NRCA Metal Shingle flashcards
NRCA Metal Shingle · Build recall with a focused review session.
31 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Galvalume coating designation
- AZ50 or AZ55 indicates the coating weight of aluminum-zinc alloy on steel coil. Higher numbers mean more metallic coating and better corrosion resistance, especially in coastal or industrial environments.
- PVDF finish
- Polyvinylidene fluoride coating, typically 70% PVDF (Kynar 500/Hylar 5000), used on architectural metal shingles for color retention and chalk resistance. It outperforms polyester in harsh sun and salt exposure.
- Minimum steel gauge
- Most metal shingles use 26-gauge (about 0.018 inch) to 24-gauge (about 0.024 inch) steel. Thinner panels dent easily and oil-can; always confirm the manufacturer's minimum for the specific profile.
- Clip-fastened system
- A metal shingle or panel system attached with concealed clips rather than fasteners through the panel face. Clips allow thermal movement and reduce visible fasteners, but clip spacing and engagement must match the listing.
- Galvanic corrosion
- Dissimilar metals in contact with moisture create a galvanic cell; the less noble metal corrodes. Copper and steel, or aluminum and steel, must be separated by a barrier or matched fasteners to prevent premature failure.
- Steep-slope fall protection trigger
- OSHA requires fall protection on roofs with slope greater than 4:12. Metal shingle roofs are steep-slope work, so guardrails, safety nets, or personal fall arrest systems are mandatory.
- PFAS anchorage strength
- Personal fall arrest anchorages must support at least 5,000 pounds per worker, or be designed by a qualified person with a safety factor of at least two. Inspect anchorage and connectors before each use.
- Total fall distance
- The sum of free fall, deceleration distance, harness stretch, and a safety margin, measured from the anchorage to the lower level. It must not exceed available clearance or the worker hits the ground.
- Roof jack platform
- A bracket-and-plank system hooked over the ridge or nailed to the deck to create a level working platform on steep slopes. It reduces slip risk and supports workers and materials during installation.
- Overhead line clearance
- Metal roofing conducts electricity. OSHA requires at least 10 feet of clearance from energized overhead lines for workers and conductive equipment; use non-conductive ladders and keep panels away from lines.
- Ice barrier membrane
- A self-adhering waterproof membrane installed at eaves from the edge to at least 24 inches inside the exterior wall line, and in valleys, to prevent ice-dam backup. Required by IRC R905.1.2.
- Underlayment overlap
- Side laps are commonly 4 to 6 inches and end laps 6 to 12 inches, with upper courses lapping over lower courses. Manufacturer instructions govern; laps shed water downhill and must not be reversed.
- Deck fastener flushness
- Nail and screw heads must be flush or slightly countersunk, never protruding. Protrusions telegraph through underlayment and metal, causing oil-canning, wear, and leaks over time.
- Valley underlayment strip
- A minimum 36-inch-wide strip of underlayment centered in the valley, 18 inches up each roof plane, provides extra protection. Some manufacturers require a W-rolled or metal valley lining instead.
- Solid sheathing requirement
- Most metal shingles require solid decking, often 15/32-inch OSB or nominal 1-inch boards, with gaps no wider than 1/8 inch. Spaced sheathing is allowed only where the product listing permits it.
- Level line at eave
- A chalk line struck level at the eave sets the first course height. Courses are laid to level lines, not to the deck edge, because deck edges and fascia are rarely square to the roof.
- Course exposure calculation
- Divide the slope length by the manufacturer's published exposure to get the number of courses. Adjust the eave starter or top course so no narrow partial course lands at the ridge.
- Fastening zone
- The manufacturer-designated area on each shingle, usually the upper flange or lock, where fasteners are placed. Fasteners through the exposed face or water channel cause leaks and void warranties.
- Overdriven fastener
- A fastener driven too deep, crushing the washer and deforming the panel. It creates a leak path and stress point; the washer should be snug, not flattened past its designed compression.
- Starter course
- The first row of shingles or the manufacturer's starter strip at the eave. It sets the height and level of all subsequent courses and must be installed level around the entire perimeter.
- Open valley pan
- A metal valley pan, typically 24 inches wide (12 inches each side), installed under the shingles with the center exposed. Fasten only at the upper edge so the pan can move thermally.
- Step flashing
- L-shaped flashing installed one piece per course at sidewalls, interleaved with shingles so each piece laps the shingle below and is covered by the shingle above. Sealant alone is not a flashing.
- Headwall cricket
- A small peaked diverter installed on the uphill side of a wide headwall or chimney to shed water around it. Required when the wall width exceeds the manufacturer's threshold, commonly 30 inches.
- Drip edge placement
- Eave drip edge goes under the underlayment at the eave; rake edge metal goes over the underlayment at the rake, unless the manufacturer specifies otherwise. The drip leg must clear the fascia.
- Pipe boot flashing
- A manufactured flashing with a flexible collar matched to the pipe diameter, set in approved sealant with the upper flange lapped by the shingle course above. Large pipes need a flashed curb.
- Balanced ventilation ratio
- Provide roughly equal net free area at intake (soffit) and exhaust (ridge), commonly 1 square foot per 150 square feet of attic floor, or 1:300 with a vapor retarder and balanced vents.
- Thermal expansion coefficient
- Steel expands about 6.5×10⁻⁶ per °F and aluminum about 13×10⁻⁶ per °F. A 20-foot steel panel moves roughly 1/8 to 1/4 inch over a 100°F swing.
- Slotted fastener hole
- An elongated hole in a panel or clip that lets the panel slide as it expands and contracts. It prevents buckling and fastener shear in direct-fastened systems where movement must be accommodated.
- Cold-deck condensation
- Moisture in warm attic air condenses on the cold underside of metal roofing. A vapor retarder on the warm side plus ventilation above the insulation keeps the deck and panel dry.
- Wind uplift listing
- A product's rated resistance to wind pressure, documented by agencies such as Miami-Dade NOA or Texas Department of Insurance. Installation must match the listed fastener pattern and spacing exactly.
- IRC metal roof section
- IRC Chapter 9, Section R905.10 governs metal roofing installation, and R905.1.2 covers ice barriers. Manufacturer instructions apply where they are more restrictive than the code minimum.