Urine Odor out of Concrete

I am continuing with my series on questions from readers with answers.

Rick writes and asks “Can you please tell me more about the odor neutralizer? I am working with concrete that has been used in a dog day care / kennel for a couple of years. So far I have tried a degreaser/cleaner, enzymes (which included covering the floor with plastic for 24 hours to keep it wet), white vinegar, a high-tech odor neutralizer, and finally bleach, both straight and diluted. I have power-washed at the start, and again after each of these treatments. The bad odor has been reduced but it is still present.”


Thanks for asking. Concrete is porous so what you have is a situation where dog urine has been soaking into the porous surface (it sounds like continuously) for a couple years. At least some of the products you have used are working. The enzymes work by digesting the urine residue. The reason you keep them wet its two-fold. One: They have to be wet to be active. When they dry they do nothing. Two: To get them to soak into the concrete far enough to reach the urine, which would be in pretty deep. Bleach uses oxygen to break down the urine. It will work also if it can reach the urine in enough concentration and for a long enough time to work (which for oxygen is fast). Washing is good and it will remove the urine it can get to. You do need to be careful with power washing though because it can drive the urine even deeper into the concrete depending on how you do it. Neutralizer you asked about also has to come in contact with the urine to change the molecules. So your challenge is to get one of these (a good product) deep enough into the concrete. Where the urine is after a couple years of soaking in. One suggestion is to apply a product and keep it wet for several days. The longer it is wet the deeper it will penetrate. Also make sure that the urine smell is not coming from surrounding items. Is there wood close that might be contaminated or fabric or even dirt. Urine will wick up several inches into other materials when present. It is common not to be able to completely remove all the odor in a situation like yours. (concrete or even wood) So an option used by professionals is to seal the concrete. After you have removed the majority of the odor you can then seal the concrete with a good pigmented shellac, varnish or acrylic sealer. These sealers have microscopic holes left in them when they dry. These holes are larger than the odor molecules so odor can still get through the sealer. If you apply two coats of sealer this will help eliminate that issue. The end result is a completely satisfactory odor neutralized environment. Get back to me with any additional questions.

13 thoughts on “Urine Odor out of Concrete”

  1. I have tenants that have allowed their dog to urinate and deficate on a tar and gravel roof to the point that it was covered in dog feces. Other tenants stated this has been happening for 3-4 months every day.
    Can the urine and feces break down the tar roof. If so by what process? One roofer said the roof is contaminated. Another stated that the ammonia and acidity has damaged the roof? Will the urine odor stay in the tar and smell during hot humid days. Both stated that the roof has to be replaced is this true?

  2. Ned
    Let me start by saying I am not an expert on roofs. I am aware though that the tar (and tar materials) are used to seal the roof and protect the building from moisture. The gravel is used to protect the tar from the sun deteriorating it and breaking it down. I don’t believe that if the roof is in otherwise good condition that the urine and feces would damage the ability of the tar to seal out moisture. And it certainly would not harm the gravel so that it could not do its function. Yes the roof would be contaminated. Anything the urine and feces comes in contact with would be contaminated. It can be decontaminated by the use of chemicals without replacing the roof. Several type of chemicals will decontaminate urine. Bio/enzymes are the primary organism used to break down sewage in treatment plants. These chemicals have to come in contact with the urine residue to break it down. You would want to clean the roof as completely as possible fist and then treat with a good chemical that will break down the urine residue and not harm the tar. As these chemicals break down the residue they eliminate the odor. When urine leaves the body it is slightly acid (uric acid) and it immediately begins to change. The Uric acid begins to be broken down into ammonia and carbon dioxide. The ammonia is highly alkaline (ph 11+). As the acidic urine reacts with the ammonia that is being created it forms alkaline salt crystals. When dried urine is re moistened it gives off ammonia gas. The odor of ammonia gas is one part of the distinctive odor that helps us to identify and locate urine. The other component of urine‚Äôs odor is off-gassing from bacteria that grow abundantly in warm, dark places. I do not know exactly how this process would affect the tar materials on the roof. Thank you for the question.

