Asked on Mar 1, 2012

What would cause rooms to smell like cat urine, when there are no cats in the house?

GradyMrsmmcsDla2590020
+137

Answered

The crawl space has been checked for plumbing problems and critter invasion and has been cleared, as have the attic spaces. The odor started after the crawl space was encapsulated for mold.
101 answers
  • SawHorse.net
    on Mar 2, 2012

    There could be so many reasons: 1. Since the crawlspace was encapsulated, the ductwork is now in semi conditioned space and may have had critters in them. Since the space is now sealed, any smells are not mixed with the outside air. 2. What did they use to treat for the mold? Perhaps the chemicals were urea based and that is why it smells. 3. When do you notice the smells? Time of day? Time of year? Type of weather? Even thought the crawlspace was sealed, doesn't mean that it is perfect and done correctly. I have fixed spaces that were encapsulated and not that well. When it rained, gases from the soil would get trapped in the house and cause new odors that were not present before. It is also important to have a certain amount of ventilation in the crawlspace. This can be achieved by adding a few 4-6" supply ducts. 4. I have seen the smell come in from the attic during the winter since the insulation was contaminated. It would be worse in the Summer. If you could give us some of the conditions that you are experiencing the smell under, perhaps we could help a little more.

  • Madeline C
    on Mar 2, 2012

    Thanks sawhorse. It seems to be all the time; not related to seasons. Seems to be in the crawl space. Incidentally, how do I get posts in other categories? I would like to have it in a general category. Thanks

  • Can you tell me a bit more about how they encapsulated the crawl space? if they used vinyl liners for the soil, these sometimes give off odors. Also depending upon what chemicals it was that they used can cause strange smells as well. Knowing a bit more about what was done and why can help find the root to the issue.

  • SawHorse.net
    on Mar 3, 2012

    Not sure how to change the category. I used to be able to and now it looks like the function is missing. I just let the host of hometalk know and should have a reply shortly.

  • As supers we were able to reset the category but that feature is not there now. I will send a email to those in the know to see if it can be moved for you.

  • Madeline C
    on Mar 3, 2012

    Thanks! Michelle at hometalk responded to my question as well. I'm still not sure how to do it, but in looking at both your credentials, I think I'm in the right categories, so I'm not going to worry about it.

  • Miriam I
    on Mar 4, 2012

    Hey Madeline. It was I who emailed you yesterday :) Your question is in the correct categories. Thanks Woodbridge and SawHorse for alerting me to this as well. Just as a general FYI, when you post a question you can select the categories you want to put it in. Once the question is posted it will be categorized by the system so don't worry if you didn't categorize correctly, or didn't categorize it at all. Hope this makes sense :)

  • Madeline C
    on Mar 8, 2012

    Thanks for the answers, but I'm still hoping for more ideas.

  • Madeline, can you tell us more about this encapsulation that you had done? did they seal for moisture? what about dealing with insulation. What did they do along that line? Need more info other then just treated or encapsulated the crawl space.

  • Donna James
    on May 26, 2013

    I have the same odor problem in my encapsulated crawlspace. The cause can be the liner used but most likely it is the sealant tape that was used. The adhesives give off an odor that smells just like cat urine. If it is an option for you, you can have the encapsulation redone with less volatile, more expensive materials or, (the option I am considering) having a radon fan installed. The radon fan will create negative pressure on the house by sucking air out the crawl space and venting to the outside. This counteracts the positive pressure where air gets sucked into the house from the crawlspace (bringing the odor with it) -- like when your attic fan spins or when you open windows.

    • Jeff W
      on Jul 12, 2014

      We had our basement encapsulated in the fall and made it through winter no issues. Now since Spring we are smelling this bad smell. It is making me sick I believe. Did you find a solution? We live in GA too. I have tried air cleaner, odor remover etc. with no luck. Basement is dry and at 40 percent humidity so dry. I am hoping the smell eventually dissipates but so far it is strong and we smell it in the living space. A subtle yet bad smell. What to do???

  • Steer clear of the radon fan or any sort of ventilation fan in the sealed crawl or basement area, unless you have radon in the crawl space and if its professionally installed and checked. The fan counteracts the air in the house causing higher energy use and can cause back drafting of appliances if incorrectly sized and located. while the theory sounds good. I have seen many of the so called ventilation units that are supposed to remove humidity cause down drafts in hot water heaters raising CO levels within the home.

  • Becky
    on Dec 6, 2013

    Hi, I had my crawl space encapsulated as well and it smells in my house like cat urine. Has anyone come up with a solution I spent thousands already.

    • @Becky Can you describe the process that was used to seal off your crawl space? Materials, reason, and how? You can always call me to discuss if its a lengthy explanation I will return your call to provide you with answers that may shed a light on the odor.

  • Wanda Coleman
    on Feb 2, 2014

    We've not had anything done to our crawl space. We have an outdoor cat that does not come inside at all but have noticed the smell of cat urine in the last week.

  • Jennifer Emick
    on Feb 2, 2014

    Probably off-gassing from adhesives or plastics they used. Suggest putting a damp rid or other odor absorber in the space (even clay cat littler), and a couple of air cleaning houseplants in the affected rooms.

  • Jeff W
    on Jul 12, 2014

    We had our basement encapsulated in the fall and made it through winter no issues. Now since Spring we are smelling this bad smell. It is making me sick I believe. Did you find a solution? We live in GA too. I have tried air cleaner, odor remover etc. with no luck. Basement is dry and at 40 percent humidity so dry. I am hoping the smell eventually dissipates but so far it is strong and we smell it in the living space. A subtle yet bad smell. What to do??? I spent a lot on the encap. Didn't anticipate this bad chemical-cat urine-odd smell.

  • Everyone is talking about having their basements and crawl spaces encapsulated. What I need to know with those who are having issues is how was this done? Are you talking about the walls being sealed? or the floor and walls? If so how and what kind of materials were used? Many times the plastics that contractors use will outgas causing all sorts of foul odors. If the plastic gets warm for what ever reason it gets worse. More info on the process of your encapsulation please.

