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Skunk on the Vassar Golf Course (C) Daniel FriedmanBuilding Odor Diagnosis & Cure
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This page provides our index to detailed step by step articles explaining how to to find & get rid of smells & odors in buildings.

These articles explain how to diagnose, test, identify, and cure or remove a wide range of obnoxious or even toxic odors in buildings, in building air, in building materials, or in the building water supply.

In alphabetical order we discuss odors from a variety of sources including animals including pets, dogs, cats, or unwanted animals or dead animals, formaldehyde odors in buildings from building products or furnishings, electrical odors, plumbing drains, plastic or vinyl odors from building products, flue gases, indoor mold odors, oil tanks or oil spills, pesticides, septic odors, sewer gases, and even abandoned chemicals at properties.

Our page top photo shows a healthy-looking skunk rummaging on the Vassar College campus in Poughkeepsie, New York. This is closer than you want to get to a skunk and you'll notice that this one was giving me (DF) the evil skunk-eye.

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?

Building Odor Guide: How to Find the Source of Odors, Smells, or Gases in Buildings

Smell test method (C) Daniel FriedmanThis article gives links to key steps in diagnosing and removing building smells and odors.

To find what you need quickly, if you don't want to scroll through this index you are welcome to use the page top or bottom SEARCH BOX to search InspectApedia for specific articles and information.

Photo: the author demonstrates sniffing - the diagnostic step in a smell-patch test that can be used to track down odors to their source in buildings.

Odor Diagnosis Strategies:

You can start tracking down the cause or source of an odor in one or more of several ways:

  1. ODOR DIAGNOSIS SIX STEPS - taking an orderly approach to odor source tracking

  2. ODOR DIAGNOSIS CHECKLIST - an easy checklist of stuff to examine or test

  3. ODORS GASES SMELLS, DIAGNOSIS & CURE - includes a catalog of places to look when tracking down an odor source - this article

  4. SMELL PATCH TEST to FIND ODOR SOURCE - procedure for testing specific surfaces or items to see if an odor source of if they have absorbed and are re-emitting an odor

Checklist of Places to Look & Things to Do to Track Down an Odor to it Source

Here are some possible sources of an odor or smell in building air, water, mechanical systems, heating, cooling, or other locations.

Odor Traced to HVAC Condensate Pump

Condensate pump (C) Daniel FriedmanAn InspectApedia reader notes:

[We] had a very bad smell in basement some days worse than others changed seal on toilet at the top basement steps re caulked the lead seals on the two cast iron stacks.

The days we washed clothes [the smell] seemed worse so we washed one day and didn't dry until the next day. When we ran the dryer the smell really was bad.

So I got on the floor started smelling every thing I could find. I finally got by furnace and got close condensate pump [on the floor next to] the air handler [heating and air conditioning equipment]. And there it was [the source of the horrible odor].

I had installed [the condensate pump] about five years ago and I had never cleaned it. What a mistake. I [removed and thoroughly cleaned the condensate pump] AND NO MORE SMELLS! - Gene Lovasz

Odors coming from dirty condensate pump reservoir

Thanks Gene for pointing out that a dirty condensate pump can be a source of unexpected odors and smells.

I suppose that on an HVAC system whose condensate pump runs only seasonally, water left in the pump body may support both algae and bacterial growth that could smell horrible. Cleaning the pump with household cleaner or even a dilute bleach solution was a smart step.

I'd take a look at the condensate pump tubing as well; sometimes crud can collect in a low spot in the plastic drain tubing that ultimately blocks drainage.

Plumbing Vent leaks (C) Daniel Friedman Cheryl Lidawer Bathroom odors & smells,

other than normal ones produced by humans, most often involve sewer or septic gas complaints that are traced to plumbing system problems.

Examples of plumbing problems that you should investigate in tracking down a bathroom odor are Condensate pump (C) Daniel Friedman

Gas leaks at plumbing vent (C) Daniel Friedman

 

Steps to Get Rid of Baby Powder / Perfume Odor in a Building

Getting rid of baby powder odor - the HighHiker perfume odor sealant chronicles - This wegsite is really impressive.

Re: getting rid of baby powder odor.

Will be implementing your smell patch test (very clever idea).

(See SMELL PATCH TEST to FIND ODOR SOURCE )

Meanwhile, someone mentioned a dry steam vapor intervention.

Never heard of that before and wondered if you have any thoughts about it. Look forward to hearing your thoughts, as well as thoughts on sealing other than shellac (which we've tried).

This site is really impressive. The amount of information you have amassed and organized is unbelievable and your willingness to so generously (and quickly) answer questions from the public is simply awesome! Your passion to share info, to help people, to exchange info and learn is very exciting and much appreciated! - On 2019-07-10 by Anonymous -

Moderator reply: dry steam intervention for smells? Dubious IMO.

Let us know if the smell patch procedure pins down the offending surface; that'll tell us how to proceed and also keep us from ripping out the wrong stuff.

If you shellac'ed a suspect odor emitting surface and it made no change I suspect we've not found the offending source.

look also for odor transport via heating or cooling air ducts.

"Dry steam" whatever that is - might help clean some surfaces or materials; it won't penetrate deeply (in my experience) such as into thick carpet, carpet padding, upholstered furniture, contaminated drywall, etc.
IMO it makes sense to find the odor source first then decide the treatment.

Thanks for the nice comments; working together helps us all.

Reader HighHiker follow-up:

BABY POWDER-ISH SMELL FOLLOW UP REPORT & QUESTIONS:

Did the smell patch tests, setting up in numerous locations which confirmed that the master bathroom is where the most intense smell is and it’s where we know the former owners had a plug in going for Lord knows how many years.

We had some upper cabinetry removed from that room last week because the interior of it reeked include some spots where it seems a scented product might have spilled and the exterior was also heavily scented. The lower cabinets beneath the sinks are also scented, though not quite as intensely. The closet in the room also holds the smell quite strongly.

At this point I’m assuming the dry wall (which has two coats of fresh low VOC paint on it) has absorbed the odor, esp because these perfumed products use oils that leave a residue.

