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Odor from Crawl Space

56K views 68 replies 18 participants last post by  beenthere 
#1 ·
Thanks in advance for anyone who can help! :thumbsup:

I purchased a house in central NC at the end of January 2012. During home inspection, we discovered a mold problem on the floor joists. We had a professional company come in and treat, kill, clean, etc. the mold. We also had a conditioned, sealed crawl space installed. The installer used a 20 mil vapor barrier and Thermax(TM) board insulation for the walls of the crawlspace. There are vents and returns along the main trunk line as required by code. The installer placed a humidity monitor in the crawl space that I can check and everything seemed be correctly done.

Now for the rest of the story and my reason for posting...

The next three days after the sealed crawl space was installed was horrible inside my house. There was an extremely strong odor like an earthy, musky smell. The installer thought that it was off-gassing from the materials in the crawl space and possibly the moisture that remained. "Give it a week."

A week goes by and the odor remained. I then placed a squirrel fan at the crawlspace door blowing out. The fan remained for about 5 days and the smell seemed to lessen. The installer placed a dehumidifier in the crawl space and said give it a little while longer.

Two more weeks, the smell lessened more but still was noticeable. As it was an unusually warm March in NC, we moved our stuff in the house and opened the windows to air it out. The heat was off during this time. Meanwhile, the installer taped the crawl space vents shut and installed a vent fan blowing out of the crawl space. Over the next few weeks, the odor appeared to be getting better. However, when a cold snap came through, the windows had to be shut and the heat turned on. The smell returned. The installer made sure all HVAC ducts were taped, the vapor barrier was rechecked, and the floor vent boots were sealed with a puddy that hardens from the crawl space side of the boot to limit leaks into the house.

The smell is still very noticeable inside my house. If you go to the vent fan blowing out, the smell is much stronger due to the concentrated air blowing out of the crawl space. We have triple checked the floor joists and they are bone dry (no moisture problem there). The humidity levels inside the crawl space and house are normal if not a little on the dry side (around 30-40 RH). We cut a small place in the vapor barrier and checked the soil under it, it too is dry and does not smell out of the ordinary. The HVAC ducts have been fogged, cleaned, and the coils cleaned on the unit. There is not any standing water anywhere in the crawl space.

I am my wits end here! Here are the facts I can tell you:

1. The floor joists had mold on them before the sealed crawl space was installed but there was never any smell inside the house before the conditioned crawl space was installed.
2. The HVAC ducts remained after the cleaning of the mold and were not replaced.
3. The odor was the strongest 1-4 days after the install but still remains.
4. To the best of my knowledge, there is NOT a moisture problem in the crawl space.
5. We have tried HEPA filters and an Ozone generator inside the house but not in the crawl space.
6. The installer did a follow up air quality test and there was less than the average household mold or spores in the air.
7. The odor seems to be worse when the heat is turned on.
8. The vent fan outputs this strong smell whether the HVAC is on or off.
9. We have taken samples of the vapor barrier, Thermax, and floor joists; none of which seemed to produce a smell when placed in a container and allowed to heat up with outside heat.
10. I AM IN DESPERATE NEED OF HELP TO SOLVE THIS PROBLEM!!! :furious:

Thanks for taking the time to read, please let me know if you have had a similar experience or can offer any suggestions!

Gary
 
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#45 · (Edited)
Similar experience.

Gary, I am having the same issue. It sounds like you have done an excellent job of sealing the crawlspace. I would appreciate another update from you.

I encapsulated my 1,300 sq. ft. crawl a few months ago, including eliminating the foundation wall vents and installing a supply and a return vent in the HVAC to condition that air. The cat pee smell started slowly, then got worse and worse.

BTW - my crawl humidity has hovered around 68%.

I talked to Larry at Crawlspace Concepts, a supplier of liners, etc. A very knowledgeable guy. He said the cat piss smell is usually soil gas. I don't understand exactly how it happens after the liner is installed. He did suggest slitting the liner in a place or two and sticking my nose down there and taking a whiff to verify. (Gary, I know you did this and didn't smell anything other than dirt).

Larry suggested installing a soil gas mitigation system. The idea is to pull the gases under the liner, out of the house. You use 4" perforated drain pipe and a radon mitigation fan. The idea is, you slit the liner and slide some of these lengths of perforated pipe under the liner. He said you don't even have to glue them them, it's okay to just butt them together. The stuff is fairly cheap.

