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Chimney fire damage left charred roof sheathing & framing as an odor source (C) Daniel FriedmanBuilding Fire & Smoke Odor Removal

~ Find & Remove Persistent Sources of Fire or Smoke Odors & Smells
~ Warnings about over-use of ozone generators

  • POST a QUESTION or COMMENT about how to track down & remove or cure fire & smoke odors in buildings, vehicles, or other enclosed spaces

Fire & smoke odor causes, reservoirs, & removal methods:

This article describes seven approaches people use to attempt (with mixed success) to remove fire or smoke odors from buildings, building contents, or from other enclosed spaces.

We also discuss: how does fire cause lingering odors in buildings even where some items are not visibly burned?

How to deal with cigarette or cigar smoke odors. Research on fire & smoke odor control & removal; professional odor fire restoration associations can help find a diagnostic or fire/smoke damage clean-up expert.

Our page top photo shows charred roof sheathing and framing in part of a building structure that was retained following a building fire that we investigated. Owners complained of fire odors coming from this area.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

- Daniel Friedman, Publisher/Editor/Author - See WHO ARE WE?

Smoke & Fire or Burned Food Odors in Buildings

House fire left charred stair rail balusters (C) Daniel FriedmanOdors from building fires, cigarette or cigar smoke, heating system malfunctions, from wood stoves etc. require special expertise for effective remediation, but the basic steps are:

This article describes the procedures used to remove fire & smoke odors from buildings, building contents, vehicles etc.

We also warn about ineffective and even harmful (but popular) methods that try to deodorize smoke or fire smells and don't work or worse, cause further damage, such as over-use of ozone generators.

Photo: charred stair guard balusters in older home in Poughkeepsie, New York, investigated by the author.

Article Contents:

7 Approaches to removing fire, smoke and many other building odors

Kingston house fire damage & odors (C) Daniel Friedman

  1. Removal of damaged or smelly materials & Items

    Remove burned, contaminated, damaged materials that cannot be economically cleaned such as drywall that has been wet, carpeting, and upholstered furniture.

    While some sources recommend removing and washing carpets, in our experience only valuable rugs & carpets that can be professionally cleaned are likely to tolerate soaking without generating a costly mold contamination problem.

    Wall-to-wall carpets that have been wet should be disposed of along with their padding.
  2. Cigarette smoke stains & odor

    Odors and nicotine stains from cigarette smoking have received a stunning amount of attention. Steps listed in this article that are aimed at getting rid of smoke odors depend in part on the environment and the situation.

    For example, special ventilation systems and cigarette smoke odor control equipment are used in areas frequented by smokers. See the citations provided at the end of this section. See Leaderer (1967) and Bubo (2001) et als. cited on this page.

    At STAINS HUMAN OCCUPANT we discuss using sealants to cover and seal stains that are not sufficiently removed by surface cleaning.

    These sealants are particularly helpful in dealing with both stains and odors left over from fires, mold, oil spills, pets, or heavy smokers in buildings.
  3. Cleaning building surfaces

    Clean building surfaces and clean building contents that can be economically cleaned.

    Generally, hard-surfaced building contents and un-upholstered furniture can be cleaned (though experts warn that finishes may have been damaged by heat and may be odor sources).

    Soft goods that can be laundered or dry-cleaned can usually be cleaned of fire, smoke or other odor problems.

    Valuable upholstered furnishings may be salvageable if treated by an expert conservationist.

    Carpeting or area rugs that were not wet or damaged but emit smoke odors might respond to professional cleaning. Carpeting that has been wet or flooded by fire extinguishment, along with its padding, will need to be replaced.

    See CARPET MOLD / ODOR TESTS for carpeting or rugs that have been wet and may be mold-contaminated

    Cleaning of building surfaces & contents may involve HEPA vacuuming, or where an item can be washed without further damage, actual washing with cleaning solutions. For valuable items & artifacts, you should consult a expert conservator or fire damage restoration consultant.
  4. Sealing fire or smoke damaged surfaces

    Seal building surfaces using an odor-sealant coating - specific products are available for fire damaged buildings. See details below in this article.

    Also see MOLD SANITIZER, SPRAY, BIOCIDE USE GUIDE
  5. Ventilating the building

    Use fresh air to remove airborne odors in the building and to help remove odors remaining in building contents or on building surfaces.

