How to find & cure the source of animal or human odors:

Pet / animal urine or other odor diagnosis & removal in buildings starts with finding all of the smell sources & causes.

This article series provides suggestions for finding and removing animal or human odor removal from building interiors, building exterior surfaces, from soils around buildings or from urine-odor smelly clothing, bedding, and other soft goods.

We discuss how to find where animals are getting into your building and how to keep them out, including bats, birds, rats, mice, and squirrels and even raccoons. We explain the use of a black light or UV light to find the location of human, pet, or other animal urine and we describe the use of UV lights in forensic investigations.

This article series includes lists of products & formulas for odor cleaning or smell removing chemicals, washes, products.

Pet Odor Guide

How to Find, Test, & Remove Pet Odors, Pet Odor Detection, Cat, Urine, Dog Urine, Bat, Bird, or other Animal or Human Smells in Buildings

This article series begins here with help on finding the source of urine or animal smells at or in buildings, we give advice concerning the detection and removal of animal smells & odors from dogs, cats, or other pets.

[Click to enlarge any image]

This article series focuses on removing pet or other animal odors from buildings due to pet urine, pet feces, wild animal urine, or even human urine on and around buildings or on clothing and other soft materials.

Cat allergen and odor source identification, testing, removal, are also discussed beginning at Cat Dander: how to inspect and test a building for past or current presence of cats, cat hair, cat dander, and cat allergens".

Pet Allergens.

Animal smells in or around buildings, both indoors and outside, may be due to current or prior pets in a building, pet urine or fecal waste, cat boxes, animal hair, dog dander, cat dander (are allergens and are indicators of the level of prior pet activity), dust tracked in by dogs.

The little stuffed animals in this photo include a skunk - both were innocent of any pet-crimes, but they had been placed at either side of a basement door jamb to cover stains from basement water entry.

Prior flooding in buildings or prior sewer backups can lead to hidden bacterial or mold reservoirs that are both an odor source and a potential health hazard.

Suggestions for Finding the Source of & Removing Animal Odors Indoors

Start with advice on how to find the source of pet or other animal odors, including urine odors

• Determine that animals have previously been in the building 
  
  even if there are none there at present. Look for scratches, stains, and odors as we describe below.
  
  Pet doors and fences also tell the history of the type and size of pets that have been in a building.
  
  Also see BLACK STAINS from ANIMALS for a description of the cause and cure of various types of stains caused by pets or other animals in buildings
• Follow your nose -
  
  often pets were confined to particular rooms or areas of a home
• Allergic reactions -
  
  of people to entering or spending time in a building may be due to the presence of animal hair or more likely animal dander from dogs, cats, or other pets.
  
  Also see FIBER & HAIR IDENTIFICATION
  
  A carefully selected dust sample from a building is an easy screen for the presence of animal dander including dog dander, cat dander, evidence of rodents, dust mites, insects and other allergens.
  
  Where appropriate, other chemical assays for allergens are also present, but we advise against ordering costly tests that may risk inaccuracy if the sample itself is not selected by an expert.

• Use your eyes - you may see pet scratches on one side of a door (photo at left), telling you where the pet was sequestered. Also look for teeth or claw marks on window sills, door trim, stair parts, flooring baseboard trim, or any other component that an animal may be able to bite or gnaw.
  
  Pets shut into a room may urinate in that space, particularly near a door leading to outside or around a large piece of furniture, or if territory marking, often against a wall.

• Look outside too for Bats, Birds, Rodent Entry Points - 
  
  if your building has been invaded by bats, rats, mice, squirrels, or other wild animals, you should inspect both indoors and outside for openings or stains and marks that indicate points of entry and exit for those creatures.
  
  Details about this topic are found
  
  at ANIMAL ENTRY POINTS in BUILDINGS.
  