Here is a link to their blog article: http://crawlspacerepair.com/blog/crawl-space-soil-gas/

Create some sort of array, perhaps along the walls. Connect the radon fan and duct it all up and out of the house. Through the roof might be the best. Larry is in the process of sketching up the array for me and we will probably be doing this installation within the month. We may also be purchasing a crawlspace dehumidifier.

I'm attaching Larry's sketch of my crawlspace, and his recommendation for the layout of the perforated drain tubing. Not quite sure yet where I am going to connect the radon fan into it.

One other thing that may have been a factor. We noticed the evaporator coil in the heat pump air handler was not channeling the all condensation and it some would drain out onto the garage floor. The interior of the air handles is lined with fiberglass, so I thought perhaps mold was building up there. Lots of side issues here, but the bottom line is it's a lousy air handler design. (20+ y.o.).

One person on the HVAC section of this site suggested cleaning the evaporator coils to eliminate the dripping. Well, they looked just fine, but I bought a can of foaming coil cleaner from our local HVAC distributor. Sprayed it on, and didn't think it would work. Well, it's still dripping, but suddenly the smell is reduced. Maybe there was mold build-up on the coils, though I sure couldn't see anything. Go figure, but if I stick my head in the crawl, I still smell the cat pee.

So, the first thing on our list is to do the soil gas remediation. If that doesn't work, we will install a good crawlspace dehumidifier (may do that anyway).

Appreciate any updates.

Sam
 

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#47 · (Edited)
Yes, it worked. Within 24 hours, after we turned the fan on, the smell in the house was gone and it was fairly easy to do.

I installed the system, pretty much as shown in the sketch in my previous post. I took a Tee off at the center of the array. From there I used solid 4" PVC and ducted it horizontally into the adjoining garage, then on up. I installed the radon fan in the garage attic, then vented it through the roof.

The other day I stuck my nose into the rain trap I built in, to see if the odor was still present in the exhaust air. I thought perhaps that a month of running the fan would have removed the smell, but yes, it still stunk. The system is an unqualified success.

I do wonder if pulling the air out from under the crawl space will affect our utility bills. I guess that verdict is out for the moment.

Murph
 
#50 ·
I don't think they're trying to imply any kind of true "ventilation" of the crawl space, but more of an "evacuation" of off-gassing from the earth under the vapor barrier. Tthey are only using a small radon gas fan to help create a chimney effect through some PVC vent piping.

Sounds fairly promising so far....
 
#55 ·
Hello to everyone again

I am sorry I have not updated anyone in quite some time. Basically, a year has passed and there is no smell in my house. However, the smell in the crawlspace remains. I have two crawlspace vent fans blowing out continuously. My installer wants to try something similiar to the diagrams mentioned before (I think it was MurphyMan). I will update as soon as possibe.
 
#56 ·
"Still, I know there is still some leakage between the liner and the foundation. For example, there are about 8 support pilings made of cinderblock. I know there is leakage there, due to the irregular shape of the end of the blocks and other places."

There should not be any air leakage anywhere regardless of the "irregular shape" of anything. Special air sealing tape exists for that purpose. It will stretch/conform and truly seal almost any surface. As far as to exactly what the smell is that gets tricky but check this list it might help you:http://mycrawlspace.net/mycrawlspacestinks.aspx
 