    Ventilation will not, however, remove an actual odor source such as heat-damaged coatings, furnishings, building contents that have been chemically changed by exposure to a fire or heat.

    Watch out: while portable or even central air purifiers and air cleaners may improve odor levels indoors, none of these devices can remove an odor from a building where a persistent source is present. The source needs to be identified and removed or treated.
  6. Heating the building

    Removing building or vehicle or other enclosed-space odors using heat - thermal deodorization.

    Watch out: experts do not recommend this approach for fire-cleanup where items involved have already been affected by heat and may be damaged still more by further exposure to heat.
  7. Ozone generators?

    Watch out: Using ozone generators in an attempt to remove odors is generally ineffective for smoke, mold, and some other building odor sources and in fact, excessive use of ozone in buildings or in other enclosed spaces such as in a moldy car or other vehicle can oxidize various materials creating a new odor problem and ultimately increasing the cost of the odor remedy (as those new smelly materials will probably have to be tossed out)

    In our opinion, wet scrubbers (Dickerson 1974) or photocatalyst plasma air cleaning approaches (Lee 2003) hold more promise in this area and may avoid the oxidation issue.

Odor Sealing Paints

Photograph of clear fungicidal sealant on building framing and subflooringLow-odor, low VOC paints & other special coatings can be used to help seal odors from fire-heated or fire damaged structures, and also intumescent sealants.

Watch out: the selection of an appropriate sealant coating to control fire or smoke damage odors must consider the composition of the material on which the coating is to be applied.

For example, we've had very good results using a lacquer or shellac-based primer sealer but you would not paint that sealant on materials that can be dissolved or damaged by the solvents in the paint itself.

Similarly, it may be undesirable to paint some building objects and artifacts with a pigmented sealer - so some of the sealants listed in our article links below may be more appropriate. A clear-coated sealant applied in a crawl space is shown in our photo at left.

And where painting over cigarette smoke stains on walls, ceilings, or other surfaces, you may need to first paint with an oil-based sealer to avoid a bleed-through problem, followed by a lacquer or shellac based top sealant and finally the top coat to provide the colour or texture designed for the finished surface.

Water-based stain killers and sealers may be suitable for some applications, but we've had trouble with bleed-through.

Research on odor sealing paints & coatings

Research & Resources for Fire & Smoke Odor Treatments

Burned vinyl siding & trim on a Poughkeepsie home (C) Daniel Friedman

Photo: burned exterior vinyl siding and trim melting on the front of a fire damaged building in Poughkeepsie, New York.

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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Reader Question: used ozone to remove protein smoke odor, now strange odor remains

House fire damage & odors (C) Daniel Friedman(Feb 21, 2015) Michael said:

My house was cleaned with ozone in order to remove the protein smoke odor. It was cleaned and re-painted as well: ceiling and walls. Now I have strange odor, which is not a smoke.

I suspect the oxidants odors coming from surfaces. It is clear how to remove the odor from the carpet - replace the carpet. However, I do not really understand how to remove it from the walls. Should I re-seal and re-paint the walls? If yes, what paint should I use?

This question was originally posted at OZONE MOLD / ODOR TREATMENT WARNINGS

The house fire image at left illustrates severe fire damage likely to leave further odor problems that will need to be addressed as part of the restoration. This is not the fire discussed by Michael above.

Reply: what is in smoke & why odors remain after an odor-treatment program

Michael,

Really? "Protein smoke odors" ?

Smoke is basically comprised of small but visible particles of unburned material, typically carbon or other substances made airborne during a fire. "Small" here means particles in pm 2.5 range such as wildfire smoke - all particulate matter that is less than ten microns in diameter (10u).

These very small particles can be breathed deeply into the lungs. What's in smoke depends on what was being burned: wood, fabrics, plastics, or food contribute different particles and chemicals to the smoke.

Besides carbon particles, smoke can contain a variety of harmful substances besides particles themselves: gases such as from wood smoke (say burning a wood-framed building or from a wood fire) include acetic acid, benzene, carbon monoxide (CO), formaldehyde, formic acid, heavy metals, nitrogen-oxides (NO2), phenols, sulfur dioxide (SO2), VOCs, and other materials.

Protein odors are the result of burning meat such as a steak, or burning animal fat. You can have a hard time removing these odors from a building.

