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NAILER: A piece of lumber, preferably treated, that is secured to the deck, walls, or to pre-manufactured curbs. Nailers are used to receive fasteners for roof systems.

NAILING PATTERNS: Refers to a specific method or pattern at which nails are applied. For instance, a nailing pattern for base sheets on plywood roof decks can be “Nine and Eighteen”. This means one of nails on the outside edge of the sheet set at nine inches (9”) on center, and two rows in the center of the sheet, each set at eighteen inches (18”) on center.  

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PARAPET WALL: The part of a perimeter wall that extends above the surface of the roof.

PENETRATION: Any object that projects through the surface of the roof.

PIPE BOOT: A prefabricated flashing piece used to flash around circular pipe penetrations.  

PITCH POCKET (A.K.A. Pitch Pan): A flanged, metal container placed around a column or other roof-penetrating element and filled with bitumen or other sealant to seal the joint.

POURABLE SEALER: A type of sealant that is initially in liquid form commonly used in conjunction with pitch pans to form a watertight barrier around penetrations that are difficult to flash.

PRIMER: A material that is applied to a surface to increase the bond strength of an adhesive to the surface.

PVC: Polyvinyl chloride, a thermoplastic resin used in the manufacture of many single ply roof membranes.  

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R-VALUE:  The measure of a material’s resistance to heat flow. The higher the R-value, the more effective its insulating property.

RE-COVER (OVERLAY): The installation of a new roof system over an existing system without removing an existing system.

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SATURATED FELT: Felt that has been saturated with bitumen.

SINGLE-LOCK STANDING SEAM: A vertical standing seam between two metal panels with one overlapping fold, as distinguished from a double-locked seam, which is folded twice.

SINGLE-PLY MEMBRANES:  Roofing membranes that are applied in one layer. Thermoplastic and thermoset(rubber) membranes are usually Single-Ply Membranes. Single-Ply membranes come in five basic types: (1) Ballasted, (2) Fully Adhered (3) Mechanically-Fastened (4) Partially Adhered, and (5) Self-Adhered. Seams of Single-ply Membranes can be heat welded, solvent welded, and adhered using seam tape or other adhesives.

SMOOTH-SURFACED ROOF: A roofing membrane surfaced with a layer asphalt or cold-applied asphalt-clay emulsion or asphalt cutback, or a synthetic coating.

SPLIT: A membrane tear resulting from tensile stress.

SOLID MOPPING: A continuous application layer of bitumen without voids.  

SPUD: To remove the top surfacing of a roof by scraping it with special tools called spud bars to power spudders.

SQUARE: A roof area of 100 sq. ft.

STRIPPING: (1) The technique of sealing the joint between metal and roof membrane with one or two plies of flashing membrane. (2) The technique of taping joints between insulation boards.

STAINLESS STEEL: A highly corrosion resistant steel alloy containing either chromium, nickel, or copper.

STANDING SEAM ROOF: A type of metal roof system where the longitudinal seams on adjacent panels are turned up, overlapped and folded in various ways in order to prevent moisture entry and interlock the panels.

SUBSTRATE: The surface upon which the roofing membrane is placed - structural deck or insulation.

SURFACING: The top-most layer of the roof system designed to protect the system from damage.

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TEAR-OFF: To remove a roof system down to the structural substrate.

TERMINATION BAR: A bar, usually metal or vinyl, used to seal and anchor the free edges of a roof membrane.

THERMAL SHOCK: The stress producing phenomenon resulting from sudden temperature changes in a roof membrane, when for example, a rain shower follows brilliant sunshine.

THROUGH-WALL FLASHING: A material that extends through a wall and is used to direct water entering a wall cavity to the exterior of the structure.

TIE-IN: The joining of two different roof systems. Also a “tie-off”.

TIE-OFF: A watertight seal used to terminate roof membranes at system adjuncts, terminations, flashings, or substrates. Can be temporary (Such as Night Seal) or permanent.

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UNDERLAYMENT: A material installed over the roof deck prior to the application of the primary roof coating. Usually consist of fifteen or thirty pound organic felt but can also be self-adhering such as an ice and water protection membrane.

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