#57 ·
It's the liner

Sad to say but we have had the same experience. We used the 10 mil diamond back liner from crawlspace repair. It took me two years to figure out it is the liner. On their site they refer to it as the mysterious stinky crawlspace odor. They also say it is a reaction of the plastic with gases in the soil. I can debunk that theory. I recently ordered some scrap as we decided to add another sump pump in our crawl. I had cut the piece I needed on the drive and left the scrap out there for a few days. I felt certain when I collected the scrap a few days later that a cat had sprayed on it. I threw it away which bummed me as it was so expensive. A water guy and I were chasing down an issue and ended up in our crawl near the newly patched spot and we both looked at each other and said cat pee. Again, thought a stray cat got in the crawl as I had left it open once overnight. Still did not dawn on me. Finally had a thought and called crawlspace repair and they told me that yes they have had this issue and directed me to articles on their site and how to treat it as radon mitigation to evacuate the odors from below the plastic. I considered this for a week as we may have a radon issue and need to retest. Finally I decided that I had absolutely no interest in trying to make their product work for me. There product had literally brought some of the most longterm hardship I had ever experienced and that says alot. I felt that their article about some homeowners removing the diamondback liner and putting 6 mil down and that the odor was worse than ever was probably misleading. They said the people went back to the diamondback with the same previous odor level again and did the radon mitigation trick. I have spent the past week removing all the diamondback I installed and boy did it stink. But after I removed it, smelled like mold, personally better than cat pee, although I would say that our older original diamondback plastic smell graduated to dead wet worms. Anyhoo, I laid regular 10 mil plastic down and it smells like plastic, so much better. Frankly i was afraid to order anyones higher grade plastic as i was fearful of the same odor event occuring. I'm sure this will gradually outgas. Last night I was covering my last room and had to remove the sump pump lid and check valve. I had cut a circle around it when removing the diamondback and I had a doughnut cut piece of diamondback I had to remove, man, that odor was horrendous. Amazing what one little scrap can do. I had not smelled that in over a week and I so did not want a reminder. Trash day was a miracle, I removed everything the night before.

In the two years of trying to figure out this odor, I had tried sooooooo many things. Sealed every single bit of hvac boots, replaced the trunk line, resealed the runs with mastic and double zip tied, cleaned the coils, cleaned every surface of the plastic multiple times, caulked any seam down there, used zinnser on any exsposed wood, pitched a year old dehumidifier, bought clo2 packs to hang in the crawl, used concrobium vapor, bought a crawlspace fan for one of the vents, ran a ton of carbon cleaners, an ozone generator, ripped up every floor board upstairs and caulked, sealed all vents upstairs as well as the fireplace and STILL that odor would make its way into our home. I am sure I have not remembered everything we have done. I have spent a fortune as well as a freakish amount of time trying to fix this and it ended up being the liner. Funny, their site says American made, no vocs and no outgassing. They said all the right things and it was one of the biggest mistakes of my life.
 
#58 ·
Reply to Terrik

Hello everyone, my name is Matt Leech and I am the president over at crawl space repair. I was alerted to Terrik's post by one of the chat room users, so I thought I would stop by and join in.

I would like to start with a short reply. Because we have chat names I don't know who Terrik is or if he/she even bought anything from us. First, we have not received any complaints of a stinky crawl space from a customer that purchased our DiamondBack product and second we have never made a 10 mil in any of our product lines. In Terrik's post it states "They also say it is a reaction of the plastic with gases in the soil". This statement is not true. Our article states the odor comes from the off gassing of organic material breaking down in the soil. That off gassing does not react with our plastic to make an order, that is the odor. To support my claim I will point you to an article written by Christopher M. Gray, Russell K. Monson, and Noah Fierer entitled "Emissions of volatile organic compounds during
the decomposition of plant litter" and it can be found here-http://www.colorado.edu/eeb/EEBprojects/FiererLab/Gray_2010_VOCs.pdf.

It is true that encapsulating a crawl space gets blamed for this odor, mostly because it is not as pronounce prior to sealing the crawl space. We know that soil gas mitigation, done properly, eliminates this problem 100% of the time. Please note that it must be done properly or there will be little improvement.

I find it curious that Terrik tried all those things that are listed in the post but did not try the mitigation system that is recommended in our article.

Even though I believe this is a competitor trying to bash our products, I would like to offer Terrik a refund. I certainly do not want unhappy customers. Terrik, if you would please supply your order number or a copy of your receipt I will be sure to issue you a refund of the DiamondBack that you were not happy with.

If anyone would like to ask us a question on the crawl space odor and how to get rid of it please contact us through our site crawl space repair.
 
#59 ·
Hi Matt,

#CSC-53380 for $693.93, I was wrong, 8 mil and 12 mil remnants, tapes, caulk, fasteners, and brush etc.....

#CSC-56768 for $344.58, sump set, 12mil diamond back scrap and tape

I hope you would refund the install components like tapes, fasteners and caulk as well. They were ordered to install your product per recommendation.

