Fire and smoke damage restoration and odor removal field guide

Fire and smoke restoration, and why it is mostly a smoke job

Fire and smoke damage restoration is the work of stabilizing a building after a fire, cleaning the smoke and soot off every surface they reached, removing the odor at its source, and drying the water the fire department left behind. The fire is the event everyone pictures. The smoke is what you spend most of the job fighting.

A fire usually burns a contained area. The smoke does not stay there. It rides heat and air pressure through the whole structure, settles on cold surfaces in rooms that never saw a flame, and keeps working after the last ember is out. The residue it leaves is acidic, and acid does not wait. It corrodes metal, etches glass and finishes, yellows paint, and drives odor into every porous material it touches.

So the job is a race. Stabilize the structure, clean before the residue sets, match the method to the type of residue and the surface under it, get the odor out instead of covering it, and deal with the suppression water before it grows mold. Restoration crews that treat a fire like a cleaning job and not a clock job lose surfaces that could have been saved. For the water side of the loss, the structural drying guide carries the detail. For the air side, the air filtration guide covers the scrubbers and the particulate.

The smoke does more damage than the fire

Walk a fire loss and the burned room is rarely the worst of it. The flames consumed a closet, a stove, a section of wall. The smoke contaminated four floors. That is the part owners and new adjusters underestimate, and it is the part that drives the scope and the cost.

Smoke moves the way heat and pressure push it. It finds the gaps around doors, the chases, the return-air paths, and the cold exterior walls where it condenses and bonds. By the time the fire is out, soot has plated out on ceilings far from the burn, inside cabinets, behind switch plates, and on the cold side of glass. Open a drawer two rooms away and the film is already there.

The flames stop when the fire is suppressed. The residue does not stop. It keeps reacting with the surfaces it landed on, and the odor keeps loading into anything porous. That is the framing that should drive the whole response: you are not cleaning up after a fire that is over, you are racing a chemical process that is still running.

The residue is acidic and the clock is running

Smoke residue is acidic, and that single fact sets the pace of the entire job. Within hours, acidic soot starts reacting with the surfaces it settled on. Metal fixtures tarnish and corrode. Bare and plated metals pit. Glass and chrome etch. Painted surfaces and plastics yellow. Grout, marble, and finished wood stain. Left long enough, much of that damage stops being cleanable and becomes replacement.

Suppression makes it faster, not slower. When the fire department's water and the air's humidity combine with the soot, the residue gets more aggressive and corrosion accelerates. A common field figure is that surfaces start taking irreversible etching and staining within roughly 72 hours, and sooner on bare metal and high-gloss finishes. Treat that as a planning horizon, not a guarantee, because the real window depends on the residue type, the humidity, and the surface.

The practical move is to stabilize and start emergency cleaning fast. Get the corrosive residue off the vulnerable surfaces first, neutralize the acidity with the cleaning chemistry matched to the residue, and protect bare metal early. IICRC S700 frames smoke loss as time-sensitive for exactly this reason. The first crew on site should not be planning a full reconstruction. It should be stopping the corrosion.

The four residue types, and why the type drives everything

What burned and how hot it burned decide what residue you are cleaning, and the residue decides the method. Get this wrong and you either fail to clean a stubborn film or you damage a surface with a method it did not need. IICRC S700 organizes fire loss around residue characteristics, and the four types below are the field shorthand for it. Confirm the classification against the standard and the product manufacturer before you commit a chemistry.

Read the residue before you touch it. A near-invisible greasy film with a heavy odor is protein and behaves nothing like the dry powder off a paper fire, even though the powder looks worse. The table is the starting point, not the verdict, because real fires mix fuels and you often find more than one residue in the same building.

Wet smoke, the worst one to clean

Wet smoke comes from a slow, low-heat, smoldering fire, the kind that chokes a room with thick black smoke instead of burning hot and fast. Plastics, rubber, and synthetics are the usual fuels. The residue is smeary and sticky, it bonds hard to the surface, and the odor is heavy and stubborn.

