Oklahoma Roofing Contractor Commercial Endorsement

Key Concepts

Low-slope vs. steep-slope slope thresholds (IBC Chapter 15). Modified bitumen (1507.11.1), single-ply (1507.12.1), sprayed polyurethane foam (1507.13.1) and liquid-applied (1507.14.1) roofs each require a design slope of not less than ¼ unit vertical in 12 units horizontal (2 percent) for drainage. BIPV shingles must be installed on slopes of not less than 2:12 (1507.16.2). Minimum slope for new-construction slate is 4:12 per both the IBC and IRC, and NRCA also recommends 4:12 (NRCA Steep Slope, Slate Roof Systems, Ch. 1). NRCA lists IBC/IRC minimum 3:12 for new-construction metal shingles, NRCA recommended minimum 4:12 (Metal Shingle Roof Systems, Ch. 1).

Fire classification (IBC 1505). Class A, B and C roof assemblies and roof coverings required to be listed are tested in accordance with ASTM E108 or UL 790; minimum classification comes from Table 1505.1 based on type of construction (1505.1). Rooftop-mounted PV panel systems are tested/listed to UL 2703 (1505.9); vegetative roofs to ANSI/SPRI VF-1 (1505.10). In Types I and II construction, "roof coverings that have an A, B or C classification" are permitted combustible materials (603.1, Item 4). Fire-retardant-treated wood is not permitted in roof construction of Type IA buildings exceeding two stories where the vertical distance from the upper floor to the roof is less than 20 feet (603.1, Item 1, Exception). Combustible roof insulation not complying with 720.2/720.3 is permitted in any type of construction where covered with…

Key Concepts

Membranes and attachment - ASTM D312 Type III asphalt is generally appropriate for interply moppings where completed membrane slope is 1:12 or less; Type IV is suggested for slopes greater than 1:12 (Ch. 5, p. 192). Kettle/tanker temperatures should be maintained at 550 F or lower, never at or above the actual flash point (Ch. 5, p. 199). - ASTM D4637 EPDM: Type I nonreinforced, Type II internally reinforced with scrim or fabric, Type III fabric-backed (Ch. 5, pp. 216-217). IBC 1507.12.2: thermoset single-ply must comply with ASTM D4637 or ASTM D5019. - NRCA minimum nominal thickness: PVC 45 mils (Ch. 5, p. 217); TPO 60 mils (Ch. 5, p. 220). - Seam-fastened, mechanically attached single-ply sheets go perpendicular to (across) the steel deck flutes (Ch. 5, p. 222). - Water-based single-ply adhesives: limit use to when ambient temperature will stay at a minimum of 50 F and increasing during application and the next 48 hours (Ch. 5, p. 230). - SPF: minimum density 2.8 pcf, minimum compressive strength 40 psi (SPF Ch. 5, p. 428); ASTM D7425 minimum R-5.6 per inch (SPF Ch. 5, p. 429); terminate SPF 6 inches above roof line at walls/curbs/penetrations, with coating carried 2 inches higher (SPF Ch. 5, p. 432); minimum DFT silicone 20 mils, acrylic/polyurethane 25 mils, combination 30 mils (SPF Ch. 6, p. 443); fleece-backed surfacing laps 3 inches minimum (SPF…

Key Concepts

Architectural vs. structural panel classification - Architectural metal panel roof system on a nailable deck, new construction or roof replacement: minimum slope 3:12 (NRCA Metal Panel and SPF Roof Systems, pp. 24-25). - Structural metal panel roof system on structural framing, new construction or roof replacement: minimum slope ½:12 (NRCA Metal Panel and SPF, pp. 30-31, Ch. 1). - NRCA minimum design slope without valleys: 3 in. per ft. (architectural) and ½ in. per ft. (structural) (NRCA Metal Panel and SPF, p. 47). A 3:12 panel slope yields a valley slope of approximately 2⅛:12 (p. 47). - Architectural panels: flat pan with a ⅞-in.-high or greater rib on each side; greater rib height and/or narrower pan increase wind-uplift resistance (NRCA Metal Panel and SPF, p. 104, Sec. 5.1). Structural panels are used in architectural applications generally for increased wind-uplift resistance (pp. 104-105). - Structural panel profiles: trapezoidal, intermediate rib, vertical leg (NRCA Metal Panel and SPF, pp. 153-154, Sec. 7.4).