Tests on walls in the rest of the house showed that a few small areas where we had dry wall replaced during some remodeling gave off no scent at all. Most other areas of original dry wall (again, 2 coats of fresh paint) had a faint scent.

We’ve had the HVAC ducts cleaned. The original carpet was ripped out 13 months ago right after we bought the house. We live in a climate where you can’t open windows most days due to extreme weather (very hot and humid or very cold), Running air purifiers w/carbon filters has not helped. And worst of all is that in the 13 months since we bought the house, there’s been no perceptible improvement in the smell.

I fear the only solution would be to rip out dry wall and replace it but am hoping and praying you have another idea or ideas. Looking forward to your reply.

PS ~ BABY POWDER POST: The faint smell from walls farther from the master bathroom was not exactly the same as the smell in the bathroom. It was like it had slightly morphed into perfume/paint odor.

Again, faint, but something detectable (to someone w/a very sensitive sense of smell; many don’t smell it at all). BUT, where we put up new dry wall and used the same paint, there was absolutely zero odor. I wonder if the paint somehow interacted w/the perfume smell to create the faint smell on the areas with original drywall. Realized this might be a useful nuance to share.

Moderator reply: Paint interaction to produce odor ?

Paint interaction to produce odor is an interesting thought;

Most likely the effective solution is to coat an odor-emitting wall and ceiling with a sealant paint such as those used after a building fire, followed by a top coat of primer and finish color of your choice.
I'd try that before ripping out drywall.

Reader follow-up: water-based paint w/sealant in it isn't highly effective against organic scents/fragrance

Thanks so much for the very fast response. It is greatly appreciated. Since my wife is very sensitive to VOC's, do you know if these sealant paints tend to be very toxic and stinky and if so, if once painted over w/regular paint (we would plan to use the same low-VOC pain we already used that was terrific) the regular paint will mask the odor.

I'm guessing not since the whole idea here is a paint that seals in odor, so if the low VOC paint isn't a sealant type of paint, then we could be stuck w/the sealant paint odor, no?

Also, do you have any perspective on why, after we coated the interior walls and shelves of the most smelly cabinet (before we eventually had to remove it) with a few coats of pure shellac that didn't seal the odor in? Because the lower cabinetry is quite perfumed and we're trying to figure out how to deal with that as well as the walls. Thank you, in advance, for your continued guidance.

Update: Spoke w/someone at a building supply co that sells products w/less toxicity and/or VOC's than commercial brands.

Was told that water-based paint w/sealant in it isn't highly effective against organic scents/fragrance because their molecules tend to migrate and water can even enliven them and heighten the smell. What's your take on this?... Hope all went well at the DDS. 

Moderator reply:

That has been my experience as well. For that reason I generally use a lacquer based primer sealer or similar product.

Reader follow-up:

Hmm, that sounds pretty smelly in its own right. Meanwhile, reading and consulting about shellac, have learned that: (1) to use as a sealer you need the kind that's had the wax removed (and we don't remember if we bought that kind or not) and that the premixed kind has a relatively short shelf life and you have to do a bit of legwork to find out how old the can is.

So we're wondering if the multiple layers of shellac that we applied to the wood cabinetry was ineffective because we used the kind w/naturally occurring wax and/or the can was old and the product had degraded. alas..

So we've got two challenges: the wood cabinetry and dry wall. This should eventually off gas, but the fact that there's been no discernable improvement in a year does not bode well. Any other thoughts?

Moderator reply:

Yes lacquer off-gasses but the solvent is very volatile and tends not to leave a residual. And it's later top coated with the finish paint. You can use low VOC for the final coats. Lacquers and other fungicidal sealants and post-fire remediation or repair work sealants are usually effective - PROVIDED we've properly identified the odor source.

Reader follow-up: what kind of lacquer sealant paint?

My search for lacquer paint keeps turning up lacquer for finishing woodwork. Also, I wonder if using a water-based paint over it (assuming I can find lacquer base coat paint), I wonder if the paint will adhere well or if it would tend to peel off.

Any recommendations on these points? Thank you for your continued help. We've tried everything and are really at the end of the line at this point. Your guidance is greatly appreciated!

Moderator reply:

B-I-N Primer Sealer Odor sealant paint from Zinseer cited & discussed at InspectApedia.comExamples of two brands of lacquer (or actually shellac) sealer prime coats

Bin Primer Sealer (Zinsser)
or
Enamelac

I've used these successfully since the 1970s

These are fast-drying primer/sealer paints.

Bin lacquer primer, sold under the Zinsser brand is a Rust-O-Leum paint product.

Here are two technical data sheets provided by the company

B-I-N® SHELLAC-BASE PRIMER ULITMATE STAIN BLOCKER from Zinsser [PDF] Technical Data Sheet, Rust-Oleum Corporation Form: GDH-71 11 Hawthorn Parkway Vernon Hills, Illinois 60061 USA Phone: 877 385 8155 Web: www.rustoleum.com

Excerpt: Blocks stains and odors resulting from water & fire damage, seals stains from dark colors, grease, rust, creosote, asphalt, crayon, lipstick, graffiti, markers, knots, sap streaks, tannin bleed, etc. ... Permanently blocks most every kind of odor.

Or for U.K. readers

B-I-N® SHELLAC-BASE PRIMER-SEALER STAIN KILER BOND COAT [PDF] Zinsser® manufactured and marketed in the UK by: Tor Coatings Ltd., Portobello Industrial Estate, Shadon Way, Birtley, County Durham, DH3 2RE. T: +44(0)191 410 6611 F: +44(0)191 492 0125 E: enquiries@tor-coatings.com www.zinsseruk.com

Excerpt: It also seals in urine and other animal odors from smelling.

Reader follow-up:

Thank you, Dan. Will check these products out and keep you posted! Thank you for your incredible generosity and passion to help others and educate. It's most impressive.

Re: lacquer on drywall: Would the surface need to be sanded after it dried before applying the paint/color we want? It seems like lacquer would form a coat that might make it hard for the paint to adhere well.