  Watch out: before sealing up a hole in a soffit or wall where squirrels or bats are entering your building, make sure the animals are not going to be trapped inside where they will be mad, frightened, hostile, even dangerous (like a rabid raccoon), or ultimately dead and another source of stink.
  
  Consult with a pest control professional who may have a practiced eye at spotting where animals are getting into your attic, roof, walls, basement, and who may be able to provide a repellant that will at least temporarily drive them out - alive.
  
  While there are no bat control poisons currently approved in the U.S., we have found that moth balls (naphtha) are an effective repellent for bats and squirrels, though naphtha odors are also repellent to some humans.
  
  Watch out: also for wild animal bites, bacterial and viral hazards when entering confined spaces where invaders are or have been present.
  
  The author (DF) became temporarily ill after (foolishly) working in a "clean looking" crawl space that later we realized had a heavy contamination of fecal and urine contaminated mouse dust. Bat and rodent droppings as well as bird droppings can be a source of a pathogen potentially dangerous to humans, the fungus Histoplasma capsulatum.

• Birds in the Roof Structure or attic 
  
  may be entering through a hole they managed to peck in a roof overhang or soffit such as shown in our photo at below-left.
  
  Birds in the Attic at infestation levels may be obvious if you spot bird dropping stains such as those shown on our photo (below-right)
  
  Details about this topic are found
  
  at ANIMAL ENTRY POINTS in BUILDINGS.

Above: Bat drooppings on a beam in the attic of an older New York home.

Below: dog pee stains have penetrated this hardwood floor, as was discovered when carpeting was removed.

• Look for stains 
  
  on floors or walls, where pets urinated or marked spaces;
  
  The dog urine stains (dark spots on the wood floor) in our photograph just above went un-noticed until the property owner removed smelly carpeting and carpet padding.
  
  These stains, leaving both visual and olfactory mementos of the perpetrating pet who was long departed, cannot be removed by light sanding - flooring replacement would be necessary as the stains were deep into the wood.
  
  The owner elected to re-seal the floor against odors.

• Look below smelly carpets
  
  as often urine has soaked through carpets, carpet padding, and has entered the subflooring or finish flooring wood materials.
  
  In this urine-stained corner we found that the pet urine had penetrated carpet padding as well.

• Look below vinyl sheet flooring and vinyl floor tiles 
  
  in an area where pets may have urinated.
  
  Readers have reported finding pet urine that had soaked into backer material or even cardboard or paper underlayment that had been placed underneath vinyl floor tiles.
  
  A reader reported that on pulling up the laminate portion of flooring they found pet urine-soaked paper backing material that had remained glued to the subfloor.
  
  The urine pattern was found around the perimeter of where a bed had been placed - the pet had urinated repeatedly on flooring around, but not under, the bed.
• Use a "black light" or UV-light
  
   to look for pet urine even where no stains are visible.
  
  Small black lights are available from pet supply stores, art supply stores, and forensic and police equipment suppliers and are generally inexpensive.
  
  Both plug-in and more convenient battery-operated black-lights are available. Use the black light in dark or near dark conditions for the best view.
  
  Urine will shine a bright yellow color in this lighting.
  
  Details are at UV LIGHT BLACK LIGHT USES.

Above: dead mice found by the author (DF) when he looked on the upper side of a suspended ceiling tile.

• Also check for dead animals 
  
  in building attics, crawl spaces, wall or ceiling cavities and in duct work or air handlers or chimneys.

  Animal odors in buildings can occur when an animal such as a mouse or rat has died in a building cavity.

  A dead animal smell has been described by our clients with a wide variety of terms ranging from a vague noxious stink that seemed to vary with humidity to a sweet sickly smell.

  Dead animals or even insect nests in building plumbing, especially building vents, can also produce unexpected sewer odors - see Septic and Sewer gas odor links discussed below.

  Rodents, especially in the HVAC system such as air ducts, may also be a bacterial or Hanta virus hazard.