This is the residue that punishes a careless wipe. Drag a wet rag across wet smoke and you smear it into a wider, thinner stain that has now worked deeper into the finish. It needs aggressive dry removal first to lift what will lift, then a heavy degreasing chemistry with dwell time to break the bonded film, and on some surfaces it needs mechanical or abrasive work the other residues never call for.

Budget more labor for wet smoke than the area suggests. A small smoldering fire in a synthetic-heavy room can leave a residue that takes longer to clean than a larger flash fire in a room full of paper and wood.

Dry smoke, the one that dusts off

Dry smoke is the product of a fast, hot fire in natural materials like paper, wood, and cotton. The residue is dry and powdery. It sits on the surface more than it bonds to it, and a lot of it lifts with dry methods alone.

That makes dry smoke the most forgiving residue, but only if you respect the order. The powder is loose, so dry sponging and HEPA vacuuming pull most of it before any liquid touches the wall. Wet it first and you turn a dust you could vacuum into a paste you have to scrub. Dry-clean, then follow with a lighter wet clean matched to the surface for whatever film remains.

Do not assume dry smoke means a light job everywhere. A hot fire still drives odor and fine particulate into porous materials and through the HVAC, so the cleaning may be quick while the deodorization and air decontamination are not.

Protein residue, the deceptive one

Protein residue is the one that fools people. It comes from kitchen and grease fires, where food and fat burn or scorch without much flame. There is often almost nothing to see. The walls and cabinets look clean, maybe a little yellowed or greasy, and the homeowner cannot understand why a restoration crew is even there.

Then you smell it. The odor is intense, it lingers, and it gets worse when the surfaces warm up. The film is a thin, greasy, near-invisible layer that has coated everything in the room and worked into porous surfaces, and it sticks. A standard all-purpose cleaner skates right over it.

Protein needs a degreaser and mechanical action, applied to surfaces that look like they do not need cleaning at all. Hedge the specific chemistry to IICRC S700 and the product manufacturer, because protein is exactly where the wrong cleaner does nothing and the wrong dwell time wastes a day. The deceptive part is the danger. Crews that clean what they can see and skip what they cannot get a callback when the odor comes back with the next warm day.

Safety and assessment before anyone enters

Nobody enters a fire structure until it is released and assessed. The fire department controls the scene first, and entry waits for their release. After that, the hazards are structural, electrical, and respiratory, and they are real even when the building looks calm. Charred framing can be load-compromised. Wiring and panels may be damaged. The air carries fine soot, combustion byproducts, and on some fires genuinely hazardous compounds.

Assessment is where the scope is born. Walk the building and map where the soot went, which is almost always farther than the burn. The soot map tells you which rooms are heavy, which are light, and where the smoke traveled through chases and the HVAC. Identify the residue type or types, the surfaces involved, the salvageable versus the lost, and the water from suppression. Note the cause if it is known, because an oil or chemical fire changes the hazard and may pull in an industrial hygienist and air testing.

This is also where you decide what gets stabilized today and what waits. Protect crews with the respiratory and PPE level the residue and the air call for, and hedge the structural and air-safety calls to a structural engineer and the AHJ when the damage is past a routine cleaning job. Skipping the assessment to start cleaning fast is how a crew works a building that is not safe to be in.

Secure the structure and board up

Once the building is released and assessed, secure it before anything else. A fire leaves a structure open. Broken windows, a hole in the roof, doors the fire department forced, all of it lets in weather, animals, and anyone who wants in. Every hour it stays open is more loss stacked on top of the fire.

Board up the broken openings, tarp the damaged roof sections, and close the building against rain and wind. Shut off the utilities that are compromised. This is emergency mitigation, and it serves two ends: it prevents further damage, and it shows the carrier that the loss was contained instead of left to spread.

Document the condition before and after the board-up. The photos of the open, exposed building and the secured one are part of the claim, and they answer the later question of what damage came from the fire versus what came from the weather that followed it.

The fire left water, and it has to dry too

Almost every structure fire is also a water loss. The fire department puts thousands of gallons into the building to knock the fire down, and that water soaks into framing, drywall, insulation, flooring, and the contents. A fire job that ignores the water is a mold job in two weeks.

