ROOFING TERMS

LEARN THE ROOFING LANGUAGE!

The assembly of materials used in building construction to reduce or retard the uncontrolled passage of air into and out of the building


BASE PLY

The bottom or first ply in a built-up or polymer-modified bitumen roof system when additional plies are to be subsequently installed

 

CAP FLASHING

(1) Usually composed of metal, used to cover or shield the upper edges of the membrane base flashing or wall flashing; (2) a flashing used to cover the top of various building’s components, such as parapets or columns. See FLASHING and COPING

 

CAP SHEET

A sheet, often granule-surfaced, used as the top ply of some built-up or polymer-modified bitumen roof membranes and/or flashings

 

CLOSED-CUT VALLEY

A method of valley application in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed back approximately 2 inches from the valley centerline

 

COLD-APPLIED

Designed for or capable of being applied without heating as contrasted to hot-applied. Cold-applied materials are furnished in liquid state, whereas hot-applied materials are furnished as solids that must be heated to liquefy before application

 

COLLAR

A metal cap flashing around a vent pipe projecting above a roof deck

 

COOL ROOF

A roof system that uses products made of highly reflective and emissive materials for its top surface. Cool roof surfaces can remain at markedly lower temperatures when exposed to solar heat in service than surfaces of roofs constructed with traditional non-reflective roofing products

 

COPING

The covering piece on top of a wall exposed to the weather, usually made of metal, masonry or stone

 

COUNTERFLASHING

Formed metal or elastomeric sheeting secured on or into a wall, curb, pipe, rooftop unit or other surface to cover and protect the upper edge of a base flashing and its associated fasteners

 

COVER BOARD

An insulation board used over closed cell plastic foam insulation (e.g. polyisocyanurate) to prevent blistering when used in conjunction with hot bituminous membranes. Suitable cover-board insulation are glass-faced siliconized gypsum board, fiberglass board, perlite board, wood fiberboard or mineral fiberboard. Cover boards are also recommended between polyisocyanurate insulation and single-ply membranes to protect the polyisocyanurate

 

CRICKET

A relatively small area of a roof constructed to divert water from a horizontal intersection of the roof with a chimney, wall, expansion joint or other projection

 

CURB

A raised member used to support roof penetrations, such as skylights, mechanical equipment, hatches, etc., above the level of the roof surface

 

DORMER

A structure projecting from a slope roofing usually housing a window or ventilating louver

 

DRIP EDGE

A metal flashing or other overhanging component with an outward projecting lower edge intended to control the direction of dripping water and help protect underlying building components

 

EXPANSION JOINT

A structural separation between two building elements that allows free movement between the elements without damage to the roof or waterproofing system

 

GABLE

The vertical triangular portion of the end of a building having a double-sloping roof from the level of the eaves to the ridge of the roof

 

GRAVEL STOP

A flanged device, frequently metallic, designed to prevent loose aggregate from washing off the roof and to provide a continuous finished edge for the roofing

 

HIP

The sloping line along the outer angle formed by the meeting of two sloping sides of a roof with eaves that meet at a right angle

 

OPEN VALLEY

A method of valley construction in which the steep slope roof covering materials on both sides are trimmed along each side of the valley, exposing the metal valley flashing

 

OVERFLOW DRAINAGE

Components(s) in a roof or waterproofing drainage system used to protect it against damage from a water load imposed by blocked or partially blocked primary drainage system; e.g. overflow scupper, overflow interior drain

 

PARAPET WALL

The part of a perimeter wall that extends above a roof

 

PENETRATION

(1) Any construction (e.g. pipes, conduits, HVAC supports) passing through a roof

 

PITCH-POCKET (PITCH PAN)

A flanged, open-bottomed enclosure made of sheet metal or other material placed around a penetration through the roof, properly stripped-in to the roof membrane and filled with grout and bituminous or polymeric sealants to seal the area around the penetration

 

PLY

A layer of felt or ply sheet in a built-up roof membrane or roof system

 

POLYISOCYNAURATE FOAM BOARD

A thermal insulation composed of polyisocyanurate foam with adhered facers; commonly called iso or isoboard

 

PONDING

The excessive accumulation of water at low-lying areas on a roof that remains after 48 hours after precipitation under conditions conducive to drying

 

POSITIVE DRAINAGE

The drainage condition in which consideration has been made during design for all loading deflections of the deck and additional roof slope has been provided to ensure drainage of the roof area within 48 hours of precipitation

 

PRIMARY DRAINAGE

Drainage devices, such as drains or scuppers, that provide for the direct removal of water from a waterproofing system

 

RE-COVER

The process of installing an additional roof covering over a prepared existing roof covering without removing the existing roof covering

 

REGLET

A sheet-metal receiver for the attachment of counterflashing. A reglet may be surface mounted, inset into a raggle or embedded behind cladding

 

SADDLE

A small tapered/sloped roof area structure that helps to channel surface water to drains; frequently located in a valley. A saddle is often constructed like a small hip roof or pyramid with a diamond-shaped base

 

SCUPPER

A drainage device in the form of an outlet through a wall, parapet wall or raised roof edge typically lined with a sheet metal sleeve

 

SELF ADHERING MEMBRANE

A membrane that can adhere to a substrate and to itself at overlaps without the use of an additional adhesive. The undersurface of a self-adhering membrane is protected by a release paper or film, which prevents the membrane from bonding to itself during shipping and handling

 

SQUARE

(1) A unit used in measuring a roof area equivalent to 100 square feet; (2) A quantity of material sufficient to cover 100 square feet of a roof deck

 

TORCH APPLIED

Method used in the installation of polymer-modified bitumen membranes characterized by using open flame propane torch equipment

 

UNDERLAYMENT

An asphalt saturated felt or other sheet material (may be self-adhering) installed between a roof deck and roof covering, usually used in a steep-slope roof construction. Underlayment is primarily used to separate a roof covering from the roof deck, shed water and provide secondary weather protection for the roof area of the building

VAPOR RETARDER

Layer(s) of material or a laminate used to appreciably reduce the flow of water vapor into a roof assembly