Smell test method (C) Daniel FriedmanThe odor that remains after a building fire, or after burning a steak, is due to outgassing of odor molecules from incompletely-burned particles that plate out on building surfaces (ceilings, floors, walls, carpets, furniture, draperies, etc) after a fire.

Since you describe an odor complaint that remains after a post-fire treatment it is most likely that the odor is coming from one or more building surfaces.

People's complaints of odors that remain or that are "new" after post-fire odor-treatments typically come from one of two underlying sources:

Surfaces or materials that have received deposits of burned materials have not been adequately cleaned, sealed, or removed and are continuing to release molecules (or even particles) that smell.

The treatment itself, if it was not properly conducted, can produce new odors and smells from a sealant coating or from over-dosing with ozone as is discussed in this article series.

Therefore, before using an odor sealant (such as is used after a fire) and before repainting, you might have better and more economical success by identifying the odor source.

Try the easy smell patch test kit described at

SMELL PATCH TEST to FIND ODOR SOURCE - above the author demonstrates this extremely low-cost and usually very effective smell-patch test that can be used to track down odors to their source in buildings.

When you've identified where the odors are coming-from you have a much better chance at a successful odor-cure.

Question: seal surfaces to stop eye & skin irritation & odors from exposed particle board flooring?

Exposed particle board off-gas odor, skin, eye irritation troubleshooting & sealing (C) Inspectapedia.con A.W. .We are trying desperately to find information about a flooring problem since we've removed carpet and came across your website.

About 3 weeks ago we removed carpet and underlay (green foam pieces) from an upstairs room.

We discovered particle board flooring underneath and there has been a continuous awfully strong odour coming from the room.

The flooring itself is in good condition, not water damaged or pet smell. We've tried everything to clean the space - air purifier, dehumidifier, HEPA vacuum, cleaning baking soda, disinfectant, vinegar and essential oils, and the smell is still there.

It's worse when the area gets really hot but we have to keep the windows open up there for ventilation.

We've had eye and skin irritation, burning stuffiness nose and throat and are now sleeping down the other end of the house!

Is it possible that after 15years (approximately) from being covered with the carpet that the floor, now that it's exposed, would be off-gassing nasties like formaldehyde.

I've never smelt anything like it before or had this reaction.

We want to seal it with something but due to existing sensitivities don't know what to use but we need to do something that works. Our aim is to put new timber flooring over the top when we fix the problem so also need something that will be OK underneath other flooring?

If you can help with any information or suggestions would be much appreciated. - Anonymous by private email 2019/12/11

Reply: formaldehyde? Sealants to try

Exposed particle board off-gas odor, skin, eye irritation troubleshooting & sealing (C) Inspectapedia.con A.W. .While there are exceptions, I think it would be unusual for a 15 year old subflooring to be a noticeable source of formaldehyde offgassing.

Nevertheless, in this discussion I'll suggest both an inspection and testing approach to be sure we're attacking the right problem and an alternative: simply try one of the recommended odor-sealant paints that are used for just this sort of problem.

The reason there is no single "right" answer to the question of off-gassing from an older particleboard product is that off gas rates vary not just by material but by the specific production run and chemistry of individual products made at specific times.

I think that explains why some batches of vinyl window or siding and some cabinets continue to smell for a very long time and some siding products seem to smell indefinitely.

I suggest checking not just the subfloor that you exposed, but other potential off-gas or odor sources using this

SMELL PATCH TEST to FIND ODOR SOURCE first suggested to me by Jeffrey May in Cambridge MA. I as well as our readers and clients have used this method with good success.

As you'll read in our article series on formaldehyde off-gassing, there could be an irritating off-gas product from particle board but also from cabinets and other products.

So look around for odor candidates and consider what else you moved or disturbed.

See details at FORMALDEHYDE GAS HAZARD REDUCTION

and also see FORMALDEHYDE HAZARDS - home

Really? Well you can skip all that fancy stuff if you're sure it's the subfloor you should have success stopping the smell by using one of the paint-sealants commonly used to stop odors in buildings after a fire; many of these are low VOC and after initial drying do not emit odors.

See DISINFECTANTS, SANITIZERS, FUNGICIDAL-SEALANTS SOURCES for some low-odor sealants used for just this purpose.

Reader follow-up

I've added a couple of photos [shown above - ed] you might want to include in the post.