    • Jeff W
      on Jul 13, 2014

      Our basement crawl had the small vents sealed with a fiberboard type material. Then there was 12 mil (I think) white plastic put on the walls and the floor. The provider seals these to the walls with some adhesive. Then the seams were sealed with a tape like material. We had ours fogged with a mold retardant afterwards. This was all done on ATL in he fall. There was always an unusal smell afterwards but I figured it was just going to stay in the crawlspace and would dissipate. So no really bad odor emerged until this Spring when it got warm then hot and we were runnuing our AC which is a horizontal unit in the crawlspace. Seems like that odor worsened (kind of a cross between cat pee and an earthy smell and chemical smell). Now our living area smells a bit like it. I talked to the installer and he said he had one complaint in the past on the plastic he had used about odor but he stopped using that brand. He suggested we get a fan and vent air out. Or fog with a deodorizer. I am open to any and all ideas. I cannot wait till Fall when I can open windows! Help!

  • That's the plastic liner they used. I had plastic runners placed in one of my past offices a few years back. Then after a short while the office began to stink with what I would describe now as a cat odor. I removed the runners and the smell went away. I would install a small vent fan on one of the past wall vents. They make ventilation fans that fit exactly in the same size hole in the cement as the screen vent is. But, the real issue is you paid him to encapsulate the crawl space. This is to prevent moisture from entering into the house and crawl area. He is responsible for removal of he odor after all its his product that is causing your issue. Also get the return ducts properly sealed. If there is air leakage in the crawl space area any leaks on that duct will cause the odor to be drawn into the house as it currently is. I also have a concern if its also a furnace. If the room is tight then where is the air for combustion? If you do not have fresh air entering into the furnace you will possibly have created a CO poisoning issue. But the bottom line is the vinyl he used is causing the smells your getting.

    • Jeff W
      on Jul 13, 2014

      Thank you for the reply. I also have a gas water heater in the crawl but I have a 6 inch flexi-hose bringing in air from the outside. I have CO monitors down there as well so hopefully I am protected. One question on the out-gassing....does it eventually go away by itself with time? If the living space did not have this smell coming in from the furnace I would not be as concerned but that is the real issue. I will have my return ducts looked at so thanks for that suggestion. J

  • Jeff with most outgassing issues, yes it does go away. Think of it as a new car smell as the plastics stop giving off odors the car smell goes away. The only issue is if you can stand the odor long enough and with it coming from the crawl the trigger that causes the outgassing may be heat or something along that line and it may continue for years. You need to check to see if the crawl space is under a negative pressure. This would be done using equipment used to measure draft. You need to determine if the crawl is in a lower pressure then the house and higher then the outside. If when the heater runs a vacuum of sorts can be created even with the hose of fresh air entering. That can cause all sorts of issues. Do not trust the CO monitor all that much, its settings are so high so not to have false positives on a daily basis you can be having issues even if do not detect it. IF you really wanted to determine the exact cause of the odor, you can contact EMLab P&K https://www.emlab.com/app/main/Welcome.po and ask them about having a SUMA can test done at your home. This test involved using a stainless steel can that is about the size of a small soda bottle. Its evacuated and put under a negative pressure. You get it and a special device that allows the air to be drawn into it over a period of several hours. Once the air fills the canister you remove the device from it and mail it all back to the lab. They then analyze the contents of the air and one of their people will tell you what is in the air that can be causing the odors. Armed with that information, you can make the correct decision on how to fix. So if the company that installed the vinyl liner into the crawl gets the word that its the outgassing of the chemicals in the seal, they can not argue its not them and they will need to find a way to fix the issue for you. Costs of these devices run around $125 with lab fees. So its not to expensive and you may get some valuable information.

  • Carol
    on Jul 19, 2014

    Get a cheap spray bottle from the Dollar Store, fill it with Club Soda and mist the entire area. That also works for spills to keep it from staining. Works better than baking soda which is dry.

    • Jeff W
      on Jul 19, 2014

      Carol - thank you. So are you saying that club soda will neutralize the vapor barrier outgassing smell? I am willing to try anything but this is not something I would have thought of. Jeff

  • Carol
    on Jul 19, 2014

    I find that club soda neutralizes odors better than baking soda on most anything you can get wet. I have used it for years. White vinegar works best on smoke smells. I don't like to use vinegar on urine smells as the acidity combined with the acidity in the urine tends to make a stronger more stringent odor until it neutralizes. Why make it worse before it gets better?

  • AFS
    on Jul 22, 2014

    I have been installing encapsulation system's for about five years. I'm not sure if anyone has found out exactly what causes the cat urine odor. That being said I think there a couple different factors that can contribute to an odor issue after encapsulation. Do you know if the installers removed all organic materials and the old vapor barrier before laying in the liner? If these materials are just covered over, as they degrade they could give off an odor. They're have been a few homes where the install was done perfectly, but down the road there became an odor issue. We solved this issue by installing mitigated pipe under the liner which connects to a radon fan and is then exhausted to the outside of the home.

  • Odors from encapsulation systems are caused by the vinyl itself. Not from any organic material located below the liner. Like any plastic or vinyl the quality depends upon the product and where you purchase it. In the case of where you have installed the ventilation system below the liner. You have in effect installed a radon mitigation system. And doing so if your not licensed you can be fined quite heavily. Be sure that the fan vent is located above the roof eave and not below. This is exactly how radon systems are installed where basements, or crawl spaces have no cement cap over the soil.

  • AFS
    on Jul 22, 2014

    Alabama does not require for an individual or company to be licensed to do a radon mitigation system. When we install this system we are simply trying to remove an odor, not radon, which would not require us to install the system to meet code for a radon system. In the few homes that we have had an odor problem, installing a ventilation system has always worked to resolve the issue, whether it be from organic material in the crawlspace or from the vinyl liner it's self.

    • @AFS Thanks for the useful information. Personally I would be sure to install any system to meet the standards required for radon mitigation work. Not doing so I would think would open you up to liability issues should someone get sick from the discharge. Interesting none the less!

