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This article describes common indoor stains caused by animals and pets on floors and walls due to pet urine or simply from a pet frequently lying against or touching a building surface. These photographs also assist in determining when a building has previously housed pets or other animals even if none are currently present. We discuss the cause and cure of various types of pet stains. Readers concerned with pet stains on walls should see Pet Stains on Walls. Also see ANIMAL ODORS IN BUILDINGS for a discussion of the diagnosis and cure of odors due to animals buildings, and see CAT DANDER in BUILDINGS for a discussion of animal allergens indoors and how they are detected and removed.

When investigating a building for a mold problem, you can save mold test costs by learning how to recognize Stuff that is Not Mold or is only Harmless Mold but may be mistaken for more serious contamination - save your money. Save your mold test money, and increase the accuracy of your mold contamination inspection or test for toxic or allergenic mold in buildings: review these items to learn recognize non-fungal materials or even possibly harmless cosmetic "black mold" often mistaken for "toxic fungal growth."

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How to recognize black stains on indoor walls and trim caused by pets, not mold

Dog Stains on Building Drywall

Provided the stains are due to simple contact between an animal and a building surface, the cures for dog or cat dirt marks on building walls or trim are simple cleaning or at most, re-painting.

Pet Urine on Building Walls or Carpets

When a dog, cat, (or in some reported cases humans) has urinated on carpeting we recommend that the carpet and carpet padding be replaced. The flooring or subflooring below the urinated-on carpet needs to be inspected for stains and penetration of urine as well.

Killing or Removing Pet Urine Odors?

There are lots of reasons that animals urinate in buildings, and pet owners know most of them: no access to a litter box, dirty litter box, dog shut indoors too long, dog or cat marking territory, fear, etc. A pet shut into a room and abandoned may have no choice about where it relieves itself (photo, left shows scratch marks from a dog who spent too many hours shut in a room).

Because urine leaves an odor in wood surfaces that is difficult to remove, once an area has been used as a cat or dog toilet, animals are likely to return to that spot to pee on it again. While special pet deodorizers and cleaners are available to clean and remove pet odors, we find that often the animals will continue to return to the scene of their accident or crime.

If the amount of urine was very small, an ounce, one event, covering just a few square inches, it may be possible to clean and seal the subfloor using a lacquer primer/sealer, clear shellac, or another appropriate re-finishing coating.

Readers should see ANIMAL ODORS IN BUILDINGS for detailed advice on how to find and remove pet and other animal or humanb odors and smells in buildings.

Pet Urine Stains on Building Floors

Often when an animal has urinated one or more times on a carpeted floor, later removal of the carpeting will disclose dark stains in the wood flooring of a finished floor.

Our photo (left) shows severe urine staining on a hardwood floor of a bedroom outside of a bath. The owner was unaware of the stains until the carpeting was removed.

The white colors in the stained area demonstrate the futility of attempting to remove the animal stains by bleach.

If stains penetrate only a millimeter of wood it might be possible to sand and re-finish the floor, or to use a combination of sanding, bleaching, and re-staining of the finish floor.

But usually we find that the urine stains have penetrated the wood so deeply that flooring replacement is about the only option if the occupants don't want to live with these stains.

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MOLD APPEARANCE - STUFF THAT IS NOT MOLD
  HARMLESS INDOOR PARTICLES
    Basketball Mold Syndrome - BBMS
    Black stains from soot/thermal tracking
    Black stains from animals
    Black cosmetic mold
    Efflorescence & brown deposits
    Efflorescence & white or brown deposits
    House dust
    Pet Stains on Walls
    Pollen
    Sprayed foam insulation
    White stuff that is not mold
    Wood e sap

• Basketball Mold Syndrome - BBMS why dirt and stains may be mistaken for toxic harmful mold
• Black mold on building surfaces that is harmless cosmetic material, not "toxic black mold" indoors
• Black stains from soot/thermal tracking or marks on building interior walls caused by thermal tracking, this is not mold
• Animal Stains or marks on building interior walls caused by dogs, cats or other animal stains on building carpets, floors, walls, doors, trim: how to diagnose and remove pet stains and odors.
• Black cosmetic mold - such as black stains due to Ceratocystis or Ophistoma fungi that were on framing lumber at the time of construction may be completely harmless, cosmetic only. At Black cosmetic mold we discuss some simple but reliable ways to identify cosmetic molds that have been present since time of building construction. In our companion article, Recognize Harmless Black Mold, we discuss two specific harmless, cosmetic black molds commonly found on framing lumber.
  
• Efflorescence & White Stuff white, tan, crystalline, tan, or other-colored mineral salts on foundations and masonry walls - white fluffy stuff or white crystalline stuff often found on building walls may not be mold at all, though it is an indicator of problem leaks, moisture, dampness. Efflorescence describes white fluffy crystalline material that is not mold. White Mold describes actual white or light colored mold in buildings.
• House dust which may or may not contain mold, allergens, or other problems
• Pollen may contaminate indoor dust
• Sprayed foam insulation- that looks a little like certain fungal growths in crawl spaces or other building areas, usually yellow or white in color
• Wood sap- clear or crystalline tan or yellow droplets found on wood framing, often in attics

More Information on Building Diagnostic Inspections and Repairs

• How to Look For Mold, Hiring a Mold or IAQ Consultant, Getting a Remediation Plan
• Looking for Mold what mold is often found where in buildings - simple technical presentation
• Mold spores in the Home - a Photo ID Library for detection and identification of mold allergens Recognizing
• Allergens: What various indoor allergens look like - identification photos to help identify pollen, dust mites, animal dander, toxic or allergenic mold - Common Mold and other Allergens, Irritants, Remedies & Advice
• Stuff that is not mold but is often mistaken for it - things you may not want to test. Also, not all "black mold" is toxic - here are examples of harmless black mold .
• Animal Allergens: Dog, Cat, and Other Animal Dander - Cleanup & Prevention Information for Asthmatics and regarding Indoor Air Quality.
• Mold in Fiberglass Insulation© 2005 comments about a field study in process, & more about health hazards from fiberglass insulation - DJF
• Mold Investigation Tips for Home Inspectors how to find mold, where to look, what is likely to be important. Advice to building inspectors intending to inspect or test for toxic or problematic mold indoors, mold inspection methods, and mold test methods which are valid or invalid : the house eating fungus or "poria"
• Mold Central: indoor air quality investigation case histories, key links what to do about mold and indoor allergens - our Fear of Mold "Mycophobia" WebLog-Blog.
• Ozone Warnings - Use of Ozone as a "mold" remedy is ineffective and may be dangerous. Rot concerns in buildings-some building mold such as Meruliporia incrassata "Poria" risks serious rot and hidden structural damage
• Basketball Mold Syndrome - BBMS- sudden attention to old clues in buildings makes them seem brand new to some observers
• Frequently Asked Questions About Mold -- check this FAQ list & IAQ Site Map to see if you can find a quick answer to your mold concern

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