NRCA ProCertified Asphalt Shingle Installer key terms

An assembly of harness, connecting device, and anchorage that stops a worker's fall and limits arrest forces. On roofs it must be rigged so a fall is stopped before the worker contacts a lower level or the ground.

A structurally verified attachment location, such as a manufactured roof anchor, rated to resist the forces of a fall arrest event. It must be independent of the work platform and capable of supporting the required load without failure.

A site-specific written plan for roof work that identifies fall hazards and the methods used to control them, including conventional fall protection or a documented alternative for narrow or steep roofs where standard systems are infeasible.

A barrier of ropes, wires, or chains with high-visibility flags, erected at a set distance back from the roof edge. It is a fall protection option for low-slope roofs and does not physically stop a fall.

A temporary or permanent barrier of top rail, midrail, and toeboard installed along an unprotected roof edge or opening. It provides passive protection, so workers need no personal equipment to be protected from falling.

The practice of setting ladders on stable footing at the proper angle, extending them above the roof edge, and securing them. Three-point contact means keeping two hands and one foot, or two feet and one hand, on the ladder while climbing.

Temporary staging devices, such as roof jacks, brackets, and toe boards, that create a level work surface and catch materials on a sloped roof. They must be installed into sound framing or sheathing and removed without leaving holes unsealed.

An opening in a roof covered by glass or plastic that may look solid but will not support a person. It must be guarded with a cover rated for the load or protected by a guardrail or personal fall arrest system before work begins.

The pre-installation check of sheathing for rot, delamination, loose fasteners, and span adequacy, plus verification that framing and deck thickness meet code and manufacturer requirements. Repairs must be completed before underlayment and shingles are installed.

The structural roof boards, usually plywood or oriented strand board, that span rafters and receive fasteners. Thickness and span rating must satisfy code and shingle manufacturer requirements, and damaged panels must be replaced rather than covered.

The downward bending of roof sheathing or framing under load. Excessive deflection cracks shingles and opens fasteners, so framing and panels must be stiff enough for the design load and the finished roof covering.

The specified pattern and spacing of nails or screws used to attach sheathing to framing. It is set by code and the panel manufacturer and must be verified before underlayment because missed fasteners cause squeaks, humps, and shingle damage.

A water-shedding layer between the deck and the shingles, commonly an asphalt-saturated felt or synthetic sheet. It provides a secondary barrier and must be installed with the correct overlap, fastening, and coverage for the roof slope.

A self-adhering waterproofing sheet installed along eaves, in valleys, and around penetrations where water can back up and freeze. It must be placed over the deck and under the underlayment in the widths required by code.

A metal flashing at the eave and rake edges that directs water away from the fascia and into the gutter. It is installed under the underlayment at the eave and over it at the rake, depending on the manufacturer's detail.

The eave is the lower roof edge that overhangs the wall and usually carries the gutter; the rake is the sloping edge along a gable. Both edges require specific flashing and shingle treatment to shed water and resist wind uplift.

A first row of shingles or starter strip installed along the eave and rake that seals the bottom edge of the roof and resists wind uplift. It is laid over the underlayment and beneath the first full shingle course.

The shingle or starter strip placed along the sloping gable edge so the first field course has a sealed, finished edge. It is cut or manufactured to align with the rake flashing and must be fastened in the shingle's specified nailing area.

The area on a shingle, marked by the manufacturer, where fasteners must be placed to hold the shingle without tearing it. Nails placed above or below the zone reduce wind resistance and can damage the shingle below.

The requirement that nails be driven straight, flush with the shingle surface, and penetrate the deck or previous course by the specified amount. Overdriving cuts the shingle; underdriving leaves the head proud and prevents sealing.

An enhanced fastening pattern, such as additional nails per shingle or closer spacing, required by the manufacturer or code for roofs in high-wind zones. It is paired with a wind-rated shingle and a sealed starter course.

A shingle system's ability to resist being lifted by wind, expressed as a rated wind speed and achieved through correct nailing, starter course, sealing strips, and edge metal. Ratings assume installation exactly matching the manufacturer's instructions.