  • Jeff W
    on Jul 23, 2014

    Please tell me how the radon fan works. Is there piping that goes underneath the vapor barrier and if so how long is it and how far does it go? Does the encapsulation have to be removed or just cut? How do you know the odor assuming it is from the vapor barrier is coming from underneath the barrier versus from the top? Wouldn't a ventaliation fan work as well venting out of the vents the home already has ( note they are covered today with fiberboard and vapor barrier). I'm thinking I need to get something done as the smell is potent and not diminishing. I did put a floor fan at the entrance outside entrance door to my crawl as a temporary set up. It may be helping slightly as the smell in the house is less noticeable. But it s still pretty strong. What does a radon fan cost to install roughly? Thank you guys are extremely helpful. I cannot seem to find anyone in Atlanta who knows what I am talking about. The encap installer is coming tomorrow to inspect the smell but he is denying the smell is from his work as he never has had a complaint, J

  • @Jeff W The radon system and fan is really a very simple system. Radon being lighter then air flows from higher pressure zones to those with lower pressures. A house much like a chimney draws up air from the basement which flows upwards out of the house from the attic. (this is what home energy saving systems are all about) This air as it rises lowers the pressure within the basement or enclosed crawl space very slightly. This pressure can be measured using special tools. With radon being lighter then air, the slightly lower pressure within those areas draws the radon out from the soils, and cracks in the cement that is on the floor. What a radon fan simply does is lowers the pressure ever so slightly more then the pressure in the basement or crawl space. In basements on existing homes, there is gravel (hopefully) below the cement. This gravel allows air to flow ever so slightly though it. The tech that installs these systems checks the flow using a few small holes and a vacuum connected to one. They drill small holes on each corner of the basement and while the vacuum is drawing air out of the hole its attached to the tech blows some smoke over the other holes to see if its drawn into them. If so it is known as good communication under the slab. Once that is established the contractor opens up the hole where the vacuum was located large enough to place a 4 inch pipe into it. They reach into the hole and open it so it looks like a small bell shape. Once that has been done, the pipe is set into the hole so its just below the surface of the cement slab. Then its fastened into place using cement. Once this is done a pipe is connected to several others and either goes outside or up into the attic. In these locations, attic or outside the fan is installed. Its a in line fan about 1/4 hp made of plastic. Uses very little energy and is very quite. On the other side of the fan the plastic continues until it exits over the roof eave or out of the roof in the attic install. The fan must never push the air through the house, it must always draw the air until its above the ceiling of the top floor or outside. The reason is if the fan pipes come apart, the radon levels that can be emitted even if low to start with as found in testing, can reach severe levels and can be very unhealthy to those breathing it. IN the case of the crawl space as AFS has been referring to, there is nothing to connect the fan into. While a cement slab acts as a air barrier of sorts, if the fan was placed with a inlet pipe above the crawl space floor, it would be nothing more then a ventilation fan. What he is doing, is installing a plastic cover over the entire floor, then using perforated pipes I assume and he can correct me if I am wrong, these pipes are placed around the edges or down the center of the crawl and sealed over using the vinyl liner or plastic. Thus creating that lower pressure plane where any odors in his case, or in the case of radon from entering into the living area of the home. Any outgassing or radon that comes up from the soils is then captured by the lower pressure of the fan system and drawn out harmlessly to the outside of the home. The fan itself is really not all that strong. It creates very little suction. Its only job is to create a lower pressure then what the space above it has due to stack affect of the home. Hope this helps!

    • Jeff W
      on Jul 24, 2014

      Sir from Woodbridge - would you mind sending me your number as I have a few more Qs for you and easier to talk through. My email is jeffweikert@yahoo.com thanks so much

  • Tyrenta
    on Jul 24, 2014

    jumping in here with a very similiar issue, any additional comments would be appreciated -- I purchased a home last year that had an attached crawl encapsulated the year before (march 2012); both the crawl has a dirt floor, and the main basement is fieldstone with a crumbling floor; we didn't notice anything during inspection in the spring, but when we moved in over the summer the smell was overpowering, and rendered the central AC unusable as it would come out the vents -- a horrible musty cat urine smell. The humiditity in the crawl was in the high 80s at the time, and then over the winter as it fell the smell abated though you could still detect it very very mildly if I were to put my head in the crawl. This summer it has returned; I have a dehumidifier in the basement that keeps the humidity ~55% in the main full size basement, though the attached crawl was still elevated ~75% until very recently when I vented the exhaust into the crawl; it has since dropped to 55-60% humidity, but the odor remains. I'm not sure of the encapsulation materials used, but I am very curious about how certain you are Woodbridge that the odor is caused by the actual ecapsulation and could not be a mold issue. The only other info I have is that there are mice making a home down there that I have not yet fully eliminated as I randomly catch one every few weeks, and at one point I understand there may have been some rats making a nest in the crawl (!); the original insulation was removed when the encapsulation was done. I don't have any more info on WHY the encapsulation was done, other than the selling broker seems to have required it as it was listed the day after the work was completed. Would this SUMA test be the best approach? I don't see it listed on the site you linked to, though they do have an office in my town.

