Class Code 5479
Insulation Work
Class Code 5479 covers insulation work in California — installation of thermal and acoustic insulation on buildings, ducts, piping and equipment. The WCIRB-approved pure premium rate for 9/1/2026 is $5.419 per $100 of payroll, a base measure of expected loss costs for these operations.
What Class Code 5479 Covers
This classification applies to contractors and crews who install, cut, fit and secure insulation materials used for thermal, acoustic or fire-resistive purposes. Typical operations include installing batts and rolls (fiberglass, mineral wool), blowing loose-fill cellulose, applying and trimming spray polyurethane foam, wrapping and lagging pipe insulation, and insulating HVAC ductwork and equipment. Work on attics, crawlspaces, mechanical rooms and exterior walls is covered when the employer’s workers perform the insulation work. Note: specialized asbestos or lead abatement, demolition with regulated materials, and licensed hazardous-material removal are generally excluded and require separate licensing and classification.
Who It Applies To
- Residential and commercial insulation contractors (batt, blown, foam)
- Mechanical insulation crews insulating pipes, boilers and ductwork
- HVAC subcontractors performing duct and equipment insulation
- Weatherization and energy retrofit companies installing attic and wall insulation
- General contractors or subcontractors whose workforce performs routine insulation installation
Common Job Duties
- Measuring, cutting and fitting batts, rolls and rigid insulation
- Blowing loose-fill insulation into attics and wall cavities using blowers
- Applying, shaping and trimming spray polyurethane foam
- Wrapping and securing pipe, valve and equipment insulation (lagging)
- Working from ladders, scaffolds and in confined attic and crawlspace access
- Sealing air barriers, installing vapor retarders and fastening insulation to framing
Common Injury Risks
Understanding the $5.419 Rate
The pure premium rate of $5.419 per $100 payroll is the WCIRB’s loss-cost estimate for this class; it represents expected claim costs before insurer expenses and adjustments. To calculate base premium, insurers multiply the rate by the employer’s payroll for class 5479 divided by 100; the final premium is then adjusted by the employer’s experience modification, insurer loss-cost multipliers, policy-level credits/discounts or debits, and state assessments. Accurate class coding, payroll reporting and safety programs that reduce claims frequency/severity are primary ways employers can lower their ultimate premium.
Cal/OSHA Compliance Requirements
Insulation work in California is subject to multiple Cal/OSHA requirements: written respiratory protection programs and medical clearance/fit-testing when workers may inhale dust, fibers or isocyanates; hazard communication for insulation materials, adhesives and solvents; fall protection and ladder/scaffold safety for elevated work; and heat illness prevention for crews working in attics or roof areas. Work involving suspected asbestos or lead requires immediate exclusion from ordinary insulation classification and must follow Cal/OSHA abatement rules and licensed contractor requirements.
How Key HR Helps Employers Under Class Code 5479
A PEO like Key HR helps employers in class 5479 by centralizing workers' comp administration, managing claims to control loss development, and providing targeted loss-control services such as respirator fit tests, fall-protection training, and written program templates. Key HR also assists with accurate payroll classification, audit support, return-to-work coordination and access to safety training resources that can reduce experience modification and overall insurance cost.
Get a QuoteFrequently Asked Questions
Does class 5479 include both pipe and duct insulation?
Yes. Class 5479 covers installation of thermal and acoustic insulation on building elements, including ductwork and piping, when performed by the employer’s insulation crews. Specialty mechanical insulation for industrial boilers may require separate classification if the operations are substantially different.
Is spray polyurethane foam (SPF) installation under 5479?
SPF installation is commonly coded to 5479 when the same insulation contractor applies the foam as part of normal insulation services. Because SPF involves isocyanates and chemical exposures, employers must implement respirator programs, training and controls — and document operations carefully for proper classification and underwriting.
What activities would trigger a different classification from 5479?
Abatement or demolition involving regulated asbestos-containing materials, lead removal, industrial insulation on specialized high-temperature or pressure systems, and licensed hazardous-material removal are typically excluded from 5479 and require separate classification, credentialing and insurance handling.
Quick Facts
- Class Code
- 5479
- Classification
- Insulation Work
- Pure Premium Rate
- $5.419 / $100 payroll
- Effective Date
- September 1, 2026
- Source
- WCIRB Approved Filing
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