Moderator reply:

Glad to assist - the discussion helps all of us.

No it doesn't need to be sanded. In fact the company considers it a "bond coat"

Reader follow-up:

Thank you! Here’s an interesting update on the perfume smell in the bathroom cabinetry that hasn’t diminished despite throwing everything but the kitchen sink at it! Many months ago a contractor suggested applying a coat of shellac to seal the perfume odor in. We did that. No improvement. Four coats of pure shellac later, no improvement.

Most recently after consulting w/an amazing person at a green building supply co, we were told that pure shellac will work if

(1) it’s 100% wax free, and

(2) it’s not old (apparently the shelf life is only a year or two).

(They also recommended applying a coat of laquer over it.)

We couldn’t remember if the shellac we’d used before was wax free and/or what the age of it was. So a couple of days age we bought a can of pure shellac that said 100% wax free and contacted the manufacturer to find out how new it was.

(They told us how to figure out the manufacturing date from the LOT number.) The can was fresh off the assembly line, so we applied one coat of this hopefully new and improved shellac and, voila! The perfume smell on the shelf we tested was gone!

We’re going to put a coat of the Acrylaq on it as was recommended just to be sure, but, wow. It’s amazing to think that the type of shellac (wax free) and age of it could mean the difference between being ineffective or completely effective to seal in perfume smell. Onward to finding someone to treat the large amount of bathroom cabinetry that we hope will soon be rendered odor free and then onward to tackling the dry wall!

Moderator Reply:

That is interesting and uf you find it makes a difference, will be helpful to other readers.

When you apply the shellac do confirm that you as re coating only surfaces previously shellaced, else the result won3t ve clear.

Keep us posted.

Reader follow-up:

Yes, right now we're only re-coating surfaces that had been treated (unsuccessfully) with shellac which still smelled as horrible post-shellac as prior. But now the perfume smell is completely neutralized after using the 100% wax free and a can we know is fresh.

We'll soon do a test of a perfumed surface that was never treated w/shellac and if it works, we'll need a professional to handle that job because of the scale of it and because it involves exterior finished wood.

We also plan to contact the person at the green building supply place who's been enormously helpful to ask if using a lacquer finish over the shellac is necessary since the shellac seems to have done the trick. Will be interested to learn if, over time, w/o the lacquer, the smell will start to leach through the shellac. Will keep you posted..

Moderator Reply:

please tell me the specific product that you used previously brand or product that you're trying now. I want to look at the chemical detail

Reader follow-up: Zinsser/Bulls Eye pure shellac

The brand we used both times was Zinsser/Bulls Eye pure shellac. The first time we used it, we don't remember if it was wax-free or not, because that variable wasn't on our radar.

We also don't know if the can we bought was old. This time we used the same brand of pure shellac, but made sure we bought the 100% wax free and also confirmed that the product was not old. (The company explained out to figure out the date from the lot number on the can.)

2019/08/08

Update w/some disappointing news: After applying a coat of wax free Shellac to the entire sink cabinet area (all surfaces), the experiment we did w/one shelf didn't hold up and we found that even the smell of that shelf (which had been neutralized shortly after applying the shellac) has a bit of perfume smell leaching out. In addition, after coating the cavity of the cabinetry w/shellac, the odor is quite gross ~ the perfume smell is there, but it morphed into something quite noxious.

So we thought that perhaps the added layer of lacquer really is necessary. However, after applying a coat of lacquer to the shelf, the perfume smell is still there. More faint, but still easily detectable. Then, after speaking w/a different customer service rep at the green building supply company we consulted w/about all of this recently, we were told that the shellac + lacquer plan has been tested to seal in formaldehyde, not necessarily perfume smell

They recommended applying 3 coats of lacquer, allowing at least 24 hrs of dry time in between. But still, even doing that, we're in the trial and error territory not evidence-based recommendations, and losing our optimism. However, since you suggested lacquer for the dry wall (haven't gotten to that project yet) we're holding out a shred of hope that perhaps lacquer will prove to be effective. If we use enough of it. And cross our fingers. And have good luck. And pray!

Moderator Reply:

That's both surprising and disappointing.

FUNGICIDAL SEALANT USE GUIDE includes both pigmented and opaque sealants widely used after building fires and after mold remediation jobs; in the sites I've inspected a remaining odor was not a problem except when the remediation work itself had missed a problem area.

Also see DISINFECTANTS, SANITIZERS, FUNGICIDAL-SEALANTS SOURCES

 


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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

On 2022-09-10 by Annonymous - Steps in Resolving this complaint: mudding and skimming pre-mixed drwall coating product smells - can't get rid of it

Removed built-in desks from a very small room. Had new dry wall hung. Covid hit, so work came to a halt.

Now, picking up where we left off. Mudding, skimming, and sanding the dry wall finished up a few days ago. Pre-mixed product used when taping was pretty benign. Slight smell when wet and 24 hrs later, not much of an odor. However, for the subsequent mudding and skimming another pre-mixed product was used (same manufacturer) and it smelled pretty strong.

Despite running an exhaust fan non-stop, by the next morning it still stunk. Didn’t smell like what I’m reading about online with “bad” compound that is described as smelling like sulfur. This doesn’t smell like that, but it’s very difficult to describe the odor other than it being very noxious.

When I go in the room, my eyes burn and I’ve found that if I check the smell too often during the day, I get throat irritation, as well.

We talked to the drywall professional the day after the first application and he said the compound wasn’t bad. He said he can tell when it’s bad and this wasn’t. So, with that said and hoping it would off gas, we finished the job using that product. It has now been a little over a week since the first application and the smell is as strong as it ever was.

We are running the exhaust fan all day long. The room is small. Everything I’m reading about this product says it should be completely inert within 24 after it cures.

My walls and ceiling stink. I can’t open the door to the room. I can’t put my things back in the room. I can’t use the room. I’m trying to minimize having the odor spread throughout the house.

I fear something was wrong with that compound despite whatever they said and I don’t know how to fix this short of ripping out all the walls and ceiling and starting over, which is overwhelming to consider.