  • The first thing I would do is to get a black light and put it into the crawl and look around. Urine will glow a bright green. If that is the case chemicals such as Natures Miracle will remove the odor. There is a lot of concerns here. If the crawl space was properly encapsulated, humidity levels should be much less then what your achieving. The really whole reason for the encapsulation is to lower humidity levels. While the added bonus makes it useable for storage its really only about moisture control. With that said, I am wondering if at all the crawl was properly encapsulated at all. A properly done crawl would include the entire floor and up on the walls just shy the top place. A small amount of wall needs to be exposed for termite evaluations. All seams on the vinyl should be sealed using an adhesive. Although some use tape, this will fail in short order. Ideally done, the inside of the crawl should be able to hold water much like that in a pool. Properly prepped the installer should have removed any odorous and organic materials. Raked the floor level and removed any sharp objects that could cause punctures in the vinyl material. Also note I am talking vinyl here. Plastic which is what most folks use, simply does not last all that long. Even the slightest amount of natural light that gets into the crawl space will degrade the plastic over time causing it to crack and decay. Any insulation that is on the ceiling of the crawl space should be removed if indeed there is a heating or cooling system inside the space. Insulation should be provided on the walls and up into the top plate area. Ideally this should be foam boards and foam. Fiberglass can smell fishy sometimes. The cooling/heating duct system also needs to be addressed. If the crawl space is accessible to the basement assuming you have one. or accessible through a floor hatch. You need to do a quick experiment. Turn on the blower switch to fan on. Then enter into the basement or in the crawl if that is all you have. Close the hatch or door for about 1 min. Then ever so slightly open the door/hatch with your face near the opening. Is there a breeze that hits you? You may even feel some pressure to open the door or the door will tend to close on its own if it enters out of the basement. If that is the case, this is a sign that your duct system is incorrectly sized and that its starving for return air. This condition will cause all odors from the basement/crawl space to enter freely into the duct system. In addition, this can cause back drafting of the flue pipes for the combustible equipment in the basement. Causing flue gasses to enter into the house. Duct sealing is a must if that occurs along with a HVAC tech adding additional return duct to the living side of the house. Although you want to seal the supply ducts as well, they will not cause odors to enter as they are under positive pressure and will not draw odors into the home. You said that the basement was sealed prior to sale of the home? The listing agent may have first hand knowledge that there was a prior issue with the area and used encapsulation as a cover up of a larger issue. This is fraud if you can prove that the encapsulation was done to cover over a pre-existing condition. Discovery laws prohibit knowingly covering an issue without disclosing it. Not sure how long you were in the house sense this was done and you purchased it. But I would be looking a bit harder as something does not sound quite right. I was going to say something smells, but you get the idea.

  • Jeff W
    on Jul 27, 2014

    I did find out that my crawlspace was encapped with 12 mil Reinforced White / Black vapor barrier by Americover. When you read the description on their web site it sounds like a great product and made for this purpose. I am inquiring about this product outgassing - my smell also started with the heat and humidity season here in ATL. I just put in a small vent fan and opened one of the house foundation vents on the other side of the crawl to see if we can get any air movement and move the smell on out. I know that will bring in some moisture but short of pulling up the barrier I am unsure what else to do. I still get the odor in my supply vents in my living quarters when the AC is on. It is a little better but not perfect. I have no varmints or even bugs in my crawl so no issues there. My humidity level with the vent partially opened and dehu on thermostat is staying around 55% right now. It was as low as 35-45% before but I felt like that may have been overkill. Such a frustrating problem....and not much local (ATL) expertise I have found. Standard HVAC guys don't seem to know much about this issue. My encap guy smelled the odor but has not had any complaints but he also thought it might be the vapor barrier.....I can only hope it gets better in the fall and winter and dissipates next Spring/Summer.

    • David G
      on Oct 16, 2014

      @Jeff W We are your neighbor and had the crawl done earlier this year too. Our house also smells like cat urine. It's embarrassing to have people over and I can't stand the smell. Can we connect and talk about a solution please. David G

  • So it looks as though its the chemicals that are possibly reacting to the vinyl. No response from anyone I sent this to. I think they are stumped as I. But glad its not the vinyl. The chemicals alone should not be the issue. You will need to ventilate the crawl well and use a soapy solution to clean it up If you have the manufactures info on the chemicals. I would contact them. They may have an answer to how to clean things up. They may even want to know about this reaction or already know about it.

  • Les Chaffin
    on Aug 24, 2014

    I have a question similar to these. We encapsulated our crawlspace and had the cat oder smell occur after about 4 months. Had the company back out and they said it was likely the material they used. They applied another layer of a newer material over this. It did not help. I installed a vent system similarly used for radon and this worked for over 2 years, then this month the oder is back with strongly. I check the vent fan and all seems to be working fine. I wrote the company and they had not heard of the odor ever coming back. I am not sure what to do at this point. SHould I get another encapsulation company out? just remove the vinyl from the crawlspace. Cant stand the oder. Any suggestions for solution greatly appreciated.

  • Les Chaffin
    on Aug 24, 2014

    I have a question similar to these. We encapsulated our crawlspace and had the cat oder smell occur after about 4 months. Had the company back out and they said it was likely the material they used. They applied another layer of a newer material over this. It did not help. I installed a vent system similarly used for radon and this worked for over 2 years, then this month the oder is back with strongly. I check the vent fan and all seems to be working fine. I wrote the company and they had not heard of the odor ever coming back. I am not sure what to do at this point. SHould I get another encapsulation company out? just remove the vinyl from the crawlspace. Cant stand the oder. Any suggestions for solution greatly appreciated.

  • Tear everything out and start again. Before you replace any product, use a black light to see if there is any urine in the soils. There may be rodents under the plastic causing issues. Plastics can break down. If there is natural light getting into crawl space it will break down the vinyl used in the fabrication of the covering. If the fan system is not keeping the odor out, it could be something else. IS there heating or cooling system located in that area? Do you have cats?

  • Les Chaffin
    on Aug 25, 2014

    thanks much

  • Les Chaffin
    on Aug 26, 2014

    I had another company out to give me an estimate on redoing encapsulation. In his inspection he said he noticed a couple of wet spots on the plastic, pulled the insulation down above and found evidence of rodents. We recommended pulling all the insulation out of the floor joist as a first step before starting over. He said they always remove insulation on encapsulated crawl spaces. Is this true, should I not have/need insulation in a encapsulated crawl space? could this rodent issue have been the problem all along?

  • Depending on how they are doing the encapsulation will depend if insulation is required. here is a photo of one we just did a few weeks back. Odors of urine were throughout the basement and crawl space area. No reason at all to have insulation on ceiling as the crawl space was open to the conditioned basement. If you look carefully all the black dots on the package of ceiling tile laying on the floor is mice droppings. We removed over a half dozen dead mice some that still had maggots feeding on them. Once removed, we cleaned and sanitized the area, fogged it .Next day could not even tell they had a issue.

    q what would cause rooms to smell like cat urine when there are no cats in the house, cleaning tips
  • Tyrenta
    on Aug 28, 2014

    Thnk woodbridge -- are they interchangeable, or are they each for different purposes?

