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IICRC S770 Fire and Smoke Damage Restoration: Residue Types, Cleaning Methods, and Insurance Billing
Fire damage cleaning is technically the most complex specialty in the BSC toolkit. Unlike water damage — where the drying goal is objective and measurable — fire and smoke remediation requires identifying invisible gas-phase contamination, matching cleaning chemistry to four distinct residue types, and managing odor elimination through chemistry and equipment rather than purely physical cleaning. The IICRC S770 Standard for Professional Fire and Smoke Damage Restoration is the technical framework that governs scope, documentation, and insurance reimbursement across all of these challenges.
This guide covers the S770 residue classification system, surface-specific cleaning protocols, odor elimination methods, HVAC decontamination requirements, and the documentation format that maximizes insurance billing.
S770: What It Is and Who Needs It
The IICRC S770 is published by the Institute of Inspection, Cleaning and Restoration Certification as the industry standard for fire and smoke damage restoration. (IICRC S770) It is the companion standard to S500 (water damage) and S520 (mold remediation), completing the IICRC's coverage of the major property damage restoration categories.
The US fire damage restoration market generates approximately $8.5 billion annually in insured claims (Insurance Information Institute data). As with water damage, the overwhelming majority of fire restoration revenue flows through property and casualty insurance claims — and Xactimate, the industry estimating platform, prices fire scope line items directly aligned with S770 categories. Contractors who work outside the S770 framework consistently under-bill insurance claims by 25–40% compared to certified competitors.
The S770 FSRT (Fire and Smoke Restoration Technician) certification is the entry point for this market. One-day course plus written exam at an IICRC-approved school. (IICRC certifications)
S770 Residue Classification: The Core Technical Foundation
The single most important technical decision in fire cleaning is residue type identification. The wrong cleaning method on the wrong residue type either fails to clean (smearing instead of removing) or damages the underlying surface. S770 defines four primary residue types:
Type 1: Dry Smoke Residue
Origin: Fast-burning, high-temperature fires involving paper, wood, and natural fibers. Physical characteristics: Powdery, ashy, gray-black; does not smear easily when dry; relatively low odor compared to wet smoke. Where found: Paper fires, cardboard, natural wood furniture, wood trim.
Cleaning approach: Dry chemical sponge (Chem-Sponge or equivalent) FIRST before any wet cleaning. The dry sponge lifts dry smoke particles mechanically. Applying wet chemicals to dry smoke first smears the soot into the surface, dramatically increasing cleaning difficulty and potentially causing permanent staining.
After dry sponge: Light dry alkaline cleaner applied in single directional wipes (not circular — circular motions redistribute soot).
Type 2: Wet Smoke Residue
Origin: Slow-burning, low-temperature fires — smoldering fires, partially extinguished fires, synthetic materials (rubber, plastic, foam). Physical characteristics: Sticky, tacky, web-like or streaky deposits; very strong, pungent odor; smears when touched. Where found: Rubber burning, electrical fires (wire insulation), plastic furniture, foam cushions.
Critical: This is the residue most likely to damage surfaces through mishandling. The sticky, partially polymerized carbon compounds in wet smoke will smear into porous surfaces (drywall, wood) if scrubbed with water before chemical breakdown.
Cleaning approach: Solvent-based or strong alkaline chemical cleaner applied in controlled dwell time — no mechanical agitation until chemical has penetrated. Chemical sponge after initial treatment. Multiple passes required on porous surfaces.
Type 3: Protein Residue
Origin: Kitchen fires, food combustion — proteins and lipids burning at medium-to-high temperatures. Physical characteristics: Appears as a near-invisible, yellowish-brown varnish-like film; very strong odor disproportionate to visual appearance (the "greasy kitchen fire smell"). Where found: Restaurant kitchen fires, residential kitchen grease fires, any cooking environment.
This is the residue most underestimated in scope. The film is nearly invisible — walls and ceilings in a kitchen fire may appear clean to an untrained eye while carrying significant protein contamination that will generate odor for months.