Matt, I have a suggestion, cut a 3x3 piece of the 12 mil plastic and take it home. Toss it in the backyard for 3 days and bring it in to warm up and see if you detect the odor. I think the odor itself is in the silver or black backing and is moisture activated. I read your voc article, no where did it say the soil gas smelled like cat pee. Regardless, our crawlspace is probably two to three feet below the plow zone and as I have dug down there to install two sump pumps I only saw gray clay, no vegetative decay, no roots, nothing, no cat urine smell, but definitely moldy. I feel confident as I'm an archaeologist. For that matter, we have been in our home 12 years. We did pull up the old 6 mil plastic ( 20 years old) and laid new 10 mil regular plastic down on the floor only probably five years ago, it did not produce this odor.

The recent 12 mil scrap smelled like urine just from sitting on the drive. I feel we both FIRMLY believe what we are sharing. I truly believe we are both nice people. For that matter every single person I have ever spoken to there has been lovely. I did call three weeks ago and asked about the odor,in fact, i think you were busy at the time and you told someone how to install the pvc and he passed it on to me. I had intended to send you a letter once my refurbish was complete. I actually ordered fasteners from you two weeks ago and it HURT, I just could not find them anywhere else. I just felt so bad for those people as I have lived it as well and I posted a response.

I dont find it curious. In regards to to installing your radon mitigation technique, I read the review by Sam Hoskins on your site for the sump pump kit. He said it cost him $350 for the radon fan and pvc plus another $200 to pay someone to cut holes thru the roof and vent it. Frankly, as I stated above, I considered it for a week, and it is the principle of the matter. I do not want to spend another $550 to make your product work. I'm sure I have spent over $700 already plus my labor trying to fix it. I feel so foolish that I did not recognize the source sooner.

Of note Matt, these people having this issue have resorted to opening their crawlspace and installing fans to exhume the constant odor. I'm not so sure the odor is created by sealing the crawl rather it is still there while opened and with fans running just helps to keep it from coming into the living area. I also believe the stack effect bites. I've had two job offers, it looked so damn good. I can't believe I am doing this again.

By my order number you should be able to track me down. Call if you wish. I will be nice.
 
#60 ·
So I looked up your order and I see you purchased one roll of 12 Mil DiamondBack, which I will refund as I stated.

Although you continue to state that the plastic was the cause of the odor, that does not make it fact, is based on one case judged and juried by you and will not convince me because you installed a sump basin and did not see any organic material that you would blame for the odor. Believe it or not, we would have been out of business years ago if we were making and selling stinky plastic, besides my 12,000 sq foot warehouse would smell like cat pee and customers would smell it before they installed it. We make 1000 rolls at a time, if it is the plastic then that means there are more than 500 customers with the same 12 Mil DiamondBack liner that was installed in your crawl space that has an odor problem as well, yet this is the only complaint. There would be write up after write up about how stinky our products are, but there is not. The most you will find is uneducated consumers that blame the last thing they bought as the problem rather than the installation quality and method and that goes for any liner brand. In fact, in the industry, EVERY crawl space liner has been involved in a stinky crawl space and be sure that not all liners are purchased from us. Of the tens of thousands of rolls of liner that we have made and sold there has been less than a dozen cases of a stinky crawl space and the customer was able to eliminate the odor 100%, 100% of the time, just look at the customer reviews. That's about .02%, not 2% but .02%, of our customers homes that have a soil gas problem. All that being said, you have found who to blame.

I know what I say is just my word, but if I were a liar and cheat I would not care what you think or say and I certainly would not give you a REFUND based on your word.

Matt
 
#61 ·
Well Matt, if you wanted to be honest we spent approximately $600 on the diamond back liner, not the cost of 1 roll of 12 mil liner. You did not specify which size, could be from $200 - $320.

I did misquote the second invoice, I did not have the remnant added on there.

I would be upset if someone maligned my product as well, this is how you make a living. I would agree that I did see that another liner company has had some odor issues as well. Again, I believe it is the black or gray side of the liner that emits the odor and I did not smell it until it was unrolled and had a humidity reaction from sitting on our drive for a few days. I would assume your warehouse is climate controlled and the rolls are rolled white facing outside. It's a simple thing to try the test I suggested. I would even be willing to send you half of my sump pump liner cookie for reference:). Truly I did not jump to the conclusion that it was your liner, it was by happenstance since we needed to patch a spot and bought new liner. When I removed everything I let it air down there a week. I could smell some of the residual cat odor in the 2 inch blue board I installed and am hopeful I aired it out long enough. It was mostly lingering at the entrance and crawlspace vent where we had fans drawing the odor out for the past year. I can say we certainly don't have that odor any longer so that tells me all I need to know right there. Terri
 
#62 ·
Polyethylene is milky in it's uncolored state. White is as much a colorant as black and gray. So, if the black or gray color were the cause then the white would give off the same smell.