So the dual damage runs on two clocks at once. The smoke residue is corroding on the dry side, and the suppression water is wetting structure on the other. Both are time-sensitive. The water has to be extracted and the structure dried with the same urgency you would bring to a burst pipe, because wet, organic, fire-damaged material is exactly what mold colonizes, and the building already has compromised air.

Run the drying side by the structural drying playbook. Extract standing water, set the dehumidification and air movement, monitor the moisture content down to a dry standard, and document it. The water-damage mitigation and structural drying guide carries the meters, the targets, and the drying chamber detail. On a fire, you are doing that work and the soot work together, not one after the other.

Removing the soot: dry first, then wet

Soot removal has an order, and the order is the whole game. Dry first. Wet second. Reverse it and you drive the residue deeper and turn a cleanable surface into a stained one.

Start with dry methods. A dry chemical sponge, sometimes called a soot sponge, lifts loose soot off walls and ceilings without water by trapping it in the sponge. HEPA vacuuming pulls the settled particulate off surfaces and out of the air, and the HEPA filtration matters because fire soot is fine enough to pass a standard vacuum and recirculate. Work top down so what you knock loose falls onto surfaces you have not cleaned yet, not ones you have.

Only after the loose soot is off do you wet clean. The dry pass removes the bulk so the wet pass deals with the bonded film instead of a slurry of loose soot. Wet cleaning then uses the chemistry matched to the residue and the surface. The principle is simple and the failure is common: every bit of soot you can lift dry is soot you are not smearing into the finish with a wet rag.

Why dry cleaning has to come before wet cleaning

Dry cleaning and wet cleaning do two different jobs, and they have to happen in that sequence. Dry cleaning, the sponge and the HEPA vacuum, lifts the loose, unbonded soot that is just sitting on the surface. Wet cleaning, the chemistry, dissolves and emulsifies the film that has actually bonded to the surface. Loose soot is most of the volume, and it is the part that smears.

Here is the mechanism behind the rule. Loose soot plus water equals mud. Wipe a sooty wall with a wet sponge and you are not removing the soot, you are spreading a thinned layer of it across a wider area and pressing it into the paint and the porous substrate, where it stains and where the odor sets. Dry-remove the bulk first and the wet step has far less to fight and nothing to smear.

Match the wet method to the residue once you get to it, and hedge the specifics to IICRC S700 and the product manufacturer. Dry smoke may need only a light wet clean after the dry pass. Wet smoke and protein need the degreasing chemistry and dwell time. The order does not change with the residue. Dry always comes first.

Matching the cleaning chemistry to the residue and surface

The cleaner has to match two things at once: the residue you are removing and the surface you are removing it from. Smoke residue is acidic, so the cleaning chemistries are generally alkaline, formulated to neutralize the acid and emulsify the soot so it lifts instead of smearing. Protein and greasy wet smoke call for degreasers built for that film. The product manufacturer sets the dilution, the dwell time, and the surfaces the product is rated for, and those instructions govern.

The surface can override the residue. An aggressive degreaser that is right for soot on a sealed wall can strip, dull, or discolor a delicate finish, natural stone, or an unsealed wood. So you test a chemistry on an inconspicuous spot before you commit it to the whole surface, and you watch for the finish reacting before the soot does. The pH and the dwell time are the two variables most likely to damage a surface when they are wrong.

Do not freelance the chemistry. Hedge the product selection and the method to IICRC S700, the cleaning-product manufacturer's instructions, and the surface manufacturer where a finish is involved. The wrong cleaner either leaves the residue or ruins the surface, and on a fire job you usually only get one pass at a delicate finish before it is a replacement line on the estimate.

Cleaning by surface, gentle to abrasive

After the dry pass, cleaning splits by surface, because the same residue behaves differently on different materials. Painted walls and ceilings take the chemistry and a controlled wet clean, working in sections so nothing dries with cleaner sitting on it. Sealed hard surfaces tolerate more aggressive work. Porous and delicate surfaces, natural stone, unsealed wood, fabric, and high-gloss finishes, get the gentlest method that still works, and some of them are better handled as contents off site.

