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Old 07-26-2010, 12:30 AM   #16
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Bad smell in crawl space.


The insulation is gone from the SW corner of the crawl. As you can see, we had some nut-eating critters hanging out up in/above the insulation.

We had a very cold winter this year. That must have driven the mice, or whatever, into our crawl space for warmth. While there, they must have peed quite bit. That is the likely source of our original urine smell.

They spent most of their time in two spots, both pretty close to the crawl door. That was their most likely entry point. There were minor caches in five or ten other places, farther from the door.

I have been intending to make a new, better fitting door - but haven't gotten around to it. For now, I just spayed some foam sealant in all the gaps, pipe openings, etc.

Does anyone know, based on the debris, what kind of critters we had?

The smell down there may have diminished a bit since I took the insulation out and cleaned out all the debris. I will give it another sniff tomorrow to be sure. But, I don't think its all gone.

There must be some smell stuck to the radon barrier. Its not the original urine smell, so I'm going to need some new odor remover ideas. The bacteria/enzyme solution stopped the urine smell with one application, but I'm wondering if it caused this newer smell.
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Old 07-26-2010, 11:14 AM   #17
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Bad smell in crawl space.


From what I see of the debrie, my guess would be small, brown squirrels. Chipmonks burrow in the ground and store their food down there also.
My neighbor had these squirrels get into his garage where he had his boat stored. They filled the boat with walnuts and chewed the canvas in many, many places. Very destructive, these little varmints!
My crawl space entrance is similar to yours and I sealed around jamb with expanding foam that was effective for keeping out the cold and the mice.
Rather than insulate the floors, as I see at your place, I insulated the foundation walls.
We have Roxul bat insulation readily available in Canada and I used this, held in place by insulation pins.
Roxul is fire rated and doesn't absorb moisture.
In your case, I would seriously consider insulating the foundation wall, rather than the over-head floor. Its much simpler to do. Using insulation pins, glued to the wall, just push the bats onto the pins. Press the vapor barrier over the insulation, and then use pin locks to keep everything in place.
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Old 07-26-2010, 01:00 PM   #18
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Bad smell in crawl space.


Quote:
Originally Posted by Wildie View Post
From what I see of the debrie, my guess would be small, brown squirrels. Chipmonks burrow in the ground and store their food down there also.
My neighbor had these squirrels get into his garage where he had his boat stored. They filled the boat with walnuts and chewed the canvas in many, many places. Very destructive, these little varmints!
My crawl space entrance is similar to yours and I sealed around jamb with expanding foam that was effective for keeping out the cold and the mice.
Rather than insulate the floors, as I see at your place, I insulated the foundation walls.
We have Roxul bat insulation readily available in Canada and I used this, held in place by insulation pins.
Roxul is fire rated and doesn't absorb moisture.
In your case, I would seriously consider insulating the foundation wall, rather than the over-head floor. Its much simpler to do. Using insulation pins, glued to the wall, just push the bats onto the pins. Press the vapor barrier over the insulation, and then use pin locks to keep everything in place.
Wildie,

We have lots of gray squirrels and brown chipmunks here. The squirrels seem too big to fit the cracks I used to have. Still, with all the nut shells I found, squirrels were the first kind of critter that came to mind.

I checked out Roxul. I can have it special ordered by the local Home Depot.

A picture or a link would help me understand how the insulation pins/locks work in conjunction with the Roxul and the vapor barrier.

I would have to figure out how to "interface" the vapor barrier on the crawl walls with the radon barrier.

Do you "supply" any conditioned air to your crawl?
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Old 07-26-2010, 01:02 PM   #19
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Bad smell in crawl space.


I'm on a different computer and logged in under a different user name. I need to switch this one over to John_W to be consistent.
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Old 07-27-2010, 10:44 AM   #20
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Bad smell in crawl space.


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Originally Posted by john-hvac-new View Post
Wildie,

We have lots of gray squirrels and brown chipmunks here. The squirrels seem too big to fit the cracks I used to have. Still, with all the nut shells I found, squirrels were the first kind of critter that came to mind.

I checked out Roxul. I can have it special ordered by the local Home Depot.