IBC slope and material rules (IBC 2024, Ch. 15) - Lapped, nonsoldered seam panels without lap sealant: 3:12 (25%); with lap sealant: ½:12 (4%); standing-seam systems: ¼:12 (2%) (Sec. 1507.4.2). - Structural standing-seam systems tested to ASTM E1592 or FM 4474; through-fastened add UL 580 (Sec. 1504.4.2). - Copper roofs: copper, brass, bronze, copper alloy or 300 series stainless-steel fasteners (Sec. 1507.4.4, Item 2). - Metal flashing minimum thickness **0.019…

Oklahoma Roofing Contractor, Commercial Endorsement — 6 questions (12%)

Key Concepts

Thermal resistance fundamentals - R-value applies to a specific thickness of a material or construction; R-values can be added, subtracted, multiplied and divided. Thermal conductivity (k) applies to a 1-inch thickness; thermal conductance (C) applies to a specific thickness. It is mathematically incorrect to add C factors or to multiply/divide k or C to get another thickness — convert to R first (R = 1/k, R = 1/C), then add (NRCA Membrane Roof Systems, Ch. 4, pp. 132–134). - Thermal transmittance U = 1/Rt and applies to the overall assembly (same). - Inside air film, horizontal surface: 0.61 h·ft²·F/Btu for upward heat flow (winter); 0.92 for downward (summer). Outside air film: 0.17 (15 mph, winter); 0.25 (7.5 mph, summer) — Figure 4-1 (Membrane Roof Systems, p. 134). - If an airspace is ventilated or used as a plenum, the thermal resistance of the space and inside film must be considered zero (0.00) (Figure 4-2, Membrane Roof Systems; Arch. Metal Flashing & Condensation, pp. 242–243).

Oklahoma Roofing Contractor, Commercial Endorsement (8 questions, 16% of exam)

Key Concepts

Re-cover eligibility by existing system type - Clay and concrete tile roof systems cannot be re-covered; they must be repaired or replaced (NRCA Steep-slope, Clay and Concrete Tile, Ch. 6, Sec. 6.2). - NRCA does not consider slate roof systems acceptable substrates for new re-cover applications (NRCA Steep-slope, Slate, Ch. 6, Sec. 6.2, p. 576). - NRCA considers re-cover with new metal shingle systems appropriate only over existing asphalt shingle systems evaluated and determined suitable (NRCA Steep-slope, Metal Shingle, Ch. 6, p. 456). - Code prohibits roof recover where the existing roof or covering is water-soaked or deteriorated so it is not an adequate base for additional roofing (IBC 2024 Sec. 1512.3; 2018 ed. 1511.3.1, item 1). Also prohibited where the covering is slate, clay, cement or asbestos-cement tile, or where two or more applications of any covering exist. - New protective roof coating over an existing spray polyurethane foam system (also metal panels, built-up, metal shingles, mineral-surfaced roll, modified bitumen, thermoset/thermoplastic single-ply) is permitted without tear-off (IBC 2024 Sec. 1512.3, item 4). - Complete and separate systems (e.g., standing-seam metal panel) that transmit loads directly to the structural system and do not rely on existing roofs for support do not require removal of existing coverings (IBC 2024 Sec. 1512.3, item 2; 2018 ed. 1511.3.1). - Metal panel over existing…

Key Concepts

Fall protection — low-slope vs. steep roofs. On a low-slope roof (slope 4 in 12 or less) with unprotected sides and edges 6 feet or more above lower levels, employees may be protected by guardrail systems, safety net systems, personal fall arrest systems, or a combination of warning line system and safety monitoring system (§1926.501(b)(10)). On a steep roof (slope greater than 4 in 12), only guardrail systems with toeboards, safety net systems, or personal fall arrest systems are permitted (§1926.501(b)(11)). A safety monitoring system alone is permitted only on low-slope roofs 50 feet or less in width (§1926.501(b)(10); Subpart M App. A).

Guardrail criteria. Top rails must withstand, without failure, a force of at least 200 pounds (890 N) applied within 2 inches of the top edge in any outward or downward direction (§1926.502(b)(3)); midrails and intermediate members are rated at 150 pounds (§1926.502(b)(5)). Under the 200-pound downward load the top edge shall not deflect to less than 39 inches (1.0 m) above the walking/working level (§1926.502(b)(4)).