  • Either one will work. The Microban X is my go to chemical. You must understand if you purchase this product, that you use it with care. Its EPA Registered and only allowed to be used by professionals. They will sell it to you however. I also use Ozone machine in some cases. This will kill the odor quickly. But everything needs to be sealed and you cannot enter into area while being treated.

    • Jeff W
      on Oct 16, 2014

      I wish you were in Georgia! You do seem to have a solution. No one here does from what I can tell. And the rodent thing....we once had moles in the basement many years ago....I guess possible they are under the plastic. Causing smell....If mice or rats though I would think if I set a few traps I would catch one then know. If it is rodents - I assume we would have to get rid of them first but would we need to tear up encap or just treat with the Microban? I thought about ozone but seems like many possible side effects - scared me.

  • Darlene Ranaudo
    on Oct 20, 2014

    we have the same issue with our new home that has an encapsulated sealed crawl space. The interior of the home, mostly kitchen area has had a bad smell, similar to cat urine and we don't have any animals. We also have an island with a sink in the kitchen and do not use the sink often so thought it was dry but that does not seem to be the case as I went into the crawl space and it smells like the island cabinet does. I also noticed tons of spider webs and eggs in the sealed crawl and thought we were not supposed to get any. What could be the cause of the horrible smell as very concerned.

  • Paul Adams
    on Oct 20, 2014

    We are having the same problem. The company that encapsulated our crawl space was just here and had no idea what was causing it, since we have no cats. He just said it smelled like cat urine. I a wondering if an ozone machine would fix it permane tly or just temporary.

  • Camille Radich
    on Oct 24, 2014

    We had our crawl space encapsulate to have a cleaner, better insulated space. Seemed like a good idea since we were remodeling our basement. The crawl space was dry, no mold. 5 months after the encapsulation we now has a strong CAT URINE SMELL. We never had a oder problem in the space. I am really regretting the choice to encapsulate the space, we have now created a problem that did not exist. We had the installers out and there solution was to install a dehumidifier. But from what I have read from other people who have experienced this same problem, adding in a dehumidifier does not solve the problem, just another expense. I hope that someone discovers what the cause of the smell is. I am considering having it torn out, going back to what we had. Any info would be greatly appreciated.

  • Jeff W
    on Oct 24, 2014

    Camille I replied already I believe but if you don't see it please let me know. We and many others have similar problem. We still seek a solution and exact cause. Jeff

  • John C
    on Nov 3, 2014

    I live in Nashville, TN and I have been dealing with this issue since 2008! I had my crawl space encapsulated and about 4 months or so later the cat urine smell appeared. I have had the company out several times since and they have had several theories ranging from actual cats peeing on my foundation, rats, to the types of shrubs and trees near my house. Absolute garbage. I would not believe any of the companies trying to give you these excuses. One of the yearly maintenance guys that came out said they had several customers complaining of the same issue. I have tried everything over the years, and I believe it to be coming from the sealant they use or from the vinyl product itself. I currently have a humidifier running constantly and also installed a vent fan in one of the foundation vents. It gets the smell out, but as soon as you turn it off the smell returns. Its a real pain. I feel like the companies installing this product need to own up and fix the problem!!

    • @John C There is another post with the same issue here on HT. The answer can be found easily. Its not always the plastic that is causing the odor, although a good part of the time it is. All depends upon the quality of the plastic used to do the job. Has nothing to do with the sealants. It can also be from the chemical make up of the soils under the plastic. In the past the moisture in the crawl came up and evaporated and vented out of the leaks in the crawl space the outside. Once you sealed the floor, the moisture build up under the plastic has had a reaction to the soil types and causes many of the smells people get. The fix is the fan. But not above the plastic but under it. A Radon type system needs to be installed. Perforated plastic tubing needs to be run around the outside edge and under the plastic. Where its then run outside with a fan that discharges above the roof eves. Must do that because it will extract radon out of the ground. Even if you think you do not have it or never had it when tested. This can change if its present. In any case, most of the time this odor does not happen, and the guys doing the work may not ever even understood why this occurs. Check out this web site and click on the video where it says stinky crawl space. It will explain in a bit more detail of what I just talked about. http://crawlspacerepair.com/

  • John C
    on Nov 3, 2014

    Thanks for your reply and I just checked out the site you mentioned. It seems very logical, but I have seen on other blogs that homeowners have installed these systems and the smell goes away for a while but returns somehow. I am very skeptical of everything at this point for good reason. I will however look into this option in more detail. Do you have any recommended installers in my area?

    • Kristen Robinson
      on Nov 19, 2014

      @John C Hi John, Thanks for your response. We went to the house on Sunday. It was a constant rain all day, but no torrential downpour. The sump pump kicked on while we were there. In addition, we found mold. Definitely a deal breaker...we pulled out of the deal on Monday. It is a beautiful home...completely heartbroken!

  • No I have no contacts near you. The changes in the odors are often the result of different levels of moisture content within the soils. Also some odors are caused by the plastics themselves so the result of changing can be anything from different temps summer/winter how tight your house is energy wise, location of heating system ducts. All sorts of things. But the soil outgassing is the most common cause. Contact the company that has the web site link, they may have installers in your area. Or simply provide this information to the guys that have been out there in the past. If they are doing the right thing, they should be able to follow directions and fix this once and for all.

  • John C
    on Nov 3, 2014

    Thinking back to when I first had this problem, I was told by the company that did the encapsulation that the vinyl liner acts as a radon barrier and is totally sealed. If that is the case, why would I be able to smell VOC off gassing from the soil below?

  • The vapor barrier still allows odors to run through while stopping liquids from flowing. Although slowing the process down it still occurs. The molecular structure allows the fumes to travel through while stopping the liquid. An example is a balloon. You blow it up, but in a few days its flat. No holes? But the air simply migrates through the material. Same with the vinyl materials. Another example is house wrap. Allows for air to travel, but stops moisture. But odors still seep into the space above. Do not let anyone tell you that the vinyl acts as a radon barrier. Unless the pressure is lower below the plastic or vinyl the gas will still come through. In a normal install, air pressure is greater the higher you move through a house. This is called Stack effect. This is the reason why we seal attics first when saving energy. Insulation alone will not do this. The closer you get to the basement or crawl space the lower the pressure in relationship to the outside the space becomes. This pressure may be very slight, only about 2Pa or the same pressure as drawing water up a straw about half inch. Not a lot, but over the entire surface area of a floor this can add up enough to pull the outgassing through the plastic surface. Lower grade vinyl material is even more leaky then higher grade products. If you look at the web site not only do they use a better quality vinyl they use a silver coating to even seal even more.