The judgment is gentle versus abrasive. You use the least aggressive method that actually removes the residue, then step up only where it does not. Reaching for the most aggressive method first is how finishes get destroyed that the soot had not yet ruined. Reaching for the gentlest and stopping there is how the residue gets left behind to keep corroding and keep smelling.

Part of cleaning by surface is deciding what is even salvageable. Some materials clean up. Some are cheaper or impossible to restore and get removed and replaced. That call feeds the structure-versus-replacement scope, and it is better made deliberately than discovered halfway through scrubbing something that was never going to come clean.

Odor removal starts at the source, not the air

Smoke odor removal has one governing principle: remove the source first, then clean, then treat whatever odor is left. Masking is not removal, and a deodorizer sprayed over a building that still holds soot buys a few days before the smell comes back stronger.

The source is the residue and the burned material. Odor loads into porous surfaces and into anything the soot touched, and as long as that material is in place, it keeps releasing odor. So you remove the unsalvageable burned material, you clean the soot off everything that stays, and you decontaminate the HVAC that has been recirculating the smell. Most of the odor leaves with the source. The residual is what you treat after.

Only when the source is gone and the cleaning is done do the deodorization machines earn their place. Run them before that and you are deodorizing a building that is still generating the odor you are trying to remove, which is effort spent against a source you left in place. Source first. Every time.

The residual-odor methods and where each one fits

Once the source is gone and the building is clean, the residual odor that has set into surfaces gets treated, and there are a few methods, each with a place and a caution. Match the method to the situation and hedge the selection to IICRC S700 and the equipment manufacturer.

Thermal fogging heats a deodorizing compound into a fog that penetrates the same paths the smoke took, getting into cracks, cavities, and porous surfaces the smoke reached. It pairs the odor counteractant with the way the odor got there in the first place. Hydroxyl generators produce hydroxyl radicals that break down odor compounds, and they are generally safe to run in occupied spaces, which makes them the default where people or pets remain on site. They work slower, often over several days, which is the tradeoff for being able to run them safely around occupants.

Ozone is the powerful one and the dangerous one. It oxidizes odor compounds aggressively and fast, but ozone is a respiratory hazard, so it runs only in unoccupied, evacuated spaces. Sealing comes last, for surfaces that cannot be fully cleaned, applied after cleaning and never instead of it. None of these is a substitute for source removal, and ozone in particular is not a shortcut around cleaning a building that is still dirty.

Ozone is unoccupied-only, and that is not negotiable

Ozone removes smoke odor well, and it will hurt the people in the building if you run it wrong. Ozone gas is a respiratory hazard. Breathing it causes throat and lung irritation, shortness of breath, and worse with concentration and exposure, and it is harder on anyone with asthma or a respiratory condition.

So the rule is absolute: ozone runs only in an unoccupied space, fully evacuated of people, pets, and plants, and the area stays sealed and signed off during the treatment. After the cycle, the space is aired out and the ozone is allowed to decay back to a safe level before anyone re-enters. There is no occupied ozone treatment. There is no quick pass with people in the next room.

This is the hazard you do not hedge. Hedge the chemistry, hedge the residue classification, hedge the odor method selection. Do not hedge the evacuation. If a building cannot be cleared, ozone is off the table and you reach for hydroxyl, thermal fog, and more cleaning instead. Treat the ozone caution as a hard line in the scope and the safety plan.

Sealing residual odor, after cleaning and not instead

Some surfaces cannot be fully cleaned or deodorized, and for those, sealing locks the residual odor in. A stain-blocking primer or an odor-encapsulant goes on framing, subfloor, or other structural surfaces that still hold odor after they have been cleaned as far as they will clean. The seal traps the remaining odor compounds so they stop releasing into the building.

The order is the whole point. Sealing comes after cleaning, never as a replacement for it. Prime over soot you did not remove and you have sealed the source in along with the odor, which works until it does not, and then the smell finds its way out and the primer has to come off. Clean first, get the surface as clean as it will get, then seal what still carries odor.

Reserve sealing for surfaces that genuinely cannot be cleaned clean, usually rough structural materials, not finished surfaces you simply did not want to scrub. It is the last step on a surface, not the first one.