A picture or a link would help me understand how the insulation pins/locks work in conjunction with the Roxul and the vapor barrier.

I would have to figure out how to "interface" the vapor barrier on the crawl walls with the radon barrier.

Do you "supply" any conditioned air to your crawl?
Unfortunately the place where I insulated the crawl space is at the lake. Its well over an hours drive and due to my wife's health condition, I have been limited on my visits there, this year!
However, I used the same method for my daughters basement and I'll try to get there and take a pic.
There is a discussion on this site already, that I responded to that you may like to read. Insulating an unheated crawlspace

I had a new furnace and a/c installed in 2000 and I had the installers install a 6" duct to feed the crawl space and vent return to complete the circuit.

To interface the vapor barrier to the radon barrier, I would think it wise to provide a separation between the two. Pehaps mount a 1X2 on the wall, an inch or so above the radon shield. Then staple the vapor barrier to this.
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Old 07-22-2011, 10:18 PM   #21
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Bad smell in crawl space.


Hi John,
I'm new to this post and I've read your post about cat urine smell coming from HVAC when AC is on. I have a similar situation in my 1000 sq ft condo, air ducts/intakes running through the crawls space, vapor barrier installed on floor and up the walls, fiberglass batt insulation between floor joists, etc.. Whenever I turn on the AC you smell cat urine, when its off u don't. All the foundation vents are closed and no visible signs of moisture except some puddles like you saw but eventually dried up, some yellow in color. I placed odor eaters, damp eaters, lava rocks in the crawl to try to rid this smell. I wanted to ask if you came to a solution to rid the urine smell in your home?
I was thinking that if the insulation that covers the air ducts under the exterior foil covering gets damp or wet, might that smell of cat urine? BTW: my HVAC is a packaged unit that is outside.
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Old 07-23-2011, 03:07 PM   #22
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Bad smell in crawl space.


Quote:
Originally Posted by Andy_39 View Post
Hi John,
I'm new to this post and I've read your post about cat urine smell coming from HVAC when AC is on. I have a similar situation in my 1000 sq ft condo, air ducts/intakes running through the crawls space, vapor barrier installed on floor and up the walls, fiberglass batt insulation between floor joists, etc.. Whenever I turn on the AC you smell cat urine, when its off u don't. All the foundation vents are closed and no visible signs of moisture except some puddles like you saw but eventually dried up, some yellow in color. I placed odor eaters, damp eaters, lava rocks in the crawl to try to rid this smell. I wanted to ask if you came to a solution to rid the urine smell in your home?
I was thinking that if the insulation that covers the air ducts under the exterior foil covering gets damp or wet, might that smell of cat urine? BTW: my HVAC is a packaged unit that is outside.
Hi Andy,

Sorry to hear you have that problem.

Is the smell apparent to you when you are in the crawl? Is it localized anywhere? Do you get the smell year round? Have you tried putting a dehumidifier in your crawl?

Our smell is definitely originating in the crawl, not inside the duct work or up in the house. It is 'activated' by high summer humidity and is only sucked into the HVAC system when the blower is at top speed.

There is no complete fix yet. The smell went mostly dormant sometime in the fall and didn't come back until two weeks ago when we got the really heavy summer humidity back.

Several guys have said that damp insulation can smell like urine. But I donít think that is happening in my case.

For more on my current situation and thinking see Current Details, below.


Things that have helped:

Low relative humidity. Winter, late fall and early spring do this for us naturally. A dehumidifier and a sealed crawl would probably do it for us in the summer.

When the blower is in circulation mode, and the heat pump is off, the blower runs with less force, so there is less suction Ė and very little, if any, smell gets sucked into the HVAC system.

Pulling air out from under the house, in that corner. I used a box fan. There is probably a picture of that earlier in this thread.

Hanging bags of Earth Careís Odor Remover near the place where the return air duct meets the HVAC equipment. The odor seems to be getting into the HVAC system at that junction, even though a smoke test reveals no hint of a leak. The bags suck up some of the smell before it can get into the HVAC system.