Cleaning approach: Enzyme-based or protease cleaner specifically formulated for protein breakdown. Applied with dwell time; light mechanical agitation; neutralizing rinse. May require 3–4 cleaning passes on heavily contaminated surfaces.
Type 4: Fuel Oil Soot (Puffback)
Origin: Furnace malfunction (delayed ignition or oil supply failure) causing combustion gases to be expelled backward through the heating system — "puffback." Physical characteristics: Heavy, wet, oily black soot that penetrates deeply into porous surfaces; strong petroleum odor. Where found: Near furnace/boiler; soot enters through HVAC registers and distributes through entire building.
This is typically the most expensive residential fire cleaning scenario — puffback affects every room with HVAC registers, requiring full-building cleaning of walls, ceilings, contents, and ductwork.
Cleaning approach: Commercial degreaser (alkaline, pH 11–12) for surface cleaning; heavy wet sponge; multiple passes. HVAC system must be decontaminated completely — running the HVAC before duct cleaning redistributes soot throughout the cleaned building.
Odor Elimination: Beyond Surface Cleaning
Smoke odor persists long after visible soot is removed because gas-phase contamination — volatile organic compounds (VOCs), carbonyl compounds, and polycyclic aromatic hydrocarbons (PAHs) — penetrates deep into porous building materials: drywall, wood framing, upholstery, and carpet. Surface cleaning removes the visible residue but does not eliminate absorbed gas-phase contamination.
S770 covers four primary odor elimination approaches:
Thermal Fogging
Heated petroleum-based deodorizer creates a fog that physically penetrates materials — entering the same micropores the smoke occupied. Effective for deep deodorization in structures with significant smoke penetration.
Requirements: Must run in vacated spaces (petroleum fog is a respiratory irritant at treatment concentrations); post-treatment ventilation for 4+ hours before re-occupancy. Not for electronics-sensitive environments.
Hydroxyl Generation
Hydroxyl generators produce hydroxyl radicals (OH•) through UV photolysis — the same atmospheric chemistry that naturally breaks down VOCs. These radicals oxidize odor-causing molecules chemically.
Advantages over ozone: Can operate with some contents in place; considered safer for electronics; no re-occupancy restriction during treatment at normal concentrations. Limitation: Slower than ozone or thermal fogging; typically runs 24–72 hours for full penetration effect.
Ozone Treatment
O₃ is a highly effective oxidizing agent that chemically destroys odor molecules. Ozone generators produce high concentrations of O₃ that penetrate porous materials and eliminate VOCs.
Requirements: Ozone is toxic to humans and pets at treatment concentrations — spaces must be completely vacated. Minimum 2–4 hours of post-treatment ventilation before re-entry. Not appropriate for buildings with electronics (ozone corrodes metal contacts), rubber components, or perishable materials.
HEPA Air Scrubbing
HEPA air scrubbers continuously filter airborne soot particles during and after cleaning. They reduce re-soiling of cleaned surfaces and lower airborne particulate load, but do not address gas-phase odor alone. Required throughout all S770 cleaning activities.
Typical deployment: 1 air scrubber per 500–800 sq ft of affected space; run continuously.
HVAC System Decontamination
Fire soot — especially from puffback scenarios — distributes through the HVAC system and requires full duct cleaning before the system is operated post-fire. Running a contaminated HVAC system redeposits soot throughout the entire structure, undoing all surface cleaning work.
Required steps (NADCA ACR 2021 aligned):
- Inspect supply and return ducts via video camera before any operation
- Replace all air filters and A-coil media
- If visible soot contamination: full NADCA-standard duct cleaning under negative pressure
- Clean evaporator coil if contaminated
- Verify coil cleanliness before system operation
- Document inspection and cleaning for insurance billing
HVAC decontamination is a frequently missed or under-billed line item in fire damage estimates. It requires either in-house NADCA capability or a certified subcontractor relationship.
