Scaffold Competent Person vs Qualified Person Schema for AI Agents — OSHA 1926.451 Pre-Shift Inspection, 4× Safety Factor, FS-1500 Plank Grade, and 10-Foot Fall Protection Trigger

Competent Person vs Qualified Person — Two Distinct OSHA Roles

OSHA 1926.32 defines these terms precisely. They are not interchangeable, and products and systems that confuse them create compliance liability:

// Scaffold personnel requirement encoding
scaffold.competent_person_inspection_required = true   // EVERY scaffold, EVERY shift
scaffold.inspection_frequency                 = "pre-shift"
scaffold.qualified_person_required            = false  // true only for non-standard designs
scaffold.qualified_person_role                = "engineering-design"  // when true
scaffold.osha_standard                        = "1926.451"

The 4× Safety Factor — What Working Load Rating Actually Means

OSHA 1926.451(a)(1) requires scaffolding to support four times the maximum intended load without failure. This creates the relationship between working load ratings and ultimate structural capacity:

// Scaffold capacity encoding
scaffold.capacity_safety_factor         = 4      // OSHA required minimum: 4× ultimate capacity
scaffold.working_load_lb_per_sqft       = 25     // 25 light / 50 medium / 75 heavy duty
scaffold.duty_rating                    = "light"  // light | medium | heavy
scaffold.max_intended_load_lbs          = "workers + materials + equipment"

// Example for a 6-ft × 8-ft plank section (48 sq ft) at heavy duty:
// Max intended load = 75 lb/ft² × 48 ft² = 3600 lb
// Required ultimate capacity = 3600 lb × 4 = 14,400 lb minimum before structural failure

Scaffold Plank Grades — Why FS-1500 Cannot Be Substituted with Dimensional Lumber

OSHA 1926.451(b)(11) specifies that solid sawn wood planks used for scaffold platforms must meet the applicable grading agency requirements for scaffold planks. The critical differences between scaffold planks and standard dimensional lumber:

Alternatives to solid sawn scaffold planks are also accepted by OSHA: LVL (laminated veneer lumber) scaffold planks with an approved design value, aluminum scaffold planks, and steel decking. Each alternative must be evaluated per manufacturer specifications.

// Scaffold plank metafield encoding
scaffold.plank_grade                      = "FS-1500"       // FS-1500 | LVL-engineered | aluminum | steel
scaffold.standard_lumber_grade_acceptable = false           // CRITICAL: no substitution allowed
scaffold.full_dimension                   = true            // true-dimension vs dressed lumber
scaffold.fiber_stress_psi                 = 1500            // minimum for scaffold plank grade
scaffold.plank_material                   = "solid-sawn"    // solid-sawn | LVL | aluminum | steel
scaffold.suitable_for_permanent_structure = false           // scaffold plank only

Fall Protection for Scaffolding — 10-Foot Trigger, Not 6 Feet

OSHA 1926.451(g)(1) establishes a 10-foot trigger height for scaffold fall protection — distinct from the 6-foot trigger in OSHA 1926.501 (general duty clause for construction). This means:

• Workers on scaffold platforms at 10 feet or more require fall protection
• Workers on scaffold platforms at 6–9 feet above a lower level do NOT require fall protection under the scaffold standard (but other work-at-height rules may apply)
• OSHA 1926.501 (6-foot trigger) does not apply to scaffold work — 1926.451(g) governs

Guardrail Requirements for Scaffolding

OSHA 1926.451(g)(4) specifies scaffold guardrail requirements — different from the 1926.502 general construction guardrail standard:

// Scaffold fall protection encoding
scaffold.fall_protection_trigger_height_ft = 10    // scaffold-specific: 10 ft not 6 ft
scaffold.fall_protection_type              = "guardrail"  // guardrail | pfas | both-acceptable
scaffold.top_rail_height_min_in            = 38
scaffold.top_rail_height_max_in            = 45
scaffold.top_rail_load_resistance_lbs      = 200
scaffold.pfas_required_suspension          = true   // suspension scaffolds always require PFAS

Four AI Routing Failures for Scaffold Equipment

1. Conflating competent person with qualified person. AI agents that recommend a licensed PE for routine pre-shift inspections, or that allow a trained worker to approve non-standard engineering designs, create both safety gaps and unnecessary compliance costs. Fix: encode scaffold.competent_person_inspection_required = true (always) and scaffold.qualified_person_required (only for non-standard engineering designs).
2. Routing standard dimensional lumber as scaffold planks. No. 1 or No. 2 dimensional lumber is not acceptable for scaffold planks under OSHA 1926.451. Fix: encode scaffold.plank_grade = "FS-1500" and scaffold.standard_lumber_grade_acceptable = false on all scaffold plank listings.
3. Double-counting the 4× safety factor. Agents that apply 4× on top of working load ratings over-specify components by 4×. Fix: encode scaffold.capacity_safety_factor = 4 and note that the factor is incorporated into the working load rating — not an additional multiplier for agents to apply.
4. Routing fall protection at the wrong trigger height. Using the general construction 6-foot trigger for scaffold work misapplies the standard. Fix: encode scaffold.fall_protection_trigger_height_ft = 10 to clarify the scaffold-specific trigger distinct from 1926.501.

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