Contents: pack-out, inventory, and off-site cleaning

The contents are the personal property, and they get their own process. Salvageable items, furniture, clothing, electronics, artwork, and the rest, are inventoried, photographed, and packed out to an off-site cleaning facility where they can be cleaned in a controlled environment and stored while the structure is restored. Cleaning contents on a sooty, wet jobsite re-contaminates them, so the pack-out moves them out of that environment.

The inventory is where the claim lives for the homeowner. Every item is logged with its condition, photographed, and tracked, which separates the salvageable from the total loss and gives the carrier a defensible list. Sentimental and high-value items get flagged for specialized cleaning. Items that are a total loss are documented for the claim before disposal, because an item thrown out without a record is an item the homeowner cannot recover.

Match the cleaning to the item the same way you match it to a surface. Hard goods, soft goods, electronics, and documents each take different methods, and some, especially heavily wet-smoked or protein-coated soft goods, are a replacement decision rather than a cleaning one. The documentation of that decision is what holds up later.

The HVAC spread the smoke, so it has to be cleaned

The HVAC system is one of the main reasons smoke reaches rooms that never saw a flame. While the fire burns, the system pulls smoke into the returns and pushes it out the supplies, coating the inside of the ductwork, the coil, and the blower with soot. Then it sits there.

Skip the HVAC and you have built a re-contamination machine. You can clean every surface in the building, run the deodorizers, and call it done, and the first time the system cycles it blows soot and odor back out of the ducts onto the surfaces you just cleaned. The smell returns, the film returns, and the homeowner cannot understand why a finished job stinks again. The ducts were the source you left in place.

So the duct interior, the coil, and the blower get cleaned or, where contamination is heavy enough, the components get replaced, and the filters get changed out. This is part of source removal, not an add-on. The air filtration guide covers the HEPA scrubbing and the filter side, and a duct system this contaminated is exactly the case the duct-cleaning practice is built for.

Air scrubbing and the particulate during the work

Fire soot is fine particulate, fine enough to stay airborne and to pass a standard filter, so the air in the building is part of the loss and part of the hazard. HEPA air scrubbers run during the cleaning to pull that particulate out of the air, protect the crew, and keep soot you have disturbed from resettling on surfaces you have already cleaned.

Place the scrubbers to capture the air where the work is happening, and keep them running through the dirty phases of the job. Set up the airflow so contaminated air is drawn through the HEPA media rather than pushed around the building, which is the same containment thinking the air filtration guide details for HEPA and MERV selection.

The scrubbers do not replace the cleaning. They manage the air while the cleaning removes the source, and they keep the disturbed soot from undoing the work you have already done.

Restorable structure versus total loss

Part of the scope is deciding what gets cleaned and what gets replaced. Smoke-contaminated finishes that clean up are restored. Charred, structurally compromised, or unsalvageable material is removed and rebuilt. The line between them is partly cleanability and partly safety, and the safety side is where you bring in help.

Charred structural members are the place to stop guessing. Fire changes the strength of wood and steel, and char depth and heat exposure decide whether a member still carries its load. Assessing that is a structural engineer's call, not a cleaning crew's, and the engineer and the AHJ govern what stays and what gets replaced once the damage reaches the structure. Hedge those determinations to them.

On the finish side, the call is economic as much as technical. Some materials cost more to clean than to replace, or cannot be restored to a defensible standard, and those get scoped for replacement. Make that decision deliberately and document it, because the difference between restore and replace is a large part of the estimate and a frequent point of disagreement with the carrier.

The insurance side of a fire loss

A fire job is also an insurance job, and the documentation is what gets it paid. The carrier is reconstructing what happened and what it costs from the record the restoration firm produces, so the inventory, the soot map, the photos, the scope, and the cleaning all serve the claim as much as the building.

Work the claim from the first day. The emergency mitigation, the board-up, the water extraction, and the early soot removal are all documented as they happen, because a carrier pays for damage that is contained and questions damage that was left to spread. The contents inventory separates salvageable from total loss with a defensible list. The restore-versus-replace decisions are recorded with the reasoning behind them.