I’ve looked into primers that are made to seal in odors, but they sound like they have very high VOC’s, smell very strong, and that the smell can linger for quite a long time. (They also sound rather toxic.) I don’t want to exchange one smell for another.

I’m concerned that the more time that passes, the more the smell will leach into the wall cavity behind the newly mudded walls (which we put a coat of primer on to eliminate dust issues) and start to infuse the 2/4’s and eventually the drywall on the other side (the other rooms).

I need a solution, and preferably one that isn’t draconian. Do you have guidance to provide?

On 2022-09-10 by InspectApedia-911 (mod) - compound may have been contaminated with mold

@Annonymous,

Before taking draconian measures let's diagnose the problem:

Joint compound is not normally smelly.

If the smell is moldy then the compound may have been contaminated with mold - which absolutely can happen particularly if a bucket of mud was opened, used, then stored for months. I NEVER use such compound - it's far cheaper to toss a bucket of contaminated drywall mud than to have to later tear down walls.

If the smell is something else such as a chemical odor - I'm baffled as that's not a normal drywall issue.

If you confirm that the odor is from the walls or ceilings your options are to try a sealant paint (Search InspectApedia.com for FUNGICIDAL SEALANTS & PAINTS) for examples - those are also used to seal odors after a building fire.

OR

To remove and replace the smelly drywall.

See also CHINESE DRYWALL HAZARDS 

On 2022-09-10 by Annonymous

@InspectApedia-911, The smell is not moldy. It's a chemical smell and it was there from the moment the compound was put on. The All Purpose was fine, but the other product that was used was really noxious. As for sealing paints, I have the impression they are quite noxious in their own way and am concerned about exchanging one strong smell for another.

I am chemically sensitive and my spouse and I also go to great lengths to attend to our indoor air quality, so this is huge for me when moving forward with building products. Is there a product you could point me to that doesn't have this feature to it?

My research thus far suggests they're all incredibly smelly and that the smell can last for weeks on end. We are doing an experiment today with one product, applying a bit to a piece of foam core to see how long it takes to off gas. I will check that section on this amazing site that you suggest.

And, finally, I see you are a moderator here. I hope that is because the person who started this site is so overwhelmed with questions that he needs help and not because he's unwell. Sending prayers either way.... And thanks.

I went to the section you recommended and couldn't find products of the type you mentioned. So I clicked into other sections and they didn't have these products either, at least not that I could find. Can you better direct me? This website has a wealth of information - a treasure trove - but sometimes it's complicated to navigate because there are links within links within links. Thank you.

Also, as long as I'm getting back to you (again) I want to clarify something. If it turns out the compound did have some mold growth, are you saying that using some kind of sealant over it is a reasonable option?

What about the other side of the drywall (the back that faces the wall cavity)? Wouldn't that eventually become vulnerable to whatever spores were in that compound?

On 2022-09-10 by InspectApedia-911 (mod)

@Annonymous,

We list sealants at

FUNGICIDAL SPRAY & SEALANT USE GUIDE

MOLD SANITIZER, SPRAY, BIOCIDE USE GUIDE

And we discuss non-mold "chemical smells" at

CHEMICAL ODOR SOURCES

If the smell was there from day-one, I sure am sorry that the workers continued to use the product.

IF you don't want to use an odor sealing paint (usually those off-gas pretty quickly given adequate ventilation) THEN

in my OPINION you should

1. confirm for sure the odor source is those surfaces and not something else in the building

See SMELL PATCH TEST to FIND ODOR SOURCE

And if that's confirmed, you have no choice but to remove the materials.

On 2022-09-12 by Annonymous - IAQ consultant will take a detailed history, assess, and run some preliminary tests

@InspectApedia-911, Thank you for your continued guidance. I did set up smell patch tests on various surfaces in the room. (Learned that from this website along with so many other things!) My husband and I have done that in the past trying to track down the source of perfume odors and it worked very well, smelling each sample "blind" so as not to be influenced by knowing where it had been taped.

I haven't removed and smelled any of the ones for this challenge because I'm allergic to mold and since we don't yet know if we're dealing with mold, I'm reluctant to stick my nose into samples that may have spores on them.

I'm becoming increasing concerned that mold is the culprit since compound should have no odor, and certainly not after 24 hrs, and after reading one of the pages you linked to that said some people smell mold as a "chemical" smell. I wonder if the product that was used was developing some mold growth that was not yet visibly evident.

Still, given the fact that these products should have no odor and be quite inert within 24 hours, it mystifies me as to how dry wall professionals wouldn't realize there was a problem as soon as they began to apply the compound, no less to discover the strong odor 24 hrs after the first application, and to then keep going, insisting we keep using this product or else the job would come to a halt.

Our exceptional IAQ consultant will be here early this week to take a detailed history, assess, and run some preliminary tests.

One question I have for you at this juncture is, if the compound had mold growth in it, should I presume that painting a sealant would not make sense? If there was mold (and subsequent bacteria) in the compound, then it's in/on my wall. The idea of sealing that in seems questionable because when I think of mold remediation, I think of:

  • containment
  • finding the moisture source and fixing it
  • removing as much damaged material as possible
  • cleaning what can't be removed
  • doing repairs to get the area back to normal
If I put a sealant on the walls (and ceiling... ugh) what's to keep the mold from growing into the back of the drywall that has no sealant and impacting that material, along with, potentially, studs and the air in the wall cavity that can move throughout the building? I would welcome more discussion about this so I can better understand.

Also, we applied one coat of the Zinsser sealant on a piece of foam core just to see how strongly it smelled and I was surprised to find that it wasn't as irritating as I anticipated it might be. That said, it would be on my walls and ceiling and not a 12" x 18" piece of foam core, so, hmm. .

On 2022-09-12 by InspectApedia-911 (mod) - if mold contaminated, surface sealing would be a mistake

@Annonymous,

You are absolutely right and I should have been more clear.