  • Here is the answer to the issue. Click on smells video. http://crawlspacerepair.com/

  • Grady
    on Dec 2, 2014

    Chrystal meth I have heard smells like cat piss.

  • Gary L
    on Dec 13, 2014

    I guess I need to jump on this bandwagon. Like John C, I am in the Nashville area and we had our encapsulation done by the same people. My encapsulation was done in May 2012 and I still have odor issues. The system has a dehumidifier installed and the humidity is well controlled. There are no HVAC services other than the ductwork in the crawlspace....the units are outside. As the house was not encapsulated when new, the insulation between the crawlspace and the house is still in place. I have gone several rounds with them over a couple years to get the smell issue resolved to no avail. They either don't know the cause or they don't want to address it. In my latest go-round with them, they indicated they wanted to extend the encapsulation all the way to the base plate (making termite inspection impossible). They also want to install a vent to the crawlspace. They also want to charge me $1000 to remove the insulation. They say the odor must be coming from the insulation getting wet although have not indicated how they think the insulation is getting wet. I've taken some of the insulation, wetted it and put it in a plastic bag....nothing. Here we are mid-December and the smell is still strong. I don't know what to do next. Would the SUMA can test mentioned indicate a source for the odor?

    • John C
      on Dec 14, 2014

      Hey Gary, very familiar story. They also told me to remove all insulation in the ceiling of the crawl because they were convinced it was some chemical used in the insulation that was off gassing and wet. I removed it all. No change. After my last post on here I wrote the company a long email asking more questions, they did not respond! I haven't had time to deal with it any more because of work and the holidays. Maybe we should team up on this thing. I honestly feel like there is no way a pro installation company that has been in business this long can't know what the real problem is, they just don't want to eat the cost to fix it.

  • Paul Adams
    on Dec 14, 2014

    Same problem here. Wondering if we had pipes put under the plastic and than vented outside would help. Thinking of opening the vents under the house. At first the company we used where really trying to help. Now it seems they are avoiding us. They say they have never had this problem before. Someone said it was the soil under the house, Our termite inspector said it was the plastic. Don't know what to do and am wondering whose problem it is to fix this. We just had this done in August.

  • InMass
    on Dec 16, 2014

    I'm in the process of researching this cat urine smell coming from an encapsulation crawl space. I have yet to find one of these issues resolved where the urine smell is removed forever. Is there anyone that has a success story?

  • Paul Adams
    on Dec 17, 2014

    I hope so. I am going to call someone local this morning and see if they can help us. If so I will Post.

  • Grady
    on Dec 18, 2014

    It could be junipers or boxwoods, or even stinky damp workout clothes. Did someone leave a gym bag around?

  • Paul Adams
    on Dec 19, 2014

    @Grady--No junipers or boxwoods or gym bag, and certainly no damp workout clothes in the crawl space of my house!!! Or in my house or outside of it!!!

  • Paul Adams
    on Dec 19, 2014

    Had another company here. He said our plastic was not sealed completely to the walls and leak could get through(sounds logical), and that the duck work had leaks in it and needed to be resealed, and that should take care of it. I asked him what they would do if the smell was still there after they did that work, what he would do. He did not have an answer. I want a definite fix for $1700.00 more dollars. I don't know what to do!!!

    • Jeff W
      on Dec 20, 2014

      Paul Same issue. Same scenario. No solution found yet. They cannot deal all books and crannies imo so I don't see that fixing it. I have same issue. My duct work has been cleaned and sealed but we still smell the odorin the house so that is not fool proof either. I think all that sealin will help but not remedy 100%. I'm probably gonna go back to opening a few vents and running some air thru as I have no other options.

  • Mary Take Massieon
    on Dec 20, 2014

    Rodents??

  • Paul Adams
    on Dec 20, 2014

    NO rodents in the crawl space. It has been enclosed with a plastic and there is no way for them to get in. The craw space is about 31/2 ft. high and we have been all under there to check. The company that did the work has put a charcoal filter under there. When it is running the smell is less, however our electric bill was 25 dollars more. They are coming back after the new year to reseal some of the plastic. I am like Jeff and think we might need to open a few vents.

  • John C
    on Dec 20, 2014

    As in my post above, I am going to look back into all this after the holidays. My fix has been to uncover one of the vents that was sealed, open it, and I installed a crawl space vent fan that runs 24/7. It sucks all the odor out and puts it outside. As long as it's running it works, but I am not thrilled about a fan running constantly wasting energy.

  • Jeff W
    on Dec 20, 2014

    We all have the same exact problem after encapsulating our crawlspaces. I have lived here for 30 years and before it was open vents at foundation and a cheap loose plastic. Now that we have spent thousands on the heavy vinyl and the dehu the odor makes it like we are going backwards. My neighbor (not real close but a few blocks away) tried a radon fan to no avail. I have tried every deodoarizer I can find, with baking soda boxes- you name it to no avail. ONLY thing that has worked at all is opening up a vent and letting 2 fans run -one mid way thru the crawl and the other a vent fan (cheap one). It does help the odor in the house. Crawl still has it but venting helped. I am going to get a better vent fan and go agead and do this permanently. I think the smell is there for good/... something about the soil gasses being trapped. No way to tap them 100% - but they need ventilated. I guess before the plastic on the crawl was loose enough and air was prevalent so no odor - ever. This is a case of taking one step forward then 2 steps back. No one I have had at my house has had a clue what this really is - but a smart guy in Carolina told me it was soild gas and I believe it is.

  • Paul Adams
    on Dec 21, 2014

    there should be an answer some where.

