NRCA Metal Shingle key terms

A steep-slope roof covering made of formed metal panels stamped or folded to look like individual shingles, installed as overlapping units or interlocking courses over a prepared deck.

The fixed repeat width of a metal shingle unit, including its exposed face plus the side lap it covers, used to calculate coverage per piece and course layout.

The vertical height of shingle face left visible to the weather after the next course above is installed; it controls course count and total material quantity.

The distance the upper course overlaps the top of the course below, providing the primary barrier against wind-driven rain at horizontal joints.

The horizontal overlap where one shingle unit covers the edge of the adjacent unit in the same course, sealed by interlock, sealant, or concealed fastening.

A metal shingle with formed folded edges that engage the neighboring panel to resist wind uplift and shed water without exposed side fasteners.

The steel or aluminum sheet from which a metal shingle is formed; its thickness and alloy determine stiffness, dent resistance, and fastener holding power.

An aluminum-zinc alloy coating applied to steel coil for corrosion protection; coating weight class is specified by the manufacturer and affects expected service life in coastal or industrial settings.

A factory-applied polyvinylidene fluoride (PVDF) coating known for color retention and chalk resistance on steep-slope metal roofing; touch-up must use matching manufacturer product.

Factory-matched coating supplied for field repair of scratches and cut edges; application limits and cure requirements come from the panel manufacturer, not generic paint.

An exposed uncoated edge created by field cutting or shearing a panel, which is more vulnerable to corrosion and is normally hidden in a lap or covered by trim.

The published written instructions governing approved substrates, underlayment, fasteners, laps, and flashing for a specific metal shingle product; it controls over generic trade practice.

A third-party document (such as an ICC-ES report) confirming that a listed metal shingle system meets specified code sections when installed per the manufacturer's published instructions.

The specific combination of deck, underlayment, panels, fasteners, and flashings recognized in the code or an evaluation report as a tested, acceptable roof system.

A written site document identifying fall hazards, the chosen fall arrest or restraint systems, anchor points, rescue procedures, and the competent person responsible for enforcement.

Harness, connecting device, and anchor arranged to stop a fall within allowable distance and arrest force; required where workers are exposed to falls at or above the trigger height.

A structurally verified attachment for lifelines or lanyards, rated for the required load and located so a fall is arrested before the worker strikes a lower level or edge.

A horizontal or vertical line rigged between anchors to which workers tie off, allowing travel along the roof while maintaining continuous fall protection.

A barrier of posts and flagged line set back from the roof edge to mark a controlled zone; it is a restraint measure with specific height and setback rules, not a substitute for arrest in all cases.

A temporary staging device hooked over the ridge or nailed to the deck to support planks and materials on steep slopes, reducing trips and falls during shingle installation.

A low temporary board at the roof edge that stops tools and materials from sliding off and gives workers a visual edge cue; it is not a fall arrest device.

The structural surface receiving underlayment and metal shingles; solid sheathing is typical, and its thickness, span rating, and fastener schedule are set by code and manufacturer requirements.

The downward bending of roof sheathing under load; excessive deflection can crack coatings, open laps, and fatigue fasteners, so span ratings must match panel weight and snow load.

A sheet membrane laid over the deck beneath metal shingles to shed water that passes the panels and to separate metal from resinous or chemically incompatible sheathing.

A synthetic membrane rated for elevated surface temperatures, used where metal panels transfer heat to the deck and standard asphalt felt would soften or bleed.

A self-adhering waterproof membrane installed along eaves and in valleys to prevent meltwater backup from entering the roof where ice forms at the eave.

A horizontal row of metal shingles installed across the roof slope; courses stack upward with consistent exposure so laps align and water sheds downward.

A snapped reference line used to establish the first course, vertical panel alignment, and accessory placement so cumulative error does not skew the roof layout.

Placement of the specified screws or nails at the manufacturer's locations and spacing, driven to the required depth without overdriving, to secure panels while allowing intended movement.

The manufacturer's table of fastener type, length, diameter, and spacing for each location such as field, perimeter, and ridge, based on wind zone and deck type.

A panel system's tested ability to resist negative pressure that lifts shingles from the deck; ratings depend on fastener pattern, panel profile, and edge restraint.

The internal intersection where two roof slopes meet; metal shingles are cut and flashed to a valley pan or woven detail that directs concentrated runoff without trapping water.

A formed metal channel lining a valley beneath the shingle courses, sized and lapped per manufacturer instructions so runoff is carried over the underlayment to the eave.

L-shaped metal pieces installed in courses with each shingle along a sidewall, shedding water onto the roof surface while keeping the wall-to-roof joint weathertight.

Metal attached to the wall or masonry above step flashing and bent down over it, shielding the top of the flashing from water entry behind the wall cladding.

A continuous metal piece at the base of a wall, chimney, or curb that underlies the shingles and step or counter flashing, closing the joint against water entry.

Drip edge, rake trim, and eave closure profiles that finish the roof perimeter, direct water clear of the fascia, and restrain panel edges against wind.

A formed metal strip at the eave and rake that projects past the sheathing to release water away from fascia and wall, installed in the lap order the manufacturer requires.

A preformed flashing collar sealed to a vent pipe and lapped into the shingle courses so water runs around the penetration rather than behind it.

Any pipe, stack, or fastener passing through the roof surface; each must be flashed with a listed component lapped into the shingles in the direction of water flow.

A specified caulk or tape used only at locations the manufacturer approves, applied to clean dry surfaces; it supplements mechanical flashing and is not a primary water barrier.

Expansion and contraction of metal panels with temperature change; accommodated by slotted or oversized fastener holes, free laps, and panel lengths kept within manufacturer limits.

Balanced intake at the eave and exhaust near the ridge that removes heat and moisture from the attic, protecting deck and shingles and reducing condensation risk.

Exhaust venting installed along the ridge, baffled against rain and snow, sized to match net free intake area so the attic ventilates without pressurizing the roof assembly.

Formed metal covering the ridge that laps over the top course of shingles and integrates with ridge venting while closing the joint against weather.

A material limiting moisture vapor diffusion into the roof assembly from below; its placement and permeance must suit the climate so the deck does not trap moisture.

Water formed when moist air cools on a cold surface such as the underside of metal panels or sheathing; controlled by ventilation, vapor control, and interior humidity management.

A non-destructive inspection method using meters or infrared imaging to locate trapped moisture in the roof assembly before repairs or warranty claims are accepted.

A replacement shingle unit matched to the existing profile, coating, and color, installed by reversing the removal sequence and restoring laps and fasteners.

Failure of a fastener to hold in the deck, often from thin sheathing, overdriving, or wrong fastener type; checked during inspection by verifying engagement and resistance.

Standing water on a roof surface caused by inadequate slope, blocked drainage, or deflected framing; on steep-slope metal it signals a defect requiring correction, not a coating patch.

A worker designated by the employer who can identify hazards and has authority to take prompt corrective action, including stopping work when fall or fire risks are unsafe.

A written authorization required before cutting, grinding, or soldering that can ignite materials; it verifies fire watch, extinguisher placement, and clearance around combustible underlayment.

A folded edge formed on cut metal to remove a sharp burr and stiffen the edge; hems also reduce corrosion at exposed cuts and prevent injury during handling.