IF we think that the drywall or joint compound used to tape and install the drywall was mold contaminated, surface sealing would be a mistake.

The only trusted and proper response in my experience and opinion is to remove the drywall completely, inspect and if appropriate, clean the exposed surfaces, and install new drywall.

IF you find that there have been actual water leaks into walls or ceilings, and that that's the smells source, then that's another story and we're back to the basic mold odor cure steps that I harp-on and that you've summarized so nicely.

BTW I would not rely solely on opinion or advice from the installer who is in a position of conflicting interests.

I might make some test cuts in most-suspect locations but you're right, absence of evidence is not evidence of absence.

On 2022-09-14 by Annonymous - does formaldehyde have to be listed if it's present at low levels in building materials?

@InspectApedia-911, Thank you for your ongoing guidance. Quick question:

The ingredients listed for the products used don't include formaldehyde.

Do you know if it only has to be listed if it's above a certain concentration of if it must be listed no matter how small the levels?

So far, I haven't been able to find the answer to this question at the EPA or OSHA web sites. Thank you!

On 2022-09-14 by InspectApedia-911 (mod) - possible formaldehyde off-gassing from drywall

@Annonymous,

Speculation about formaldehyde from just the information in this discussion has so little information-basis as to be almost certainly wrong.

But we do have something more to say about possible formaldehyde off-gassing from drywall (doing more research on this question):

In my much-older experience (hanging drywall in the U.S. in the 1970s-1980s), formaldehyde or chemicals containing formaldehyde could appear in drywall mud to which it was added as a plasticizer or as a drying agent (“fast drying joint compound”).

In 2010 James Vallette, in “Formaldehyde Additives in US-made drywall” published by HBN - the “Healthy Building Network” https://healthybuilding.net/blog/286-formaldehyde-additives-in-us-made-drywall

asserted that there was considerable evidence that some drywall or drywall mud contained notable levels of formaldehyde.

Really? Well perhaps yes, but as of this writing (2022/09/14), NONE of the studies or sources cited by Mr. Vallette could be located online, and some of the websites like formaldehyde.org have disappeared entirely. We were unable to locate other important sources such as his cited US CPSC and US EPA and California studies and we continue to search for these. [Citations and copies are needed - Ed.]

Watch out: according to the the "Formaldehyde Council" (an industry trade association whose 2010 website formaldehyde.org and article Drywall: Not Made with Formaldehyde-Based Resins http://formaldehyde.org/blog/entry/Drywall_Not_Made_With_Formaldehyde-Based_Resins has disappeared [this is why here at InspectApedia.com we copy and date such articles, authors, resources - Ed]), formaldehyde isn't a normal ingredient in drywall nor joint compound.

BUT some industry sources have said, quite fairly in our OPINION, drywall can act as an odor or chemical smell or gas “sink” - that is it can absorb odors and then can continue for a long time as a persistent odor source. We have found that very common in mold-contaminated buildings.

BUT even in the industry some sources say otherwise:

Some grades of commercial drywall contain naphthalene sulonate formaldehyde and sodium lignosulfonate (Lyondell Chemical Co. 2003) and (Geo Specialty Chemicals who sell that chemical to USG, Georgia Pacific, National Gypsum and James Harde).

BUT according to independent reliable sources (US EPA and CA DOH) formaldehyde was indeed used in at least some drywall products and in some cases drywall was found to emit formaldehyde indoors at

When these information sources disappear we don’t know why: were they later discredited or were they removed by interested parties.

So we include a PDF copy of Vallette, James FORMALDEHYDE ADDITIVES in US-MADE DRYWALL [PDF] (2010) - retrieved 2022/09/14, original source: the “Healthy Building Network” https://healthybuilding.net/blog/286-formaldehyde-additives-in-us-made-drywall

Copy at

https://inspectapedia.com/indoor_air_quality/Formaldehyde-additives-n-US-drywallhealthybuilding.net.pdf

If your expert is confident in fact formaldehyde has been correctly identified at abnormal levels some further investigation is in order.

See help offered at

FORMALDEHYDE GAS SOURCES in BUILDINGS you’ll see that other products including some particleboards and laminate flooring are common formaldehyde offgas sources in buildings.

But

Don't rule out that someone added something to the drywall mud such as a chemical or drying agent. There were add-on drying agents, thus that could have been used even if the product, from the manufacturer, didn’t contain formaldehyde.

Also be sure to read

CHINESE DRYWALL HAZARDS

On 2022-09-15 by Annonymous - This site provides an amazing public service.

@InspectApedia-911, Thank you for taking the time to share all of that. I'm aware of the Chinese drywall debacle. That doesn't apply in my case.

I understand that drywall can absorb odors and become a conduit for off-gassing things it's absorbed, but we've had and had no issues in our home w/such odors and are extremely diligent about our indoor air quality (ie, avoid synthetic carpet, MDF board, upholstered furniture, etc).

We monitor our indoor air quality, humidity, check for any sign of water intrusion, etc, and are confident we can rule out mold. We are also confident the dry wall contractor did not add anything to the mix other than water.

We will continue to investigate in a step-wise fashion. Thank you for all of your help. This site provides an amazing public service.

 

On 2022-08-27 by NSB - Diagnose the source of a sour smell in our garage?

Our house has an attached garage, and there is what I would describe as a sour smell that (I think) is originating from there. I also smell it in the foyer, front hallway, stairway leading upstairs, and in the hallway upstairs, directly above the garage. My husband claims he doesn't smell anything, but friends of mine do, and so does my son.

We've moved the garbage cans out of the garage, but the odor persists - never gets worse or better, just pretty much h stays the same. My friend had (dead?) mice in her walls, and said that's not what this smells like. It's more just a bad, sour smell. I'd say it's more garbag-y than dead animal, but I don't really know.

Any ideas on who to call &/or how to figure out the source, and finally, how to get rid of it?Thanks in advance for all advice/suggestions

On 2022-08-27 by InspectApedia (Editor) - several approaches to tracking down an odor to its source

@NSB,

Sensitivity to odors varies enormously among people so it's no surprise and not necessarily helpful if some, including hubby, say they don't smell anything. Having an odor presence corroborated by other people helps rule out the chance of an individual's medical or neurological problem and lets us get back to focusing on the building.