 

Advice for Keeping Mice and Rats and Squirrels out of Your Home

Pest control experts recommend several simple steps that will discourage mice and squirrels from moving into your building as they are inclined to do particularly at the beginning of cold weather:

• Housekeeping: 
  
  clean up spilled food, seal food in rodent-proof containers
• Pet food:
  
  we found that storing open bags of cat or dog food invited mice into the same area, a problem solved by keeping those large pet food bats in a small metal covered garbage can. We also stopped leaving pet food in bowls overnight.
• Garbage:
  
  garbage and trash cans should be made of metal and kept closed; clean up any spilled garbage around your trash cans both indoors and outside.
• Seal Building openings:
  
  as we discussed above about bats, look outside for openings into the building such as at soffits or roof eaves, especially near overhanging or close tree branches (squirrel highways), and close to the ground look for openings into the basement at vents, windows, or building sill plates and siding bottom edges.
  
  Seal these when you won't be trapping animals inside. We have read that mice can enter a building through openings as small as 3/8"!.
• Trim shrubs at least a foot away
  
   from the building walls; we prefer 18". This also reduces the attractiveness of the building to insect pests such as termites and carpenter ants. If your home is in an area where Norway rats are a problem, keep low growing shrubs away from your building walls entirely as those rats burrow under them, especially Junipers and Taxus.

If your building odor complaint source is found to be outdoors,

see URINE ODOR REMOVAL at BUILDING EXTERIOR.

This website provides articles on to diagnose, test, identify, and cure or remove a wide range of obnoxious or even toxic odors in buildings and in building water supply.

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, plumbing drains, plastic or vinyl odors from building products, flue gases, oil tanks or oil spills, pesticides, septic odors, sewer gases, and even abandoned chemicals at properties.

At URINE ODOR REMOVAL at BUILDING EXTERIOR we discuss the problem of odors outdoors on and around buildings and we list various urine odor products, chemicals, treatments.

At ANIMAL or URINE ODOR REMOVAL we describe how to remove smells & odors.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

How to remove odors from years of dog poop and pee indoors: still smells after washing and using an enzyme cleaner

I have a rental property that the renter let her dog poop and pee in the house for 10 years! Is the most rancid smell I've ever encountered.

I have removed all carpet, padding and subflooring. Washed the walls with enzyme cleaner and it still smells. Also used ozone generator 4 days. I cannot figure out why it still smells - On 2020-07-02 by Sheryl Senft -

Reply by (mod)

Sheryl

My sympathy - you describe a nasty and hard-to-cure odor problem.

Extensive demolition, cleaning, sealing may be needed to control pervasive pet odors in buildings:

In the article above I discuss this in the section "Reader Question: Animal or pet feces or urine odors: tracking down a rancid sweet wet paint odor in one room - suspected pet odors from urine or feces"

The most-egregious case that I know well involved a 1960's home that hosted many dogs over many years. Cleaning all exposed surfaces could not remove the pet odors: those penetrate even semi-porous surfaces like drywall and wood.

You say you removed the subflooring. Really? So inside we see just floor joists? Please clarify as that may affect my advice.

In the dog-smell house that I examined in detail I found very find and smelly dust inside wall cavities and even on the attic side of ceiling drywall.

Dogs played outside, rolled about, came in and over years a combination of organics from smells and actual physical dust particles even penetrated wall and ceiling cavities (generally at openings such as around receptacles and light fixtures) as well as the fiberglass insulation in those areas.

Only by gutting to the frame, removing drywall and insulation, followed by cleaning, followed by using a sealant, could we get the odor down close to zero.

Watch out: be sure to also

review OZONE MOLD / ODOR TREATMENT WARNINGS https://inspectapedia.com/sickhouse/Ozone-Treatment-Warnings.php

For sealants take a look at those discussed

at DISINFECTANTS & SANITIZERS, SOURCES

where we list suppliers of biocides, fungicidal sealants, and related mold sprays and cleanup products.