The first one is at the top of stairwell and the green you can see is just left over from some of the underlay foam. Hope this is useful. I'll look into the odour sealants and try to find one that is low VOC.

Question: questionable odor sealant coating after a house fire

Fire sealant not visible on charred attic rafters & roof sheathing (C) InspectApedia.con Ranwin

Can anyone tell me if this is an acceptable result. Remediation company claims the area was treated with a dry ice application and sealed.

I thought sealant had a color to it, and shouldn’t a dry ice application remove all of the charring. - 2019/12/05 ranwin33

Reply:

Ranwin

Sealants used after a fire can be pigmented (usually white) or clear - in both cases the coating is usually visible. Below is an example of a clear encapsulant that we list

at DISINFECTANTS, SANITIZERS, FUNGICIDAL-SEALANTS SOURCES

Photograph of clear fungicidal sealant on building framing and subflooring

I don't know what dry ice method was used nor how thoroughly it was applied. Indeed some media blasting methods can clean wood completely.

If the charring was deep into the roof deck or framing the blasting may not have been able to remove it, leading to a more-important question: should some of this roof structure have been replaced, repaired, sistered?

Ask for or take a photo of the sealant product used - showing (probably in a series of photos) ALL of the product information - and we can comment further.

You can as you may have found, post one photo per comment, but as many comments as you need.

Below is another example showing that some sealants are white. This coating is

from FUNGICIDAL SEALANT USE GUIDE

Mold spray applied after cleanup (C) Daniel Friedman

Question: odors embedded in wood kitchen cabinets

How can I remove smoke odor from burning toast that smells like it’s embedded in a finished wood kitchen cabinet door? - (Feb 8, 2018) Ali

Reply:

Ali

If the wood surfaces are all finish-coated, you can remove odors by using a detergent cleaner.

Beware that there are probably other materials and surfaces that absorb odor in the same area.

Question: cigarette smoke odors from the apartment downstairs

Hi, I wonder if you can advice me about how to stop the very strong smell of cigarette smoke and other domestic (cooking etc.) odors coming up to my apartment from the floor below. I have a converted apartment on the second floor with suspended timber flooring.

I'm going to take off the carpet and lift up the floor boards to see what sort of insulation there might be between their ceiling and our floor.

But could you please tell me what sort of specific insulation I'd need to help stop any odors coming up, as well as anything else if necessary, such as vapour barriers or DPMs etc. ?

Would you please also advice on the order of any materials that you may suggest should be put down, all the way to the top layer of carpeting.
Thanks. - (Oct 24, 2014) Rob

Reply:

Look for and seal the air leaks from below, such as around pipes and electrical wires.

Question: how to avoid smoke from my neighbors

I live on the 2nd floor of a 2-story apartment building.

The neighbors below me are heavy smokers and smoke outside, but with their door wide open, so consequently, their apartment smells smoky. Both of my bathrooms (located in the middle of my apartment away from any exterior windows and doors) always smell very heavily of smoke.

What would explain this? I wonder if somehow the outdoor air is coming in through our bathroom ventilation

I would like to resolve this problem seeing as I have a baby and don't want her inhaling their 2nd hand smoke. - (Dec 3, 2014) Tori

Reply:

Tori

I think to avoid incoming smoke from windows or doors of a neighboring apartment you'd need to close your own windows and doors or open them just strategically, possibly combined with blowing fresh air into the apartment from a window away from the smoke source - the latter suggestion puts your apartment under positive pressure and will resist smoke coming in from other sources.

Question: homes on stilts [pilings] over a mine area, creosote odors

Hi, I have recently purchased a home on the river.

The homes in this area are on stilts and mine has been closed in. The stilts now make a bottom floor. There is a strange tar like smell in the bottom floor of the house where the beams have been encased, or shall I say wrapped by a metal siding cover, slightly exposed

I am worried this is the smell of the treated beams used to keep the house up. What can I do to make the smell go away or to make the lower level livable? How do I know that the scent is creosote? - (Dec 30, 2014) Stephen Dunne Garcia

Reply:

Stephen,

There is more to this situation than just odor. I'm unsure about structural durability, water or moisture issues, and building without a permit.

To test the piling coating you can send a sliver of surface material to an environmental teat lab.

To seal such odors you'd need to enclose the coated items in an airtight wrap - which might give further moisture or rot issues later.


...

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