistance.
76. Roof Covering: The exterior roof cover or skin of the roof assembly, consisting of membrane, panels, sheets, shingles, tiles, etc.
77. Roof Hatch: An opening in the roof with a secure cover that allows access between the interior of a building and the roof.
78. Roof Seamer: Machines that are used to seal lateral seams in metal roofing.
79. Roof System: All of the components required to fully protect the topside of a building.
80. Scupper: An opening in the parapet wall allowing water to drain from the roof.
81. Seam: A joint formed by bringing two separate sections of material together.
82. Single-Ply Membrane: Roofing membranes consisting of just one layer of membrane material rather than multiple.
83. Slope: See pitch.
84. Soffit: The underside of the eaves.
85. SPF (Spray Polyurethane Foam): A type of roofing material that is sprayed into place and forms a continuous, seamless layer that insulates and waterproofs the roof.
86. SPF Blister: An SPF roofing defect where a void forms between the SPF layers or between the SPF and substrate.
87. Standing Seam: A type of metal roofing system where the seams between the panels are raised above the roofing surface.
88. Structural Insulated Panels (SIPs): A panel consisting of an insulating layer sandwiched between two structural facings, typically made of plywood or OSB.
89. Substrate: The surface to which the membrane is applied.
90. Synthetic Underlayment: A sheet material used between the roof deck and the roofing material.
91. Tear-Off: Removal of an existing roof system down to the structural deck.
92. Thermal Bridging: Areas in a building's construction where insulation is incomplete or missing, causing heat to escape or enter the building.
93. Thermoforming: A process of heating and shaping synthetic materials.
94. TPO (Thermoplastic Polyolefin): A type of single-ply roofing membrane.
95. U-value: A measure of the rate of heat transfer through a material or system. The lower the U-value, the greater a material's resistance to thermal transfer and the better its insulating capacity.
96. Underlayment: A material laid on the roof deck before installation of the primary roof covering.
97. Vapor Barrier: Material designed to resist diffusion of moisture through walls, ceilings, and floors.
98. Vermiculite and Perlite Insulation: Insulation materials that are naturally occurring minerals that are heated to expand and used as insulation.
99. Water Cure: A curing method for SPF involving the application of a mist of water to the foam surface.
100. Workmanship: The quality and configuration of a roofing system as it is applied by a contractor.
101. XPS Insulation: Extruded polystyrene insulation is a rigid, closed-cell foam panel insulation.
102. Zonal Nailing: The practice of nailing the perimeter and field of a roof deck with different nail spacing.

The Upshot

With a myriad of terms relating to materials, processes, and technical aspects of the field, anyone can feel a bit lost when researching their commercial roofing options, but with our helpful glossary, you should be able to find the definition of almost any technical term you come across.

Now that you are equipped with this newfound knowledge, the next step is to put it to practical use. If you are thinking about a new roofing project or just want to better understand the one you currently have, reach out to our team at GIDEON. Schedule a consultation, ask for more information, or simply get advice - we're here to assist you.