Odors got worse after our home was "cleaned and sanitised" - we're using an ozone cleaner

We have a bad odor emitting from 2 heat output vents. It has been present for several months. We thought it might be a dead animal but it continued. So we had the crawl spaces under our home cleaned and sanitized, but the smell returned shortly after.

Then we had HVAC company come for annual furnace inspection, etc.

The technician told us that everything was ok. But the smell continues.

We are presently using an ozone cleaner which helps, but doesn't seem to address the problem. What more do you suggest we do? Thanks. Ann Rice On 2017-01-07

Reply by (mod) - bad odor from heater vents

Watch out, Ann. Over-dosing with an ozone generator can cause severe new indoor odor problems as you can read by searching InspectApedia.com for OZONE WARNINGS

If no one has inspected the duct system there could still be a dead animal or some other contaminant in the duct system. Just cleaning the crawl area isn't a fix.

If your furnace is picking up return air from somewhere that is home to an odor source, smells may be getting moved from that source to your heating output registers.

Search InspectApedia.com for DUCT ODOR DIAGNOSIS for some suggestions.

You can also try searching InspectApedia for ODOR DIAGNOSIS to see more general suggestions for tracking down an odor.

There might be a dead animal in the wall - what do I do?

I bought a house and moved in mid-June. The bedrooms are carpeted so I steam cleaned them. There was never a smell until I had a cable TV line added to my bedroom: they came up through the floor/crawl space. Ever since there has been a smell of like rotting garlic.

Someone I told thought there might be a dead animal in the drywall, but it's been steady for a month - not getting better or worse. If it was a dead mouse seems the stench should last about a week.

Yesterday I was talking to a neighbor who knew the prior owners. He came into the bedroom and could smell it too. He said they had a cat that used to throw up a lot. I'm wondering now if the smell could be the vomit - that maybe with cleaning it seeped into any padding/subfloor and the cut into the carpet could be releasing scents that had been previously masked.

I know they had a plug in scented wax thing in one outlet that had spilled on the carpet: maybe they had been hiding smells all along. I don't know why it would wait 2 weeks or so to stink - seems that should have happened sooner - especially with the carpets having been washed.

But also, it's very hot and humid in this area of NC, so maybe in the somewhat cooler month of June when I moved in it wasn't noticible. Any other ideas? Before I have an animal carcass specialist come and cut out dry wall looking for bodies? - On 2016-07-27 by Lynn -

Reply by (mod) - dead animal in the floor?

Usually a small dead animal like a mouse dries out and stops smelling after weeks.

You don't give a time period but it seems to me that if cat vomit were a problem the odor would have been there before.

I'd focus on tracking down the odor to a specific spot or surface; try the SMELL PATCH TEST KIT (search Inspectapedia for that phrase) to see if that helps you out.

Reader Question: Animal or pet feces or urine odors: tracking down a rancid sweet wet paint odor in one room - suspected pet odors from urine or feces

What could be the source of an odor that smells like rancid, sweet, wet paint? The smell is contained to one room of our house, it builds up when doors and windows are closed, is all the time and we can't pinpoint exactly where in the room. We moved in 4 months ago, and it smelled.

We thought it was wet paint (previous owners painted) even after weeks and weeks and no other room (that was painted) smelled. We wound up gutting the walls down to the studs, replaced insulation, drywalled, and painted. It smelled like fresh wet paint, and when that dried we were back to the same offensive odor. We've tested for mold with an IH, tests were negative. Please help!!!

We are desperate, it's my youngest daughters room and she has been sleeping in her sister's room until we can figure this out! Thank you. Wendy K. 11/6/11

Reader comment:

Unbelievable Wendy but we seem to have the same thing going on in one small area of our house, a slightly sweet paint, disinfectant or perfume smell. We aren't sure which.