The Recommended Articles links above give you several approaches to tracking down an odor to its source: an odor log, smell patch testing, visual inspection.

From just your note we don't know if what's needed is surface cleaning, drywall test cuts or replacement, or something else.


On 2021-06-10 by WC - strong Glade Air freshener type smell in our cabin - where's it coming from, what do we do?

I have a cabin on a lake, surrounded by trees that has an unexplained, VERY strong Glade Air freshener type smell. It is hard to describe and unfortunately it is not pleasant and when you leave, the smell stays in your hair and clothes. It is so strong that you can can smell it outside when the door is open.

I have had multiple people (Plummer, HVAC, Mold Inspector, Odor remover company) out trying to diagnose what it is and where it is coming from to no avail. I have never smelled anything like it before. It is throughout the entire cabin with the exception of the bedroom.

I have repainted, installed roof vents, new insulation, fresh air intake, exhaust fan in the bathroom and replaced the furniture. The cabin has a tendency to have high humanity that can exceed 70%, so it is important to run a dehumidifier. Do you have any idea what could be causing that type of smell?

On 2021-06-15 by DR

@WC, does your cabin have a septic tank? Sometimes they use some strong fragrance to mask the smell and it can be detected outdoors as well.

On 2021-06-15 by Anonymous

@DR, thanks for helping out with that opinion.

I'd like to know where your idea originates; that is, I am not aware of products being offered to deodorize septic tanks, nor of any need for them.

With the exception of modest low odor levels near some aerobic equipment, or a downdraft from a roof vent at some sites, in general, a properly operating septic system ought not be smelling up the area with anything.

On 2021-06-15 by inspectapedia.com.moderator (mod) - diagnose this air-freshener odor

@WC,

Diagnostic & Contextual Q&A to Help Track Down a Mystery Odor to its Source (off the cuff, supplementing our more organized approach given above)

I'll be glad to join DR in trying to diagnose this air-freshener odor at your property. I need, however, more details to be useful.

Let's not do anything else that's costly without some more careful inspection and diagnosis. Don't hire someone who does an "air test" (not diagnostic) nor a "quick walkthrough".

What are the country and general location (city, county, climate) of the cabin?

What are the cabin and plumbing and septic system age?

How long have you owned the property?

When did you first notice the smell? Any events preceding that that you can name?

What is the septic system type: conventional tank and drainfield, cesspool, aerobic, mound, etc?

What's the septic maintenance history: is the tank pumped on occasion?

Most important: inside the cabin - as I take it this odor is an in-cabin odor complaint - where is the odor strongest? Have your smell-test person spend time outdoors in fresh air, or arrive anew at the property after an absence of hours or days, then walk quickly through the cabin to form an opinion of odor strength.

What cleaners, chemicals, paints, sealants, insect or pest treatments have been used in the cabin? Any history of spills or stains suggesting spills of anything?

Is there a crawl space? Did your experts examine conditions there?

Is there an attic space? Ditto?

We could probably reduce the odor complaint by installing a heat-exchanging fresh air ventilation system but frankly I much dislike pretending to "solve" a problem by treating the symptom before we find the source.

With a bit more opinion of odor strength we might try some simple low-cost tests like using the ODOR LOG we describe in the article above and also our SMELL PATCH TEST KIT if there is an area or surface we suspect.


On 2021-03-31 by Veteran - Smell in my house in the Siskyou Mountains in California

I am a veteran who lives way off grid in the siskiyou mountains in California. My house is 2 levels the bottom is below grade but only on two sides. There has been a smell in the house since I bought it. It’s not what I would call a mildew or moldy smell.. kinda like stale patchouli. It gets in our clothes and everything. The house is dry no leaks ..

however there’re a few plumbing trenches in the slab that are dirt floors with a wood deck at slab height.

It does smell musty down there.

For the past two years I seem to have developed allergic type symptoms. Feel like I drank a 12 pack hangover everyday.

So I’ve been opening up some parts of the house. In top floor the ceiling is 1x6 pine but not t&g so there’s 1/4” gap between panels...found dry looking black mold on denim insulation and on backs of panels. I can’t get anyone out to the house to inspect or remediate. Can you help?

On 2021-03-31 - by (mod) -

Vet

Starting at the top of this page we have organized a series of steps and suggestions for tracking down an odor . Please take a look as that's far more-complete than if I try to make up that advice all over again off-the-cuff here. DOn't hesitate to ask follow-up questions or to tell me what you are finding.

I would add that finding some mold hidden in a ceiling suggests that there may have been leaks and a larger, more-serious mold contamination issue that's worth further investigation.

Also check with your doctor, and ask her if your health complaints might be caused-by or aggravated-by the smell complaints and mold reservoirs you've observed.


On 2021-02-07 by Sarah - Metallic odor throughout my house - where do we look for its source?

This afternoon there was an unfamiliar odor throughout the house that had a slight metallic quality to it. Didn't smell it coming from any of the HVAC vents and didn't smell anything outside. Despite that, I got suspicious about the inline humidification system, so my husband went to the unfinished basement to see if it smelled (which it didn't) and replaced the inline humidification piece where the water drips down and also wiped the fan.

He didn't see or smell anything unusual. We opened windows to air the house out (Bbbrrrrrrrrrrrr) and then, with the indoor air more returned to baseline neutral smell, as an experiment, I shut the inline humidifier off and just let the heat run, as needed.

The smell did not return. So a few hours later, I turned the inline humidification system back on and after a couple of hours I could smell a subtle note of that somewhat metallic (for lack of a better way of describing it) smell. So I shut it off.

We get our HVAC serviced twice a year and keep our indoor humidity well below 50% year round (though it's a bit of a challenge during warm and humid summer months).

We have an excellent IAQ person we work with and are vigilant about moisture, mold, etc. Got any ideas or direction to point us in?

