Building odor & smell diagnostic FAQs:

Frequently asked questions about how to track down the source of odors or smells in or around buildings. Where is that horrible smell coming from? Is it the dog? Maybe not, as these reader questions and moderator replies explain.

This article series provides a methodology useful for tracking down the sources of odors in buildings. How to find the cause of odors, odor sources, and how to find and cure the source of smells in building air, water, heating and cooling systems, or other sources.

More FAQs on Finding the Source of Odors or Smells in Buildings

Recent Questions & Answers about Odor Diagnosis & Cure in and around Buildings, posted originally

at ODORS GASES SMELLS, DIAGNOSIS & CURE - topic home - be sure to check the procedures and advice given there.

On 2016-06-09 by mod) - bad smell coming from crawl space

Steph you need an on-site expert to look with care in the crawl area, to study the history, construction materials, and other conditions of the home, to identify the most-likely odor types and sources, and to dig more deeply into those areas to find and remove the source.

Beware of sewer gas leaks and odors as such are potentially explosive.

In this article series we make suggestions for tracking down odors to sources and fixing them - the "fix" of course depends on the source. I can't guess at the cause of your problem from a brief e-text.

Keep me posted.

On 2016-06-09 by Steph

We bought a house about 4 years ago in Long Island, NY. It's a expanded brick cape.

We noticed right after we moved in that there is a really bad smell that comes and goes when it's humid and when it's about and during rainy days.

It's mostly by the entrance, there's is a crawl space under need it but the smell down there it's totally different. The smell can go to the living room but now we can feel it in our bedroom. My husband and I had never smell this before. Please help

On 2016-05-03 by Anonymous - nasty smell around my boiler

There is a nasty smell around my boiler cupboard and downstairs toilet shower room any suggestions

On 2016-04-30 by susanharper52@yahoo.com

I had blyss electric radiators installed in my property, but I cannot get rid Of the odour that comes from them, I have been told that it is the oil they put on them at the factory, I have gone out put them all on opened the windows but when I get back there is such a smell in the flat

On 2016-04-27 by mod) - An ammonia smell from chimneys

Intruder,

An ammonia smell from chimneys is not one that's familiar to me. I wonder if there is or was a dead animal in the chimney or wall.

Possibly animal urine?

If the plaster smells you may need to remove it, remove any contaminated insulation, clean and seal the framing, then repair. But you might want to try a shellac or lacquer primer sealer top coat first.

On 2016-04-27 by Intrudermelodie@hotmail.com

I have been looking for help but can't seem to find my problem any where. I had no cap on my chimney and lived here since 2005.

Now I get an ammonia smell imitating from the chimney in the attic room. I found out it was from chimney that got wet and was seeping through the plaster covering on the chimney.

I had a cap put on but now don't know what to do. I scrapped all the crystals off with a putty knife.

But a piece of the plaster came off and there is crystallized ammonia under it on the chimney itself. Do I take that all the plaster off to clean it?

Or do I just scrape it down and then clean the plaster? Do I replace the plaster if I take it off, or do I leave it the way it is with out covering it?
Please Help
Confused home owner -

On 2016-04-24 by Marj

I have a rent house and my tenants have complained about a septic smell. We are on a city sewer system.

I have had the following test performed; camera, smoke and water all of which came back negative. my tenants father replace the wax ting in master camode since this is where they say the odor is the strongest.

The subdivision had a street smoke test performed due to other complains of "odors" but ours show no problems.

Not a peat trap,issue because all sinks and tubs in constant use. We've had a lot of rain resently and the say the order is back. Other possible outside causes; man hole cover in back yard, meat market two doors down.

My plumbers actualy approached market inquiring when the last had their grease trap cleaned but they would not speak with him. Plumber had said he could smell odor from the top of the house.

Thinking it was coming from market. I've replaced front door and large sliding glass door trying to make home more air tight in case it was coming from outside(meat market)I'm at a loss for what to try next.