(We moved in 12 months ago and have looked behind the walls in the soffits and in the adjacent crawlspace and found nothing.) We have been ventilating the entire time but the smell is still there when we close the room up today. I am going to do the patch test next week. - Chris 11/18/11

Reader follow-up:

Hey Chris, did the patch test help you identify anything yet? Did the previous owner have pets? Ours had a big dog and after all our attempts, we are down to the floor.

We are thinking (hoping) it just might be an abundance of dog urine that soaked through the wood floor. My husband found a product at PETCO that addresses this, something specific for dog urine removal. It is kind of perfume itself but we doused the floor twice and are crossing our fingers. Good luck! - Wendy 11/28/11

We had a dog defecating and peeing and leaving it on cement in garage and tile in basement entry, so it's not discovering the cause but curing it.

One door frame and the door (as its' a set) was affected and will need to be replaced- but can the floors be cured of the odor? A company that was supposed to take away that smell came and failed to do so. I heard that putting pet product liquids for pet waste is another way to work on it. What would you recommend? - Elaine 3/8/12

Reply: pet odors in buildings and success with removing them: clean & seal surfaces or remove materials

Chris & Wendy:

Our experience is that dog urine can soak deeply into wood flooring, especially if the floor was covered by carpeting and the urine thus remained for a long time.

Odors from dog feces are usually easier to cure if the feces were on a hard finished surface, but feces dropped on concrete (a garage floor) or tile (grout joints) can leave oils and fluids that soak into those surfaces.

While commercial deodorizers can reduce the complaint, and some enzymes can actually break down organic molecules that are part of an odor problem, it's often the case that sanding, re-finishing, sealing, or even flooring or drywall and trim replacement are needed.

Elaine:

Where a surface is to be left in place, such as a garage floor, try using a commercial concrete or tile cleaner followed by thorough rinsing (vacuum up the rinse water if it's in a basement or garage that can't be hosed to outdoors. Then when the surface has thoroughly dried, if odors remain you may need to try coating the floor with a sealant.

Some of the fungicidal sealants used in mold remediation or odor-controlling sealants used in response to fire damage in buildings can cure the remaining problem.

Question: dead fish (dead animal? odors in the kitchen - how to locate a dead animal in walls or ceilings

There is an odor in my kitchen that is likely a dead small something.

I have looked behind refrigerator and stove, and removed anything that can be looked under. But there are floors under cabinets that would require carpentry to remove the shelf

....want to know that that is the spot before I begin. How can I identify the location of the odor? Is there any gadget for that? - Jane

Reply: try a borescope before destroying cabinets or walls

I'm not sure it'll work in this case, Jane, but try our

SMELL PATCH TEST to Track Down Odors (article link at the ARTICLE INDEX at the bottom of this article )
to see if that helps pin down the most smelly area.

I'd see if the odor can be traced to a drain line.

Also, look for a dead mouse or other dead animal under an appliance (fridge, dishwasher), or under a cabinet, or even in the walls;

Finally, you may find a local home inspector who has a flexible borescope that can peer into tight areas such as under cabinets either by snaking the scope through an existing gap or opening or by drilling a small unobtrusive hole such as i the top of kick plates below your cabinets or in walls where odors seem strongest.

An example of using a borescope is provided

at HIDDEN MOLD, HOW TO FIND.

Details about sealants for these applications are

at FUNGICIDAL SEALANT USE GUIDE.

Reader Question: Mold or dead animal smells: smell in the master bedroom closet lingers even after some demolition; attic mold is supposedly "dormant"

I hope you can help me . We have a 7 year old home and we have a smell in the master bedroom and master closet. Both are on the same wall (south)we have a real bad odor that we have never encountered before.

We tore out the carpet with no good results. We have mold in the attic above attached garage but not close to where the smell is. We were told this is dormant? dead? and not the cause of our odor problem.

