100+ Free NRCA Slate Practice Questions

The exam is two parts. The online eligibility exam (about 60 multiple-choice questions, English or Spanish, audio support) covers slate types and ASTM C406 grades, underlayments, layout (headlap, exposure, side lap), copper/stainless nailing, open metal valley construction, step and counter flashings, chimney details, ridge and hip work, repair techniques, OSHA fall protection (29 CFR 1926.501-503), and substrate preparation. After passing the online exam, candidates complete a 6-8 hour hands-on performance exam on a slate mockup, evaluated by a NRCA Qualified Assessor against Job Task Analysis (JTA) criteria.

Candidates must have at least 36 months of natural slate roof installation experience, including recent work in the past 12 months. An employer (or self-employed candidate) must validate this experience as part of the application. Candidates must also pass the online eligibility exam before scheduling the hands-on assessment with a Qualified Assessor. Working knowledge of The NRCA Roofing Manual: Steep-slope Roof Systems is expected.

ASTM C406 is the Standard Specification for Roofing Slate. It defines three grades based on water absorption (S1 0.25%, S2 0.36%, S3 0.45% maximum), modulus of rupture, and depth of softening (ASTM C217). Grade S1 has a documented service life of 75-200 years and is typical of Vermont, Buckingham (VA), and Peach Bottom (PA) sources. Grade S2 is 40-75 years and Grade S3 is 20-40 years. Reputable suppliers provide independent laboratory test reports for specific quarry runs.

Slate has a 75-200 year service life on Grade S1 material, but standard galvanized or bright steel fasteners corrode in 20-40 years. When fasteners fail before the slate, individual slates fall off (a condition called 'nail-sick') and the roof becomes a leak hazard despite sound slate. Copper or stainless steel nails match the slate's service life. They are also galvanically compatible with copper flashings, preventing accelerated corrosion at metal-to-metal contact points.

NRCA specifies a minimum 4:12 slope for natural slate with standard headlap. On slopes of 8:12 and steeper in moderate climates, the standard headlap is 3 inches. Between 4:12 and 8:12 the headlap increases to 4 inches. Below 4:12 slate is not recommended; a different roofing system should be used with a proper transition flashing. The exposure equals (slate length minus headlap) divided by 2 — so a 20-inch slate at 3-inch headlap exposes 8.5 inches.

NRCA strongly prefers open valleys with metal liners (typically 16-20 oz copper or stainless steel, 20-24 inches total width, with a center crimp). Ice-and-water shield is laid in the valley first, then the metal liner, then chalk lines snapped 4-6 inches from the valley centerline at the eave (widening toward the ridge in a 'splayed' valley). Slates are cut and installed to the chalk line. Long valleys use thermal expansion joints; sections are joined by hooked seams or soldered laps.