On 2016-04-23 by Sarah

Sorry, forgot to mention, cleaned the fridge out too and the drip tray and it wasn't that.

Our house is old but fully renovated 5 years ago and shares a party wall. 3 weeks ago we started smelling this strange sour, damp smell in the kitchen whenever we used the range hood. We have a plumber come and he pulled it apart and the smell wasn't coming from there. It exhausts through ceiling which we went into and can't find source.

We haven't used range hood or stove for 3 weeks now and the smell is still here. Comes and goes. It seems to be every where along back kitchen wall (party wall) including under the kick boards.

Our neighbors don't have it. If we don't open the house up, it travels through the whole house.
The smell is like sour milk, sour vomit,

Damp. Any ideas? Can't live like this!

On 2016-04-20 by Anonymous - So first I can try Clorox in the drains

So first I can try Clorox in the drains, if the mold is in one of them?

Then second, I'm thinking the dry traps would be in the "hardly used" bathroom? How do I remedy that?

Then third, go up on the roof and check the vents?

Fourth, check the ducts?

Since I'm 74, I'll probably let someone else do numbers three and four, but I'd appreciate any advice on how to proceed with one and two, assuming the Clorox won't harm anything (the house is 40 years old).

On 2016-04-20 by mod) - If you smell mold, there's usually mold somewhere.

If you smell mold, there's usually mold somewhere.

(No mildew, that only grows on living plants and it's not particularly smelly).

I'm not able to know the connection between upstairs bath and the downstairs complaints but it sounds as if there may be dry traps or a bad plumbing vent or a leak into the HVAC ductwork.

Vinegar is a nice mild cleaner but won't remove a mold problem nor a drain clog.

On 2016-04-20 by paul

I live in a two story home that has two ac/heating units (upstairs and downstairs).

There is a mold/mildew odor that happens when someone takes a shower in the "upstairs master bedroom shower".

The odor however, occurs downstairs, and seems to be coming from the "downstairs ac/heating vent" located in the family room (which is directly underneath the master bathroom). The upstairs bathroom does not have an exhaust fan,

and I cleaned the shower and sink drains using hot water, baking soda, and vinegar. This helped for about a day or so, and now it's back. Another clue that may help, is that there is another bathroom upstairs which is rarely used. I did the same thing to the tub and sink in that bathroom on the same day as the one in the master.

I understand that unused drains can dry out and cause gaseous odors. All of them drain quickly (sinks, tub and shower),
How do I proceed from here?

On 2016-04-01 by mod) -

Anon:

One cannot guess at the possible health risks of a sprayed chemical without knowing what the chemical is and what is or was your exposure level to the chemical by contact, airborne spray droplets, or VOCs or other offgassing from the chemical.

Sometimes a characteristic odor can help guess at what chemical herbicide was used. For example a "burnt vanilla" odor might describe Gowan's Sledgehammer herbicide granules that contain Halonsulfuride, methel, but I am NOT suggesting that that's what your landlord used. We don't know.

My OPINION is that offgassing from heavily-applied herbicides might be harmful. You should ask what product was sprayed, review the MSDS for that product, and discuss your worries with your doctor.

On 2016-04-01 by Anonymous

We live in a one floor 4- plex. The landlord sprayed a herbicide outside. Ever since then (now 3 days later) we have a terrible chemical smell in our apartment. It seems to be the worst in a front corner bedroom. The outside wall of that bedroom is right along where spray was used. I am allergic to some things and get bad reactions to different chemicals.

My husband doesn't have allergies but he can smell this too. It is causing us both to feel really bad.

One of the things I get is a terrible metal taste in my mouth, and head aches. The landlord was aware of my allergies and when we first contacted her about spraying she lied and said she didn't use it around our apartment, but finally admitted that she did in fact spray in spots by our place!

I called a hotline to see if there is anything we could use get rid of this but wasn't given any answers. We really need some help here. Thanks

On 2016-03-17 by mod) -

Anna:

odors from natural gas, typically mercaptan that is deliberately added to gas so that people will smell gas leaks, mean that the building is UNSAFE. If it's a gas leak, get outside and ask for help.