I have put the smell patch on three walls and also put plastic insulation on the windows - Pat--Boo20@att.net

Reply: dead mold may not be; other places to look for mold as an odor source

Pat:

If the odor is a moldy musty smell, and considering that you found attic mold in the building, I'd look for a source of leaks or trapped moisture. Perhaps cut some small exploratory 2" x 4" openings in the drywall at the most-suspect areas to permit a visual inspection. Same if it's a dead animal.

I would not assume that "dead mold" is really "dead" - dormant mold, meaning mold growth on a surface that is not producing active growth, can become active seasonally with variations in humidity, temperature, light, and other conditions, and can outgas MVOCs at times - depending on the genera, species, and surface on which the mold is growing.

Also the fact that someone saw a significant mold reservoir in one building location should make us alert for the possibility of other undiscovered leaks and reservoirs to be found.

Take a look at MOLD / ENVIRONMENTAL EXPERT, HIRE ? to see if it seems justified to bring in an expert.

Also see MOLD in BUILDINGS Procedure: what mold is often found where in buildings - simple technical presentation

Reader Question: problem with raccoons in the attic

We have NO ODOR. However there have been raccoons in the attic & I want to get someone to test the air quality for allergens related to the raccoons having lived in the house/attic.

My father has a lung disorder & because there are NO ODORS I am wanting to dispel the notion that his lung problems are related to this. I am DEFINitely also in the process of having the raccoon problem alleviated. THANks - Donna 7/12/12

Reply:

Donna I am skeptical that "air testing" or "air quality testing" is going to provide any definitive data on the presence or absence of an air quality issue due to raccoons whatsoever, nor am I confident that allergens you'd find would be related to raccoons in the attic.

You might test the occupied space, including settled dust, for high levels of insect or animal allergens, including dust mites, animal dander, insect fragments. "Air tests" alone can give results that are "wrong" by several orders of magnitude when looking for particles.

When raccoons invaded our house through an open soffit we found them returning night after night to open a box of shiny Christmas ornaments that they considered great fun to bat around the attic floor. The remedy involved these steps:

1. Wait until the raccoons have left for the day - don't confront a raccoon cornered in your building or you're asking for a fight and maybe a bite
2. Close off their entry opening
3. Clean up the mess and if necessary use a sanitizer.

If you're not up to these steps call a local pest control or animal control professional.

Question: foul smell I think is cat urine: how do I get out of my lease?

I just rented an apartment. I discovered it has a foul nauseating smell. I now suspect the issue is that cat urine has saturated through the carpet into the wood and everywhere.

It is disgusting and I have to move out. My question is how do I prove this to the landlord or a judge?

I need to get out of my lease because I know the landlord will not want to spend monies to truly fix the problem. Thank you! - (Dec 31, 2014) Pat said:

Reply:

You can document the presence of the odor with witness's, black light, and lab tests of a sample of building air.

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Continue reading at ANIMAL or URINE ODOR REMOVAL or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Animal Odor & Allergens Articles

• ANIMAL ALLERGENS / PET DANDER - home
• BLACK STAINS from ANIMALS
• CAT DANDER in BUILDINGS
• OZONE MOLD / ODOR TREATMENT WARNINGS
• PET ALLERGENS / PET DANDER
• PET STAINS & MARKS in BUILDINGS
• URINE / ANIMAL ODORS IN BUILDINGS - home
  • ANIMAL or URINE ODOR SOURCE DETECTION
  • ANIMAL ENTRY POINTS in BUILDINGS
  • ANIMAL NOISES in BUILDINGS
  • ANIMAL STAINS & MARKS in BUILDINGS
  • ANIMAL or URINE ODOR REMOVAL
  • ODOR REMOVING DETERGENTS
  • PET STAINS & MARKS in BUILDINGS
  • URINE ODOR REMOVAL at BUILDING EXTERIOR
  • URINE ODOR REMOVAL in CLOTHING
• UV LIGHT BLACK LIGHT USES

Suggested citation for this web page

URINE ODOR SOURCE DETECTION 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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Citations & References

In addition to any citations in the article above, a full list is available on request.

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