On 2021-02-07 - by (mod) -

While there could be a different odor source, Sarah, your own Sherlock-Steps point to the humidifier;

You might want to clean and disinfect the humidifier, including any water reservoir and filter it uses.

More examples and details are at CENTRAL HUMIDIFIERS in BUILDINGS

Do let me know if that works out for you.

On 2021-02-08 by Sarah

Thank you. I read the info in the link you provided. I think we solved the source of the odor (think it came from something external and the humidifier was a red herring). That said, I dislike the idea of inline humidifiers for all the reasons you note. However, when you live somewhere that gets really cold and dry, free standing units don't seem practice and they,

also, carry similar risks re: mold, mineral deposit build up, and, I think, white dust (though maybe that's also a risk w/inline systems). I also dislike having them run in bedrooms because of all the textiles (not to mention the bed).

These free-standing systems seem to mist and if the room isn't large enough to keep the unit far away from the bed (or curtains), it seems like a problem. The noise is also annoying. But moisture needs to be introduced into the air several months out of the year or it's unbearable, health-wise.

It's also not good for wood furniture which will get dry and crack if the humidity is too low. We monitor the inline system closely (HVAC inspections and cleanings, IAQ specialist inspections, and our own inspections). Still, I hate the idea of introducing moisture into the system like that. Do you have any particular inline humidification systems that you think are better, or worse, than others?

Are there certain things to be on the look out for? If I sent you photos of our system and where it's located, would you be able to weigh in on anything you might see that you could comment on? My husband and I so value your expertise and how generously you share your knowledge.

On 2021-02-08 - by (mod) -

Thank you for the follow-up, Sarah, that may help other readers.

Indeed among our plethora of odor source warnings is a reminder to look for odors being picked up at the return vent of an air conditioning or warm air heating duct system; such odors can then be transported throughout a building.

I don't know a perfect solution for humidification indoors, and myself prefer to do what I call "spot humidifying" - in very dry weather, where needed I might use a portable humidifier; among those I prefer designs that are most-resistant to bacterial contamination, such as steamers. though I've also used ultrasonic models.

Thank you also for the generous remarks; we've worked hard on this information for a long time so I'm particularly gratified when a reader finds it useful.

On 2021-02-11 by Sarah

Thanks, Dan ! I'll do a search using those key words for free-standing humidifiers. And if you have a specific brand and model that you like, and are comfortable posting it (not sure what your perspective is on that), I'd love it. It would give me a huge head start!


On 2020-09-30 by ian david boardman - Horrible smell in our bungalow - we're at a complete loss

We live in a bungalow. We have a horrible smell that appears without any warning and has no pattern at all. It is located in a corner of the bathroom. We have had a plumber (at least two) inspect and a drains company.

There are no cracks in the drain, they say its not a "sewage smell"

We have also had a Pest Company inspect and they say it not rodents.

We are at a complete loss as to what it can be. Its has not always been with us, just over the last year or so. It can disappear as quickly as it comes.
Can you assist.

On 2020-09-30 - by (mod) -

Ian

That odour is puzzling I agree. On this page you will find several strategies for tracking down an odour to the source.

Check out those suggestions near the top such as 6 steps in order diagnosis, and further down the page you'll also find a link for an odour diagnosis log sheet that let you record information over time that may help you pinpoint the order source


On 2020-09-03 by Anonymous - We ran 2 ozone machines in our house to get rid of Covid and now we have residual smells.

We ran 2 ozone machines in our house to get rid of Covid and now we have residual smells. What should we do?

On 2020-09-03 - by (mod) -

Anon

Please see our detailed advice on this common problem, found

at OZONE AIR PURIFIER WARNINGS

https://inspectapedia.com/sickhouse/Ozone_Air_Cleaners.php


On 2020-07-13 by Mif Mif - Every nightd at the same time a nasty chmecial smell comes from outdoors through our windows

We are assaulted every single night, around the same time, (and at times during the day) by a nasty powerful chemical smell coming from outside the windows.

The smell appears to be that of heavy street recreational chemicals, almost like burnt plastic with deep nasty tar tail stink. It upsets our respiratory and nervous system heavily, we have immediate headaches and nausea, irritability and other very unpleasant and disabling symptoms.

We are often forced to sleep in our car, although we pay rent to have a place to sleep...

We found no support from our landlord, who says odors cannot be traced or fingerpointed at. We are very frustrated, feel helpless and we do not know how we can solve this problem.

Relocating is NOT an option in our case, for the time being.

Important: the smell seems to defy wind when it rises at evening time.
Last night we had 30 mi/hour, we live 1/4 mi. near coastline, plenty of ventilation at a times.

Yet this odor arrives.
Our unit is very simple, relatively new and well supervised in its structure. Well Maintained.

We have already excluded ducts, A/C, etc.
The building is concrete finished.

The odor is very different from car fumes, ocean well tracked odors, or garden/fences/etc.

The garbage is enclosed in a building and very well disinfected.
Our house is a surgical room. Especially nowadays....

This problem is so big and compromising to our wellness and domestic peace, that it is leading to partnership rethinking in our marriage. Every night I have to help my husband to lock our place, escape or even just stay clear with our minds to make it to the car and run away.

If you, whoever you are, can suggest effective ways to further identify, trace, and neutralize/ eliminate this monster problem, or what source we can access for help, solution, PLEASE HELP US NOW. reply at symplegmaa@gmail.com
THANK YOU, VERY MUCH.
Mif

On 2020-07-13 - by (mod) - nasty powerful chemical smell

Mif

First read

WINDOW OFFGASSING ODOR COMPLAINTS, FIBERGLASS & VINYL 

Then, we have some specific odor store tracking diagnostic suggestions at the continue reading article link suggest just above. Please take a look at

ODOR DIAGNOSIS SIX STEPS

And don't hesitate to post your findings or follow-up questions


On 2020-06-22 by Patty - Very strong toxic smell

Moved into a 1 year old apartment. Very strong toxic smell upon entering unit. The smell permeates and sticks to clothing. Can not locate source of odor. Property management completed ozone treatment without resolution. Can testing be done on clothing to determine source of smell? Any other suggestions to determine if the odor is creating a health hazard?