Pee from animals or poop from animals smells nothing like mercaptan added to natural gas. Find and clean up the pee, poop, or dead animal.

On 2016-03-09 1 by Anna

I woke up to a strong oder that smelled like natural gas which I heat with. My pilot light to my gas logs was burning. I open the storm to let the fumes out and a blast of oder came inside from a terrible stench on my front porch. It smelled like fresh cat poop or pee from a possum or skunk. How do I get rid of this odor ?

On 2016-02-26 by KD Lee

I have moved 6 times in the past 3 years. I even moved 1000 miles away, but I am still getting these odors in my home and car.

They want to expose me to these chemicals until my immune, system can't handle it. I think someone is intentionally doing this and the only reason I can think of why is insurance. It must be a huge policy because they spare no expense. Following me everywhere I move. I need proof of this to get help. Any ideas?

On 2016-02-02 by Kevin

I have exposed 4" x 10" decorative wood beams spaced 24" apart in the ceiling of a bedroom.

The rest of the ceiling is tile and concrete, no organic material up there, just the wood beams. These beams were subject to several years of occasional roof leaks that have now been fixed.

ast roof leak was 3 months ago. The leak has been fixed but the moldy smell persists. I know it is the ceiling because I temporarily sealed off the ceiling with poly and tape. Smell disappeared immediately but after a week I had to remove the poly for asthetic reasons. Smell immediately returned.

Any suggestion on how to cure this. I have been running a Dehumidifer day and night for 3 weeks with little improvement.

Help!

On 2016-01-17 by Doug

We have a "chlorine" smell in the garage. Oddly it is on the side of the garage where no paint or cleaning products are stored.

The hot water heater and furnace / blower are in the garage but the smell does not seem to be coming directly from them? There is a kitty litter that has never produced this smell and the smell remains after cleaning it. The cars have been removed and the smell remains..any helps is appreciated.

On 2016-01-09 5 by mod) -

Sorry, I'm baffled too - too little information; Figure that although you may smell an odor in the absolute center of a space, it has to come from somewhere - either from a heating or cooling system, or from a surface or from something that is in the room. That's why I suggested using our SMELL PATCH TEST PROCEDURE to isolate probable sources.

On 2016-01-09 by Anonymous

The oder is in a center room no hook ups for gas.what could it be?

On 2015-11-19 1 by mod) -

Q
good progress in that you've isolated to a specific room.

There is no "air test" that can screen for all possible contaminants, though there are a few broad spectrum tests used by fire fighters. I've also had trouble ordering sophisticated air analysis tests that cost upwards of $1000. - lab expertise and results varied widely in usefulness.

Look by eye and nose for candidate sources.

On 2015-11-18 by Q

There is one bedroom in our house that when the door is closed (which we are doing now so that we do not have to heat it) there is a very strong acrid/chemical smell that when it is closed for a long time it will sting your eyes. I am going to try the smell patch test to see if it is a specific item, walls(paint), windows, carpet, doors, etc. but as for now it is so strong everything smells like it.

have a very sensitive nose and the fact that it will also sting my eyes really concerns me. Is there any type of "commercial air test" that can be purchased on the market?

Whatever it is will permeate and stay with clothing that is in that rooms closet until washed away.

I tried just hanging items in the outside breeze for over an hour and it did nothing to help. Please advise.

On 2015-08-28 by Josh

We recently purchased a home. During the purchasing process there was a bit of a smell in the house that gave us some adverse reactions, itchy throat, headachy feeling. The smell has always seemed to be residuals from air fresheners or a cleaner and the house had been empty and closed up for a few hot weeks.

So we thought and were told that it would just air out and there wouldn't be any issue. Seemed logical.

The inspection came back clean and we have since had a mold inspector come by and have a look.

He did not do a mold air test as he didn't see any reason to. He did however comment on the chemical smell in the home right when he walked in and feels that VOCs might be the issue.

