Oklahoma Roofing Contractor Commercial Endorsement

General Roofing Knowledge Study Brief

Key Concepts

Slope Classifications - Low-slope roofs: Less than 2:12 pitch (rise:run). Require membrane-type systems. - Steep-slope roofs: 2:12 or greater pitch. Permit shingles, tile, slate, and similar products. - The 2:12 threshold is the critical dividing line for product and system selection under IBC Chapter 15.

Membrane Roof System Components (Low-Slope) Three primary layers in sequence: 1. Insulation – Thermal control layer; typically rigid board (polyiso, EPS, XPS) 2. Roof membrane – Weatherproofing layer (TPO, EPDM, PVC, modified bitumen, BUR) 3. Surfacing – Protective top layer (gravel ballast, coatings, cap sheet); required for BUR to protect against UV and mechanical damage

Steep-Slope Covering Types - Asphalt shingles – Most common; require minimum 2:12 slope (with special underlayment) up to standard 4:12 application - Clay and concrete tile – Minimum 2½:12 to 4:12 depending on tile type; heavy dead load consideration - Slate – Minimum 4:12; natural material, long service life - Metal shingles – Minimum 3:12 - Wood shakes – Minimum 3:12; shingles minimum 3:12 (some applications 2:12 with underlayment)

Key Concepts

Membrane Types & Attachment Methods

• BUR (Built-Up Roofing): Multiple plies of bitumen-saturated felt mopped with hot asphalt or cold adhesive. Aggregate surfaced or cap sheet finished. Fully adhered system.
• Polymer-Modified Bitumen: SBS (rubberized, cold/torch applied, flexible in low temps) vs. APP (plastomeric, torch applied, UV resistant). Applied in one or two plies; can be self-adhered, cold-applied, or torch-fused.
• EPDM: Thermoset single-ply. Attached by fully adhered, mechanically fastened, or ballasted method. Seams lapped and bonded with tape or adhesive. Ballasted systems require minimum ½ inch slope.
• Thermoplastic (TPO/PVC): Seams heat-welded (hot air). TPO is polyolefin-based; PVC is more chemical-resistant. Mechanically fastened, adhered, or ballasted. PVC not compatible with EPS insulation.
• Liquid-Applied: Fluid coatings (polyurethane, silicone, acrylic) applied by spray, roller, or squeegee. Seamless membrane — critical for complex geometries. Require base coat + top coat; minimum mil thickness per manufacturer.
• SPF (Spray Polyurethane Foam): Provides insulation and waterproofing in one application. Must be protected with UV-resistant coating (silicone most common). Applied to minimum ½:12 slope surfaces.

Oklahoma Roofing Contractor Commercial Endorsement — Study Brief

Key Concepts

Metal Types and Properties

• Aluminum: Lightweight, corrosion-resistant, but soft — requires thicker gauge in high-traffic areas; incompatible with concrete/mortar (alkaline attack)
• Copper: Long lifespan (100+ years), develops protective patina; minimum 16 oz/sq ft for standing seam; highly reactive — isolate from steel, aluminum, and zinc
• Galvanized Steel: Carbon steel coated with zinc; G-90 coating (0.90 oz/sq ft zinc) is standard minimum for roofing; can rust at cut edges
• Galvalume: Steel coated with aluminum-zinc alloy (55% Al, 43.4% Zn); superior corrosion resistance over galvanized, especially at cut edges; do not use with copper or treated lumber containing CCA
• Stainless Steel: Type 304 (general use) or Type 316 (coastal/chemical environments); most expensive, highest corrosion resistance
• Zinc: Self-healing patina (zinc carbonate); minimum 0.027" thick for roofing; cold-temperature brittleness is a concern

Panel System Classifications

• Architectural metal panels: Designed for use over a solid substrate (deck); rely on underlayment for waterproofing; not intended for structural spanning
• Structural metal panels: Can span between purlins without a solid deck; self-supporting; typically used on low-slope commercial roofs

Moisture and Energy Control — Study Brief

Key Concepts

Thermal Resistance Values

• R-value: Resistance to heat flow. Higher = better insulation. R = 1/C
• U-factor: Rate of heat transfer through an assembly (BTU/hr·ft²·°F). Lower = better. U = 1/R-total
• k-value (thermal conductivity): Heat flow through 1 inch of a material per unit area per degree of temperature difference. Lower k = better insulator
• C-factor (thermal conductance): Heat flow per unit area per degree. C = k ÷ thickness. Used for specific thicknesses of material

Rigid Board Insulation Types for Commercial Roofing

Select based on: climate zone, slope, fire rating requirements, and moisture exposure.

Key Concepts

Re-Cover vs. Tear-Off Decision

• Re-cover (adding a new roof system over existing) is permitted when the existing roof is structurally sound and moisture-free. It avoids landfill costs and speeds installation.
• IBC limits re-covers to one additional layer over the existing roof system. If a second re-cover is proposed, full tear-off is required.
• Tear-off is mandatory when: wet insulation is present, the deck is structurally compromised, the existing system has two or more roofing layers already, or code compliance cannot be achieved otherwise.

Roof Inspection Procedure

Inspect in this sequence: surface condition → flashings → penetrations → drainage → moisture. Document all findings before recommending action. - Check flashings at walls, curbs, and edges for separation, corrosion, or improper termination. - Evaluate drainage for ponding evidence, blocked drains, and slope adequacy. - Assess penetrations (pipes, HVAC curbs, conduit) for sealant failure or displaced counterflashing.

Moisture Evaluation

• Nondestructive methods: infrared (IR) thermography (detects wet insulation by thermal mass difference), nuclear back-scatter, capacitance meters.
• Core cut analysis: physical removal of a small plug of the roof assembly to visually confirm wet or degraded insulation, assess number of existing layers, identify materials (including ACM). Always patch cores properly.
• A minimum of one core cut per 10,000 sq ft is a common industry standard; more in suspect areas.

Key Concepts

Fall Protection (29 CFR 1926 Subpart M)

• Low-slope roofs (≤4:12 pitch): Workers must be protected at 6 feet above a lower level using guardrails, safety nets, or personal fall arrest systems (PFAS). Warning line systems + safety monitoring systems are an option.
• Steep-slope roofs (>4:12 pitch): Require guardrails, PFAS, or safety nets. Warning line systems alone are not permitted on steep slopes.
• Fall protection is required for all roofing work at 6 feet or more above a lower level (§1926.502).

Personal Fall Arrest Systems (PFAS)

• Components: Body harness (full-body only — body belts prohibited for fall arrest), lanyard, deceleration device, anchor point.
• Anchor strength: Must support 5,000 lbs per employee or be designed with a safety factor of 2 under supervision of a qualified person.
• Free-fall limit: Maximum 6 feet of free fall; arresting force must not exceed 1,800 lbs on the worker.
• Deceleration distance: Maximum 3.5 feet.
• After a fall arrest event, the harness must be removed from service and inspected before reuse.