  • InMass
    on Dec 22, 2014

    I was about to make an offer on a house with this cat urine smell issue. It was an intense smell. After a month of researching on the web and talking to encap companies, there is no final solution. In the beginning the encap companies first said they have never had this issue. Then they stated the same solutions above; Charcoal Air Filter and Power Venting with no guarantee. There should be a soil sample kit that could test the soil before encapsulation. I think this is more common and people either don't smell it or choose to live with it. In my case the current owner was sold the wrong solution 2 years back for $10k and can't sell the house now. During our home search we have found 2 houses with encapsulation and both had the cat urine smell. Now encapsulation is on our list of home features to avoid.

    • Jeff W
      on Dec 23, 2014

      Not sure but you could buy the house and rip out the encap.....I would hope the smell would then go away. Geez I hope so.

  • Paul Adams
    on Dec 23, 2014

    If you rip out the encap(plastic) will the mold come back? I think I would rather have mold than this smell!!

  • ChrisMax
    on Dec 28, 2014

    I have the same problem and have found a solution on the web. Going to call them on Monday to get the particulars. This is the link: http://crawlspacerepair.com/blog/crawl-space-soil-gas/

    • Gary L
      on Dec 29, 2014

      People who have done this say it works for awhile, but the odor comes back. My opinion is that it would take an extensive network of PVC. More than is practical to do after the encapsulation is already done. If you go ahead with it, please let us know how it works out.

  • Paul Adams
    on Dec 29, 2014

    If you put the PVC pipes with holes in it under the plastic, vented outside with a fan, will it not suck the plastic into the PVC pipes. It seems like air needs to come from somewhere. @ChrisMax PLease ,if you find a solution that works, let us know.

  • Grady
    on Jan 9, 2015

    Are you sure it isn't dog pee? Do you have dogs?

  • Paul Adams
    on Jan 31, 2015

    We still have not found a solution! I would like to open the vents and let some fresh air in--however will that make or allow the mold to come back??I would think someone out there would be able to find an answer, since this is happening to a lot of people.

  • Paul Adams
    on Jan 31, 2015

    Grady , We do have dogs, however they cannot get anywhere near the crawl space. We have a porch and deck all around and lattice with with screen under the porch and deck to keep everything out.

  • Mary Piotrowski
    on Jan 31, 2015

    Pretty sure you are dealing with cat urine. It could have occurred years ago. It does not go away without removing the area cat sprayed. One person I know had to rip all the new linoleum and wood floorbase to get smell out.

  • Sub soils tend to cause odors when encapsulated. Here is a great web site to check out. http://crawlspacerepair.com/once there click on stinky crawl space video. The mitigation system they are talking about is designed much like a radon system. They call it a soil gas mitigation system because if they called it a radon mitigation system, they would be required by the EPA to be licensed as a mitigation contractor which is expensive to do and to get a license for. To answer the question about the fan drawing the plastic up into the pipes etc. This is not the case. These fans draw very little air. Not much more than what you would see with your stove vent on low. The idea is to lower the air pressure below the plastic encapsulation to a point that is just below the pressure that is found above the plastic itself. While house stack effect will increase the amount of air that is required to accomplish this it is still not very much. About 15 Pascal's. Which is about the same amount of suction required to draw up a liquid in a straw about half way. Not very much.

  • Grady
    on Feb 18, 2015

    I have a similar problem at my house. My dogs constantly smell like cat pee, and my cats constantly smell like dog pee.

  • Jeff
    on Feb 19, 2015

    No cat urine. No dogs. Been in house 27 years. Never smelled at all before. Post encap it smells in crawl. Out of desperation re opened vents. Installed 2 fans. That seems to be generally keeping smell out of house But crawl still has cat urine odor. No rodents there. It's not plastic liner. May be the soil and cast iron reacting together under liner. One theory. No real resolution. Unsure about the soil gas mitigation. If anyone actually tries this and it works would love to know Others have tried radon fan with mixed success.

    • Jeff
      on Feb 20, 2015

      One thing I have also learned of encapsulation no one seems to tell you about.....you will see a lot lower humidity as well in your living space....if you have hard wood floors they will shrink and develop cracks. I am assuming since the crawl is so much drier the rest of house is too. I am not sure my furnace humidifier is working very well either so nothing to put back moisture into the air in the living space. Check your humidity levels carefully!

  • Paul Adams
    on Feb 19, 2015

    IF THE VENTS ARE REOPENED,WILL THE MOLD COME BACK? WE ARE DESPARATE ALSO. LOOKS LIKE SOMEONE WOULD HAVE AN ANSWER SINCE THIS SEEMSS TO HAPPEN ALOT. HAVE HAD 2 COMPANY'S COME OUT AND THEY SAID THEY HAVE NEVER HEARD OF THIS BEFORE. WHICH IS HARD TO BELIEVE. WANTED TO REDO THE PLASTIC. I DON'T THINK THAT IS TE ANSWER.

  • Grady
    on Feb 19, 2015

    Jeff, rodent urine smells way different than cat urine.

  • Grady
    on Feb 19, 2015

    Fleece slippers can smell of cat pee if not washed often enough.

  • Grady
    on Feb 19, 2015

    Also, junipers, boxwoods, and irises all smell of cat urine.

  • Grady
    on Feb 19, 2015

    Wet soccer cleats also produce this smell

  • Grady
    on Feb 19, 2015

    Freon from a freezer unit smells cat urineish to some. Also basil wreaks of cat urine.

  • Grady
    on Feb 19, 2015

    Try using a CritterZone air purifier, that should take care of the problem.

  • Grady
    on Feb 19, 2015

    Certain types of lavender smell similar to cat urine.

  • Grady
    on Feb 19, 2015

    Even wet carpet can wreak of cat urine.

  • Grady
    on Feb 19, 2015

    A pile of towels that have sat damp for too long can produce this smell.

  • Grady
    on Feb 20, 2015

    Both of you should use a CritterZone air purifier.

  • Grady
    on Mar 5, 2015

    Penny, a cat may have peed in your car. So check for signs of actual pee.