Also, the inside of the house has been painted and the floors cleaned. We have had fans going, all windows open and three strong air purifiers running for two weeks now. However, there is still the chemical air freshener-like smell. You can even smell it when walking up to the front door.

We are also still experiencing the effects; sore throat, swollen nasal passages and glands, and headachy feeling. It has gotten to the point we are not able to occupy the home for very long, let alone sleep there.

I've talked to multiple environmental groups and they are at a loss.

Any thoughts you might have would be greatly appreciated.

On 2015-07-29 by mod) -

Kathy thanks for reporting the trouble. The links worked for me but I'll keep an eye on them.

See https://inspectapedia.com/odor_diagnosis/Odor_Diagnosis_Steps.php

ODOR DIAGNOSIS SIX STEPS - this link is now working properly

On 2015-07-28 by Kathy Nordine

I've looked at the instructions once for your odor detection test that used tin foil and paper toweling a few months ago. My undetected odor has persisted since January.
That said, I cannot locate - or, actually "get to" the step by step instructions for this test.

Each time I click on a link that says "odor detection test in six steps" all that happens is it takes me back to the same page, where I again click on the same link, etc. etc.

What am I doing wrong? Or have you actually taken the test off your site?

On 2015-06-17 by mod) -

When it's hard to identify an odor we of course don't know how to remove its source. Rather than focus further on tracking down broccoli odors (think mold, chemical spill, other), I'd try to home in on the source. Check the HVAC air handler, ductwork, filters, etc. for some visually obvious contaminant or leak source

OR try doing some cleaning there to see if that makes difference. Keep in mind that an AC unit can pick up an odor at its return air inlet and then distribute it to elsewhere in the building.

On 2015-06-17 by Elizabeth

There is an odor in my house that smells something like cooked broccoli. It's been around for months; seems a little worse when the air conditioner is running. We've checked for dead animals; also mold. Any recommendations?

On 2015-05-28 by mod) -

Jill try out the EXPERTS DIRECTORY link at page top.

On 2015-05-27 by Jill

Five years ago I remodeled a room in my house, I work from home and purchased this property with the intent of adding new office space.

I a completely built a existing room from studs in. I used the space daily for 10 months from July to April, it was in April I started noticing an odor that made me very sick, my sinuses were raw, my teeth hurt, I would get lightheaded, and have to leave

. It seams to come and go at will, but there 75% of the time. Still today I find it very difficult to work in there. It causes headaches, dizziness, I become tired, I'm located in north central CT if you can re commend someone who could figure out where this is coming from. I've removed electronic equipment, purchased a new copier, took out rugs, and still no help. Please any advise is welcome.

On 2015-05-13 by mod) -

Karen:
Acetone has a very specific odor that many people can recognize. By no means would I assume that the fire department's instrument tested for that volatile substance. I'd be looking for a nearby chemical spill, leak, or substance, even paint cans.

Freezer as a source: possibly if condensate is leaking or mold has formed. But refrigerant gases themselves are generally odorless.

The fact that you smell the odor specifically in the sump pit suggests that that's the source. If I were on-site I'd be investigating how and from where water enters the sump pit and tracing that backwards.

On 2015-05-05 by Anonymous

Thank you Mr. Friedman. I will ask maintenance to periodically check again for moisture in the walls.

On 2015-05-01 0 by mod) -

Fresh air ventilation can help if no source has been identified, but keep in mind that if outdoor humidity is high there could be an indoor moisture issue. Just circulating air may make matters worse.

On 2015-05-01 by Lisa

3 weeks ago I started smelling a pungent lemony smell in the space behind my bed between the bookcase headboard. It is worse when the sun hits the outside wall my bed is up against. It is stronger if the house is closed up even for an hour.

Apartment maintenance has been out twice and there is no moisture in any of the floors or walls in my apartment. I haven't spilled anything back there and have pulled out all the drawers to check for odors and there are none.