Headlap is the vertical overlap between courses; sidelap is the horizontal overlap between shingles in a course. Correct laps shed water and prevent leakage at joints, and they must match the manufacturer's exposure and installation instructions.

The portion of a shingle left uncovered by the course above, measured vertically and set by the manufacturer. Too much exposure exposes the sealant strip and weakens the roof; too little wastes material and may void the warranty.

Metal or membrane material used to weatherproof joints where the roof meets walls, chimneys, valleys, and penetrations. Flashing must be layered with the underlayment and shingles so water flows over, not behind, the material.

Individual L-shaped metal pieces interwoven with each shingle course along a sidewall or chimney. Each piece sheds water onto the shingle below while the shingle above laps over it, creating a shingle-like drainage path.

Flashing set into a masonry wall or chimney above the roof surface, lapping over the base or step flashing below. It keeps water from entering behind the lower flashing and must be sealed and terminated correctly at its top edge.

The complete flashing assembly around a chimney, including base flashing on the roof, step flashing on the sides, counterflashing in the masonry, and a cricket on the uphill side. It must be integrated with the shingle courses and underlayment.

A small peaked roof built on the uphill side of a chimney or other projection to divert water around it. It is required when the chimney is wide enough that water would otherwise collect and penetrate the roof.

The flashing in the internal angle where two roof slopes meet, lined with metal or membrane and covered by shingles in an open or woven pattern. It must carry concentrated runoff and be installed per the manufacturer's valley detail.

A valley treatment where the metal pan remains visible between shingle edges trimmed back from the center line. It sheds water and debris quickly and must be installed with the correct metal width, fastening, and shingle setback.

A valley treatment where shingles from both roof planes are interlaced across the valley center. It hides the flashing, requires careful course alignment, and must follow the manufacturer's instructions for nailing and overlap.

A compatible sealant, boot, or flashing collar used where pipes, vents, or fasteners pass through the roof. It must be installed over the underlayment and integrated with the shingle courses so water cannot run behind it.

The combination of intake and exhaust openings that moves air through the attic to remove heat and moisture. Balanced intake and exhaust area, sized to code, protects the deck and shingles and reduces ice damming.

The required relationship between the net free ventilating area and the attic floor area, commonly expressed as 1:150 or 1:300. It is set by code and depends on vent type, placement, and whether a vapor retarder is present.

A continuous exhaust vent installed along the ridge, covered by ridge cap shingles. It works with soffit intake vents to create a convection flow and must be sized and installed to the manufacturer's instructions.

Moisture that forms when warm, humid air meets a cold roof deck, often because exhaust ventilation is blocked or intake is inadequate. It can rot sheathing and stain ceilings and is prevented by correct venting and air sealing.

The written requirements for a specific shingle product covering nailing, exposure, underlayment, flashing, and ventilation. Following them is necessary for the product warranty and is often required by code as a condition of approval.

Adherence to the locally adopted code, such as the International Residential Code, for roof covering, flashing, ventilation, and fastening. The stricter of code or manufacturer instructions governs, and local amendments may add requirements.

The authorization and official review required before and after certain roof work. Inspectors verify deck condition, underlayment, flashing, and fastening at stages the code specifies, and work must not be covered before approval.

The systematic check of a finished or existing roof for missing or damaged shingles, exposed fasteners, poor laps, flashing gaps, and ponding. Findings are documented and classified by severity so repairs and reports are accurate.

Standing water on a low-slope roof that does not drain within the time allowed by code. It accelerates deterioration and signals inadequate slope, clogged drains, or deflection that must be corrected rather than covered.

Surface conditions where mineral granules are shed or the shingle mat lifts into blisters. They can result from manufacturing defects, trapped moisture, or foot traffic, and their extent and pattern help determine whether repair or replacement is needed.

A written record of incomplete or defective items found during final inspection, with location, description, and corrective action. It supports communication with the client and provides evidence that repairs were completed before closeout.

Dated images of deck conditions, flashing details, and completed work taken before areas are covered. They support inspection reports, warranty claims, and dispute resolution by showing the condition at each stage.

A written agreement signed by the client authorizing work added to or removed from the original scope, with the effect on price and schedule. It protects both parties when concealed damage or upgraded materials are discovered.