On 2020-06-25 by (mod)

Patty

Unfortunately an ozone treatment sometimes makes the smell worse by oxidizing materials, particularly if the ozone is overdosed. Look in the ARTICLE INDEX at the smell patch test kit as a good way to track down orders to a surface or a source


On 2020-06-07 by Allan

Metallic, stale and musty smell. New tenant complains, old tenant did not. Airing out the house did nothing, tested for mold, checked plumbing, dry attic. Westlake Village, Ca

On 2020-06-07 - by (mod) - Metallic, stale and musty smell.

Allan

Individuals' sense of smell varies widely among people and even in the same person depending on health and other factors,and the strength of an odor in a building also varies widely, even when the odor source remains the same, as building conditions of air movement, fresh air ventilation, use of HVAC systems, temperature, humidity, even barometric pressure all vary.

If the odor is confirmed at the property enough that it is likely that there really is an odor (not an occupant health problem) then you need an onsite inspection and investigation to track the odor to its source.

A number of steps you can take to do that as well as an odor-log that can help are described in the article above.


On 2020-05-17 by Mark - smoke smell is driving one of our tenants crazy

Smell smoke in one of our units everyone indicates they do not smoke. The smoke smell is driving a person in one unit crazy and she says the smoke is effecting her health

On 2020-05-17 - by (mod) -

Mark

If we assume for now that the smoke smell is definitely from tobacco products, and if the odor is confirmed by multiple occupants - so as to indicate it's not a neurological or health disorder on one individual's part - then further investigation is warranted.

IN that case look for odor transport pathways - ducts, stairways, elevator shafts, ventilation systems, even openings in floors and walls for routing of wiring or piping.

Keep me posted.


On 2020-04-30 by Jerry Rusin - smells in a new home after laundry room flood?

Hi, I sincerely hope you can help us. Our home is only 18 months old. 2 weeks ago we started developing an odd odor from the back 4 floor heating vents going out to our garage and in the laundry and back bathroom. Best description is bad dirty sock smell.

Around that time we had a small flood in the laundry room from the wash machine and water probably went down the laundry floor vent into the main ventilation trunk feeding the back vents.

I looked at the vents feeding the main trunk and nothing in them...took pics with phone. Had the furnace guy out and he says the furnace is fine and not the cause of the smell. Today a spent a bunch of money and had the vents completely cleaned out, vacuumed, and deodorized....and even before they left the smell was back. The main trunk in synthetic...not metal...

.is it possible the main trunk material is wet and causing the smell? We are beside ourselves at this point and actually concerned about the health risks of what we are breathing. Do you have any idea what is the cause of the smell orr have any suggestions?? any leads would be appreciated. Thanks

On 2020-05-01 - by (mod) - track down odor in a new home

Jerry

First: follow the water dfromp that leak. See what got wet - drywall? insulation?

Is there mold in building wall, ceiling, or floor cavities? Make some test cuts and take a look.

If you don't find an obvioius leak-related or mold-related odor source, THEN try the procedure we give at

ODOR DIAGNOSIS SIX STEPS

proposes taking an orderly approach to tracking down the source of an odor; that might be helpful to you.

About the"dirty socks" smell, there are some mold genera/species whose MVOC's are described just that way, so you could be on the trail of a mold odor source, which would make sense if the odor problem followed a flooding event.

Besides the article I suggest above, if you are confident that the odor was never present before the flooding event, then follow the water.

Finally, yes, some fiberglass-mat type ductwork can, though treated for water resistance, harbor mold after having been soaked.

Try our SMELL PATCH TEST KIT (see the ARTICLE INDEX) to confirm that that duct material is an odor source and if so, it cannot be cleaned, and IMO sealing its surface is an unreliable bandaid - I'd replace it.

On 2020-05-06 by Jerry

Thank you for your thoughts. We are positive the odor is from the main trunk of the ventilation duct into which
water from the laundry room drained.

We were wondering whether the odor could just be wet ventilation material that should dry out over time or whether it is from a mold. I am going to use a self stick to take a picture of the inside of the duct to help to decide if it needs to be replaced as you suggest. Thanks again. jerry

On 2020-05-07 - by (mod) -

If the interior of the duct system is lined with insulation in that has been wet I would not expect simple drawing to be adequate.

I'm concerned that there's already a mold infestation problem. It's not that the mold particularly likes fiberglass but rather likes the organic materials in and on the fiberglass insulating panels. You may need to replace that section.


On 2020-03-10 by Frog - how do I block odors coming from a hole at our electrical conduit or water pipe?

I have converted a stone barn built in 1848 into a house. For hundreds of years the barn housed cows and other animals.

In a utility closet there is a hole in the concrete floor where all electrical conduits and pipes enter the building.

There is odor coming from the hole. I believe the odor relates to the animals having lived there for so many years.

I no longer need access and would like to fill in the hole to block the odor. However, because of all the conduits and pipes, the fill needs to be a liquid solution such a wet concrete. Is concrete a odor blocking solution?

On 2020-03-10 - by (mod) - use a fire-rated foam sealant as an odor block in a concrete floor?

Frog

I would consider a fire-rated or "FireBlock" Foam spray sealant - thus not encasing wires in concrete and causing a lot of trouble for someone in the future. An example is shown below. Check with your local electrical inspector.

On 2020-03-11 by Frog

Mod:

Many thanks for your advice. I will try the Foam solution. It will be much easier than filling the hole with cement (access is limited). If the odor persists, I can always remove the Gfoam and try something else. Thank you!!




...

Continue reading at ODOR DIAGNOSIS SIX STEPS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see ODOR DIAGNOSIS FAQs - questions & answers about finding the source of smells & getting rid of or blocking smells & odors in & around buildings

Or see these

Recommended Articles

Suggested citation for this web page

ODORS GASES SMELLS, DIAGNOSIS & CURE - home, at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING ODOR DIAGNOSIS & CURE

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