Surface-Specific Protocols
Hard Surfaces (Walls, Ceilings, Counters)
- Residue identification before any chemical application
- Dry sponge all surfaces before wet chemical (for dry smoke scenarios)
- Apply chemical top-to-bottom, single directional strokes
- Neutralizing rinse with clean water; dry immediately
Contents (Furniture, Textiles, Electronics)
- Separate into: clean in place, pack-out for off-site cleaning, or non-salvageable
- Contents cleaning (textiles, upholstery) is typically billed separately as a contents-specific scope
- Electronics: photo-document all affected electronics; do not power on smoke-affected electronics without professional inspection
Structural Materials
- Heavily saturated porous materials (carpet, insulation, drywall absorbing Cat 3 or wet smoke) may require removal
- Document removal scope separately in Xactimate
- Coordinate removal with reconstruction GC
Typical insurance claim range for commercial fire damage cleaning scope (structure only, not reconstruction) in a mid-size commercial building. S770-certified contractors billing through Xactimate with complete documentation consistently collect 25–40% more per claim than uncertified contractors submitting lump-sum bids. Source: IICRC contractor member data / Verisk Xactimate pricing benchmarks
Frequently Asked Questions
Is soot and smoke cleanup considered restoration or remediation?
Whether material leaves the building is what decides the label. Cleaning and deodorizing surfaces affected by fire or smoke, with structural materials left in place, is restoration cleaning. Once contaminated materials are being removed, the work reads as remediation, and mold or biohazard remediation typically requires additional licensing in states that maintain mold contractor registration requirements. Scope that honestly before you quote, because the licensing question follows the demolition, not the odor.
Why do carriers push IICRC certification on fire claims?
Carrier vendor lists are the gatekeeper here, not the statute book. Most states do not make certification a legal requirement, yet carriers generally require their preferred vendor contractors to hold IICRC WRT (Water Restoration Technician) or similar certifications before they will add a shop. An uncertified contractor is simply excluded from those programs, so the credential works less like a diploma and more like an entry pass to insurance restoration work.
How do fire and smoke jobs find their way to a restoration company?
Almost none of this work arrives by cold call. Independent insurance agents hand their clients to preferred vendors they already trust, and carrier preferred vendor programs feed jobs to contractors who have completed that carrier's own application and vetting. Referral networks among plumbers, HVAC contractors, and other emergency restoration firms move overflow work sideways, and emergency response boards cover calls that come in hot.
A fire left the structure wet — what does the drying side require?
When a fire loss also involves wet structure, the drying portion answers to S500's numbers. Standard Dry means wood at or below 19% moisture content and drywall at or below 17%, along with an equilibrium moisture content comparable to adjacent unaffected materials. Temperature, relative humidity, and specific humidity readings show whether drying is moving, and those daily readings have to be documented. Soot and odor work can run alongside, but the drying targets are what the file has to prove.
Documentation for Insurance Billing
Complete S770 documentation for each project:
- Scope diagram with room measurements and affected surface areas
- Residue type identification per room (photos + written assessment)
- Equipment inventory: HEPA scrubbers (serial, date placed, daily hours), odor treatment equipment
- Cleaning pass documentation per surface (before/after photos per room)
- Contents inventory with pre/post photos
- HVAC inspection report
- Odor treatment log (equipment, concentration, run-time, re-occupancy clearance)
- Post-remediation air quality test result (required by some insurers)
Insurance Billing for Restoration Work
Restoration cleaning companies frequently work as the on-site contractor for insurance claims. Understanding the insurance billing process is essential for cash flow and contract compliance.
Xactimate pricing software: Most property insurance adjusters use Xactimate (Verisk) to estimate restoration costs. Xactimate line items reference regional pricing databases updated monthly. Restoration contractors who bill outside Xactimate line items face disputes. Train your estimators on Xactimate or use a public adjuster/contractor consultant for large claims.
Mitigation vs. Remediation billing: Insurance adjusters distinguish between emergency mitigation (stopping the damage) and remediation (restoring the structure). These are billed separately; get separate work authorizations for each phase.
Photo documentation for billing defense: For every insurance restoration job, photograph pre-work conditions, moisture readings (with psychrometer or moisture meter readings logged), equipment placement, and post-work conditions. Insurance auditors can challenge any line item not supported by documentation.