  3. Hi there!
    My husband and I recently bought a house with the contingency the old owners will pay and fix the smell of dog urine from the basement. Apparentley the dog was peeing in a couple of spots for a long time.
    Problem is they did have a professional power washing place come out and do the basment a couple days ago. Well I wentr over there to check it yestereday to see if it was gone and I smelled that pluse the wash smell together. Before I even reached the basement! It was being aired out and I’m not sure if it will be completley gone. It sure does’nt smell like it!
    They do stll have to fix it, is there any chemical or sealer I should reccomend to the current owners!?

  4. Kristen
    Two keys to getting effective results when killing the odor associated with dog urine. One is using a chemical that works and the other is getting the chemical in contact with the urine residue. There are several types of chemicals that are effective in killing this odor. There are good and bad products in each type. Oxidation is one type that works quite well. Clorox bleach is an oxidizing product. It will work well but it has to come in contact with the urine residue for a long enough period of time to do the job. If the dogs have been urinating in the spots you mentioned for months or years then the urine has built up and soaked deep into the concrete. You of course want to make sure each area affected gets cleaned and treated heavily enough to reach the residue and counteract it. I am assuming it is concrete and an unfinished basement. If it is finished with carpet and pad and Sheetrock walls etc. then you have a larger challenge. The principles of odor removal remain the same for the different situations but different materials need to be dealt with individually. The chemical needs to contact the urine. If you are using a enzyme product, it has to come in contact with the residue and stay moist for a long enough period for the enzymes to digest the urine molecules. For concrete I would try Clorox bleach and keep it wet long enough so it can soak deep into the concrete. If necessary use two coats of a pigmented shellac concrete sealer after as much odor as possible has been eliminated.

  5. Great information for these tough situations! Another benefit of shellac is that is safe and non toxic once dry. The solvent used in shellac is ethyl or denatured alcohol that quickly evaporates to form a seal on just about anything.

  6. I can actually put my nose up to the upholstery where he has soiled it and can detect no cat urine smell. I bought the Starter Kit and was amazed that it really does remove the smell of urine.

  7. Thanks! SUN is excellent on neutralizing all organic odors. Especially urine. All types of urine, including cat urine and of course what we specialize in, dog urine. I am glad it worked out for you. If you get SUN to the urine residue (that is in contact with it) it will remove the smell.

  8. ………………………………..Male Dog UrineGwen Crocker – Imperial MO Wednesday July 06 2011 ……………Very happy! …………………………..SUN – male cat urine-GONE!!!!!Esther Mott – Phoenix AZ Monday July 04 2011 ……………This product is unlike any other ever! Im a landlord and constantly have a problem with tenants and their cats which is the WORST kind of urine I tell everyone I know about this stuff!……………………….

  9. In my experience, I have found that direct sunlight, white vinegar and enzyme cleaner to be effective at cutting through the ammonia in urine and rendering it odorless. When all else fails, I will close the concrete with concrete sealer.

  10. Sun light does neutralize some odors just as it does have an effect on dyes. Many times you will see the colors in carpet faded or removed next to a south facing sliding glass door when there is direct sun light on the carpet. Vinegar is acidic and will neutralize some alkalinity in urine. You use white vinegar because it has no coloring added to it that might stain the carpet . Fresh urine is acidic and with time changes to alkaline so putting vinegar on fresh urine is adding acidity to acidity. Which is not recommended. The enzymes in a good enzyme cleaner will digest and break down the molecules in urine rendering it odorless and enzymes also remove some of the staining from urine. It takes time for the enzymes to digest the urine residue so the area needs to be kept damp for a period of time (hours to days). If the enzymes dry out they are no longer active. A sealer will help but the microscopic openings (holes) in sealers are larger than odor molecules. This means even after sealing some odor can still find its way through the sealer. A second coat of sealer helps but make sure you remove as much odor as possible with cleaning and effective odor treatments before sealing.

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