Roofing Glossary

F

FELT
A fabric manufactured by the interlocking of fibers through a combination of mechanical work, moisture, and heat, without spinning, weaving, or knitting. Roofing felts are manufactured from vegetable fibers (organic felts), asbestos fibers (asbestos felts), or glass fibers (glass-fiber felts).
FERRULE
A metal sleeve used as a spacer to keep gutter from being deformed when secured to the fascia with spikes.
FIBERGLASS INSULATION
Insulation composed of glass fibers used to insulate walls and roofs. It can be rigid board or blanket insulation.
FISHMOUTH
An opening formed by an edge wrinkle in a sheet where it overlaps another sheet in a roofing membrane.
FLASHING
Connecting materials that seal the roof membrane at expansion joints, drains, gravel stops, and other places where the roof membrane is interrupted. Base Flashing forms the upturned edges of the watertight membrane at curbs and walls. Cap or counterflashing shields the exposed top edges of the base flashing.
FLASHING CEMENT
A trowel-able, plastic mixture of bitumen, reinforcing fibers, and solvent.
FLOOD TEST
A water test performed to determine the effectiveness of a roof covering..

G

GALVANIZED STEEL
Steel that is coated with zinc to aid in corrosion resistance. Galvanized steel for use in roofing should be Hot-Dipped Galvanized with a G-90 (1.25 oz/s.f.) coating.
GAUGE
A standard measurement. For instance the thickness of sheet metal or the diameter of wire. The thicker the wire or metal the lower the gauge.
GLASS FELT
In the manufacturing of roofing materials - a sheet comprised of bonded glass fibers before being saturated with bitumen.
GRAVEL
Aggregate consisting of rock fragments or pebbles.
GRAVEL STOP
Flanged device, usually metal, designed to prevent loose aggregate from washing off the roof and to provide a finished edge detail for the roofing assembly.
GUTTER
A channel (usually sheet metal) installed along the down-slope perimeter of a roof to convey runoff water from the roof to the drain leaders or downspouts.

H

HEAT WELDING
Fusing the seams of separate sections of roofing material together through the use of hot air or an open flame and pressure .
HOT OR "HOT STUFF"
Roofer's term for hot bitumen.

I

INSULATION
A material used to help maintain a certain temperature in a building by reducing the flow of heat from and to the building.

L

LAP
The part of the roofing material that overlaps a section of the adjacent material.
LAP SEAM
Where two materials that overlap are sealed together.
LEAD
Metal used for flashing material.
LOOSE-LAID ROOF MEMBRANES
Roofing material attached only at the perimeter and at penetrations and held in place by ballast, pavers, or other materials.

M

MEMBRANE
The portion of the roofing system that serves as the waterproofing layer. Can be composed of one material or several materials laminated together.
METAL FLASHING
Building components made from sheet metal that are used to terminate the roofing membrane or material along roof edges. Metal flashings are also used in the field of the roof around penetrations.
MINERAL-SURFACED SHEET
An asphalt-saturated felt, coated on one or both sides and surfaced in the weather-exposed side with mineral granules.
MODIFIED BITUMEN
a bitumen modified by one or more polymers, such as Atactic Polypropylene (APP) or Styrene Butadiene Styrene (SBS).
MOISTURE RELIEF VENTS
A vent installed through the roofing membrane to relieve moisture vapor pressure that has been trapped with the roofing system.
MOISTURE SCAN
A survey of a roof specifically to detect the amount of moisture present in the roof system. Infra-Red, electronic capacitance, and nuclear detection are three methods used in roof moisture surveys.
MOPPING
An application of bitumen applied hot with a mop or mechanical applicator to the substrate or to the felts of a built-up roofing membrane.

N

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.

P

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.