Our products are rolled back side out/white side in. Again, if the gray or black was the cause then my warehouse would smell like cat pee as well as the UPS truck and all customers garages. To confirm, watch this youtube video that shows how our products are rolled- http://youtu.be/tVS81yIji50

My warehouse is not climate controlled. Anyone is welcome to stop by for a sniff.

Teri, you are not the first person to blame my products for a soil gas problem, so that is not what erks me. What leaves me shaking my head is that we helped you and then we helped you again. From selling you small pieces so you did not have to buy a full roll (from us or anyone) to the time spent talking with you guys about your problem and giving you the PROVEN solution. You refused to employ that solution and instead try more than 15 of your own ideas, while spending more money than the actual solution would have cost you because it was the "principle of the matter". Then, when everything you thought of didn't work, you go to a DIY chat room and (as you say) "malign" my products and my company. Your attempt to discredit our knowledge of the industry and plastic in general, because we have something to sell, is spiteful. So, who knows more about prehistoric people, a plastic manufacture or a archaeologist?

So ya, that's what erks me. :(
 
#63 ·
We have 1500 sq feet, 511 was for the walls in remnants, 1000 sq foot roll for floors. We have two identical sides to our crawl and both floors had a single cut piece from the roll. Jessica worked with me and did a great job of piecing it together for us so we would not have 500 sq ft left over. It seems very obvious to me that you do not know what we bought. Our remnants were 13x16, 13x8.5, 13 x7, 13 x5.5, 12x6.5 and 11x7.5 which equals 511.50 sq feet in 12 mil and. 1 roll of 8 mil. I'd say we were doing you a favor as well using remnants. The remnants were not cheaper, same cost per sq foot.

I just found out about your remediation for evacuating the odor three weeks ago. After I had spent a fair amount of money trying to cure the problem, not knowing the source of the odor. Don't make it sound like you offered me a solution long ago and I vehemently rejected it on principle. We have had this issue for almost two years.

Matt, I don't know the magical answer here, i just know what we experienced, how we experienced it and other posts I have been able to find of other people who have had this issue as well using reinforced liners, not regular plastic liner. I'm not spiteful. You don't even know me. I am 47 years old, 5' 4 1/2" , 127 pound woman with Multiple Sclerosis who spent two months in the crawl doing prep work then installed your product. All of this two months after having a six inch incision in my abdomen. The only thing I could not do was use the hammer drill, my husband who works 70 hours a week did so. I don't feel my parts so well any more but thankfully they still work and muscle fatigue is somewhat of an issue. I'm not allowed to use the chain saw anymore:)

I was born with joy. I still have joy and I am blessed beyond reason. But I can tell you that my joy has been tapped severely. Who should have to live with their home smelling of cat urine. As I have installed 10 mil plastic liner and no longer have the cat urine odor, how could I have not made the right choice? If it were soil gas, wouldn't ANY liner produce the same affect? It cost me $300.

I'll let the readers know if you actually hold to your word and refund us and if it was the true amount we spent on the diamond back liner. I didn't quite know how to word that in a nicer manner, sorry. Terri

Ps, I am a historic archaeologist
 
#64 ·
Terri,

I have calculated what DiamondBack liner you actually purchased from my company and it comes to $495. BTW, the full roll was 12 Mil DiamondBack not 8 Mil, and the remnants were also all 12 Mil, no 8 Mil. I feel you need this correct information to understand the refund, please review your receipts. I do find it a bit funny though:laughing: that you stated "It seems very obvious to me that you do not know what we bought". However, I am a bit lost at how you come to $600. But, I am sure no matter what amount I refund, you will not be happy with it. Please remember that I was the one that OFFERED the refund and no one is making me do it. So find joy in that.

Please accept the amount of $495 gracefully

or

Reject it with another complaint and we will go our separate ways...

I will wait your reply.
 
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