I even lifted up the mattress to check for issues and there are none. The smell is only in that area and maintenance doesn't know what to do. They think it could be coming from somewhere else and just pooling behind my bed since that is really the only place that doesn't get consistent air flow. I keep a fan running to circulate the air which helps some. I'm at a loss as to what to do. When the odor is strong it gives me headaches. Maintenance is now just waiting to see if it improves. I'm not inclined to wait. Any suggestions would be appreciated. Thank you.

On 2015-04-30 0 by Karen

We all of a sudden have a horrible paint-like / acetone smell in the basement. It seems to be the strongest at and possibly coming up from the sump pump and a crack in the concrete by the sump pump. We have removed all paint cans / chemicals of any type from the basement; nothing was open or leaking. We had the fire department here. Their gas gauge thing did not register anything. They said it works for 5 different types of gasses.

Their only suggestion was running a hose into the pipe of the sump pump and flushing it out. We did that and have had no change whatsoever in the smell. It is so strong it takes your breath away. We are at an absolute loss as to what this could be or even what else to look for.

We do have an old deep freezer in this same corner that seemingly is still working just fine, but we are questioning whether it could be coming from this. However, that doesn't explain why when putting your face right over the sump pump opening you get blasted with the smell. We tried opening the basement window and then turned on our attic fan to try and air it out, but this only made the smell worse.

And if you put your face over the sump pump opening with the fan on, you literally will get blasted with this horrible smelling air. We built our house 10 years ago and know that nothing is buried underneath it. Again, we are at a complete loss and would appreciate any help or insight anyone might have!

On 2015-04-27 by Larry

Thanks dan joe Friedman, Ithanks for the suggestions I'll tty them out.

On 2015-04-23 by mod) -

Larry,

I'd do some swab sample tests to find out if there was a prior sewage backup - unless you can find that out from those who know the building history.

On 2015-04-23 by mod) -

Re-posting with non-functional advertising link

Rob said:
Hello!

I live in a building downtown with backyard and other buildings surrounding us.

The last 3 years we've had an problem regarding a sound that comes from outside:

You can hear the sound on the link provided.

The sound is annoying and sometimes we cant sleep when our bedroom windows are open. Anyone know what source this sound may be coming from? We have had no luck identifying it yet.

On 2015-04-23 by Larry

Question
I have a small 1story office building situated on a crawl space, it's about 1200 soft. There is an awful mildewy, garbage, pungent smell that comes and goes. It seems to be more prevelant after rain but also comes during dry weather. The smell is very puzzling and extremely aggravating.

We have recently cleaned the crawl space out so there's Nothing down there. Any suggestions on causes and or solutions would be greatly appreciated. Please
help!!

On 2015-04-15 by mod) -

I suspect either a blocked or leaky plumbing vent or a leaky toilet seal.

On 2015-04-15 by Anonymous

We have 5 bathrooms in a 2 store home, it's build on a crawl space, using a septic system. The problem is the toilet in the powder room & the toilet in the master bath room on the main floor on opposite sides of the house.

They don't always smell; but when they do, it is a very strong smell/odor like a public bathroom. The two bathrooms are in use daily so a try drain shouldn't be the problem. None of the bathrooms upstairs smell.Two of the bathrooms up stairs are in use, but less frequent & 3rd. one seldom.

The 3rd. up-stairs bathroom is located close to the powder room downstairs, but on the other side of the house from the master-bath room. We had the septic tank pumped last fall, so that is not the issue. What could be the causing of this problem?

...

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

Or see ODOR DIAGNOSIS FAQs-3 - more recent Q&A on finding and removing odors in and around buildings

Or see these

Recommended Articles

• ODORS GASES SMELLS, DIAGNOSIS & CURE - home
  • ODOR DIAGNOSIS CHECKLIST, PROCEDURE
  • ODOR DIAGNOSIS SIX STEPS
  • ODOR EVENT LOG & CHECKLIST FORM [PDF] - Use this form to collect data to help track an odor to its source
  • ODOR EVENT / SOURCE LOCALIZATION LOG

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