  • Grady
    on Apr 7, 2015

    I think that maybe you need new carpet or just get a purifier. This problem happens to many people. I really hope you find the cause.

  • Grady
    on Apr 9, 2015

    Mold can easily cause this smell. Check for mold.

  • Darlene Ranaudo
    on Apr 10, 2015

    We are still having this issue and our builder is recommending putting in an exhaust fan similar to what is used in Radon mitigation. I am requesting to just do the radon mitigation which involves piping under the plastic to catch the off gassing before it enters the crawl and pulls it out and up. I would rather do this then just mitigate the smell in the crawl. Catch it before it gets there. Hey who knows, now wouldn't have to worry about Radon. Not sure what else to do as no one seems to have a solution but hearing more and more cases.

  • Jeff
    on Apr 10, 2015

    Have you considered ripping up the encap? We have. It's such a nasty smell and now going on 2+ years.

  • Grady
    on Apr 11, 2015

    That is an excellent idea, Darlene.

  • Paul Adams
    on Apr 11, 2015

    @Jeff Did you pull up he encap?, We thought about ripping up the plastic. Wondering if the mold will come back .

    • Paul Adams
      on Apr 14, 2015

      I have put a PVC pipe on the out blowing end of the humidifier and vented this to the outside and the smell is not near as bad now. This isjust a temporary fix and I have probably voided my warrenty. However the contractor did not know what to do,and something had to be done. Surely someone has an answer.

  • Mary Take Massieon
    on Apr 11, 2015

    Another one is Bat guana. I had bat's in the upstairs attic and yes it is possible.

  • Paul Adams
    on Apr 20, 2015

    @Mary Take Massieon , Having Bat Guana in the attic is different then the smell that comes from the crawl space after it has been encapped.

  • Grady
    on May 7, 2015

    Try remodeling the crawlspace and see if that takes care of the problem. Do you have a dog door? Maybe a cat is sneaking through their and urinating in your crawlspace.

  • Paul Adams
    on May 8, 2015

    @Grady, Why would I have a dog door in the crawl space of my home? Do you have one in yours?

  • Grady
    on May 11, 2015

    I do not have a dog door at all, I should, though. I don't have a crawlspace. And do you just have a dog door in general?

  • B. Enne
    on May 19, 2015

    If there was ever cat or mouse pee in your crawl space, humidity would reactivate it. I have the same problem in my basement in one spot. Although we see nothing under black light, we occasionally get a waft of cat pee in one corner, where cats peed over 20 years ago...the spot was sanitized etc., but it still comes back to haunt us. Could it also be the plastic used to encapsulate?

  • Gary L
    on Jul 20, 2015

    Just posting an update on the issues I reported earlier in this thread. In late January I cranked up my dehumidifier in the crawl space to “constant on”. I left it that way for about 3 weeks. I then set it back to the max high setting which allowed it to cycle. Either way it ran a lot. I keep pretty close watch on my electric usage and it definitely had an adverse impact. The good news is that as of today some 6 months later, we have had no “cat urine” odors in the house this season. The installer was out here for my annual service about 2 weeks ago and I stuck my head into the crawl space. There are none of the foul odors present. It appears that what the area needed was a good drying out. My next step is going to be to bring the dehumidifier back to a more normal setting to see if the odors stay away and the electric usage falls back in line.

  • Mal2562924
    on Oct 8, 2015

    I recently had the crawl space under my house encapsulated and 30 days later I noticed a cat-piss smell like. To make a long story short!!!! The smell comes from the plastic used. I conducted an experiment and took a 24 X24 inch piece of the same plastic and put it in large glass jar and capped it. After a few days I opened it and the smell that came out of that jar was just as the cat-piss smell from the crawl space. Most all plastic will have that same smell… Solution to the problem! I insulated the floors with fiberglass insulation, put the plastic “only”on the crawl space ground and open all the vents to the crawl space. Problem solved!!! Crawl space capsulation looks good and supposed to keep the heat in thus heating your floors, venting the crawl space is the key to rid of the smell...

    • Camille Radich
      on Oct 9, 2015

      Great solution. We had our space encapsulated, same issues. I recently spoke with a second space encapsulation company who shared with me they had encountered the same issue with off gassing from the plastic Clean Space uses. I like your solution, I'm going to give it a try! Off gassing is toxic.

  • Mal2562924
    on Oct 8, 2015

    I recently had the crawl space under my house encapsulated and30 days later I noticed a cat-piss smell like. To make a long story short!!!!The smell comes from the plastic used. I conducted an experiment and took a 24 X24 inch piece of the same plastic and put it in large glass jar and capped it. Aftera few days I opened it and the smell that came out of that jar was just as thecat-piss smell from the crawl space. Most all plastic will have that same smell… Solution to theproblem! I insulated the floors with fiberglass insulation, put the plastic “only”on the crawl space ground and open all the vents to the crawl space. Problemsolved!!! Crawl space capsulation looksgood but not worth it due to the smell

  • Dla2590020
    on Oct 10, 2015

    Oh my gosh this could be our problem. We had the basement encapsulated at our office last year and I have been chasing down the cat urine odor ever since. Yesterday we had someone go down in the crawl a space and he said he smelled a cat urine odor. Now I have to figure out what to do since I am a renter.

  • Mrsmmcs
    on Nov 6, 2015

    Wow..I'm in Nolensville, TN and am having the same issue. We bought a 6 yr old house & noticed a cat urine smell in the house..the previous owners did not have cats, but therte were a couple feral cats hanging around the first few months after we moved in, so they may have been feeding them. The smell seemed to be coming from the floor vents on the main floor, so we had the ductwork cleaned. Then had the crawlspace encapsulated after pulling out all of the old insulation, dead mice, etc. That seemed to take care of the smell about 80%, but about a month ago it's back, stronger than ever. A bit stronger in the crawlspace. No mold or mildew visible on the joists, etc. So maybe now the plastic is the culprit? If so, I can't figure out why the smell was basically gone for about a year, and now is back worse than ever. Very frustrating!

  • Grady
    on May 2, 2016

    I suggest to steam clean the carpet, get new carpet, or just move to a different house.

Your comment...