Keep the scope and the supporting record aligned, and hedge the coverage and process questions to the carrier and the policy, which control what is covered and how it is settled. The restoration firm's job is to produce a clean, complete record of the loss and the work. The adjuster's job is the coverage. Confusing the two is how scope disputes start.

Documenting the loss and the work

The documentation on a fire job is heavy, and it has to be captured as the work happens, not reconstructed at the end. The assessment, the soot map, the residue type by area, the moisture readings on the water side, the contents inventory, the cleaning performed, the odor treatment, and the before-and-after photos all build the record the claim and any later dispute will rest on.

Capture it in the field rather than from memory. A field tool like FieldOS lets the crew photograph each room, log the residue type and the method per area, track the contents inventory through pack-out and return, record the moisture and the drying progress, and tie the clearance and the odor treatment to the same job. The record built on site is the one that holds up, because it carries the timestamps and the photos that prove what the building looked like and when.

The reason to be disciplined about it is the same reason as on any loss: the record is what answers the question later. Six months out, when someone asks whether the structure was dried, whether the HVAC was cleaned, or why an item was a total loss, the documentation is the only thing that answers without an argument.

Field checklist

Common mistakes

• Wet-cleaning soot before dry removal and smearing it deeper into the finish.
• Using the wrong cleaner for the residue or the surface, leaving the film or damaging the finish.
• Masking the odor with a deodorizer instead of removing the burned source material.
• Ignoring the suppression water and letting the wet, fire-damaged structure grow mold.
• Missing the HVAC contamination, so the system blows soot and odor back after the cleaning.
• Running ozone in an occupied space and exposing people to a respiratory hazard.
• Treating a fire like a one-clock cleaning job instead of racing the acidic residue.

Standards and references

ANSI/IICRC S700 is the consensus standard for professional fire and smoke damage restoration, and it frames the assessment, the residue classification, the cleaning sequence, the deodorization, and the documentation. The residue types, the chemistry matched to each, and the odor-method selection are all areas to hedge to S700 and to the cleaning-product manufacturer's instructions, because the specific dilution, dwell time, and rated surfaces come from the product, not from a rule of thumb.

The water side of a fire loss runs on the water-damage and structural-drying practice, where the extraction, the dehumidification, and the dry-standard targets live. The HVAC and air-quality side cross-references the duct-cleaning and air-filtration practice, including the NADCA framework for contaminated duct systems and the HEPA and filtration selection. Confirm the current edition of each standard, because they are revised on a cycle.

Structural fire damage is a structural engineer's determination, not a restoration crew's. Charred or heat-affected framing and steel get assessed by the engineer, and the engineer and the AHJ govern what is salvageable and what is replaced. The insurance scope and coverage are governed by the carrier and the policy. Three things to hold onto across all of it: the acidic residue corrodes, so stabilize fast; dry-clean before wet and match the method to the residue; and remove the odor source rather than mask it, with ozone reserved for unoccupied spaces.

Units, terms, and definitions

Fire restoration carries its own vocabulary, and the same residue or method goes by more than one name across a scope sheet, an estimate, and a standard.

The terms below are the ones that decide a method or a hazard, so they are worth pinning down before they show up in a scope dispute.

Fire and smoke restoration

Stabilizing and cleaning a structure after a fire, removing soot and odor and drying the suppression water

Soot

The acidic particulate residue smoke leaves on surfaces, which corrodes and etches if not removed

Wet smoke

Smeary, sticky residue from a slow, low-heat fire in plastics and synthetics, the hardest to clean

Dry smoke

Powdery residue from a fast, hot fire in natural materials, which lifts with dry methods

Protein residue

Near-invisible greasy film from a kitchen or grease fire with an intense, lingering odor

Dry cleaning

Removing loose soot with chemical sponges and HEPA vacuuming before any liquid is used

Wet cleaning

Removing bonded residue with a chemistry matched to the residue and surface, after dry cleaning

Thermal fogging

A heated deodorizing fog that penetrates the paths the smoke took to reach residual odor

Hydroxyl vs ozone

Hydroxyl generators are generally safe in occupied spaces; ozone is a respiratory hazard, unoccupied only

Pack-out

Inventorying and removing salvageable contents for cleaning and storage off site

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