(http://www.cleartheair.com/english/p...or_bag/13.html)


Things that didnít help:

The UV light and UV protection glasses didnít turn up any obvious, localized urine or dead animal residue. They do show an almost uniform scattering of faint, small spots on the upper side of the duct work Ė everywhere, not just in that corner. It shows rather strong glowing residue on the tin termite shield Ė but more on the underside than on top, and just as much far from the corner as nearby. Both of these phenomena seem more like the work of insects and/or material properties.

The odor eliminator chemical sprays were probably worse than useless. The first one changed the odor from urine smell to something else that was worse Ė and seemed to make things stink that hadnít before, like the insulation between the joists. The subsequent sprays did nothing.

Keep us posted on your efforts and results. Good luck.

John


Current Details:

Once again, this summer, the smell is localized to the same 10x10 corner near the crawl door.

One change from late last summer is that it is a URINE smell again and not the other smell. So the cause must be one of these:
  1. fresh urine
  2. the urine killing, spay-on chemicals don't work
  3. something else is causing the smell

Fresh urine?

Last fall, I used spray foam and otherwise blocked every conceivable entryway. Only things smaller than a gnat can get into the crawl now. I have also been careful not to leave the door open while I am working under the house. So I don't believe this is a new load of urine.


Something else?

The smell is definitely Ďactivatedí by high relative humidity. There are open, screen covered foundation vents in that end of the crawl so humid air is free to move into the crawl.

I don't think the humidity is causing the insulation in that corner to get damp enough to smell. There are no puddles or sweating ducts in that corner - never have been. There isn't any insulation between the floor joists in that corner since I never replaced the stuff I pulled out last summer.

Several guys have said that damp insulation can smell like urine. But I donít think that is happening in this case. Even in the parts of the crawl where we had sweating ducts and actual rainfall last year, there was never a urine smell. And those areas have all the same types of ducts, plastic ground cover and between-joist insulation that is/was in our smelly little 10x10 corner.

Also, nothing about the materials, ducting or structure of that corner, or the environment outside, changed from the previous summer (two years ago). So itís not very likely that the crawl suddenly started smelling all by itself.


The spray-on chemicals don't work?

This seems most likely. The urine smell started 'suddenly, last summer'. (I think there is a book or movie with that title, but probably isn't a horror story about killer urine smells.)

I think that urine smell was Ďput thereí two winters ago and it was Ďactivatedí when the summer humidity arrived. It's remotely possible that a neighborhood cat snuck in and peed while I was under the house doing some work, with the door open.

But, since I found evidence of lots of rodent activity during last summer's 'battle' with the smell - I conclude that THEY did it. I think rodents peed all over the place in that corner two winters ago. Their pee must be very potent, long lasting and is activated by high humidity.

However, I donít understand why it doesnít show up under UV light.

Maybe there is some other cause.

In any case, Iíve wasted enough time on this thing. Iím not going to try any more direct smell removal stuff besides the Odor Remover bags. With them, it only smells moderately bad in late afternoon and early evening, in the summer, when the heat and humidity are highest.

I am going to try closing the vents and running a dehumidifier in that corner. Its an expensive, noisy fix - but one that will be good for the entire crawl/house, not just that corner.
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Old 07-24-2011, 02:35 PM   #23
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Bad smell in crawl space.


I appreciate the info John! The same here the smell is activated with high humidity, I am in the northeast so right now is 70-80% humidity. In winter it goes away.
I've stuffed insulation in the foundation vents so humid air doesn't come in, I think one of the best things I did, before everything got sweaty.
I left one vent half open for some air circulation and in one vent I installed a foundation vent fan. Its a small fan maybe 6-8" diameter but it fits into the foundation vent opening and has a regular 3 prong plug. You can search on Internet for foundation vent fan, I bought it a while ago so I don't remember the website. It pulls some of the air from crawl to outside. I threw odor eater lava rocks, damp eater things none of those seem to work. My crawl is sealed only entry is thru the floor so no animals can get in/out. Chat soon,
Andy
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Old 07-24-2011, 08:27 PM   #24
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Bad smell in crawl space.


Quote:
Originally Posted by Andy_39 View Post
I appreciate the info John! The same here the smell is activated with high humidity, I am in the northeast so right now is 70-80% humidity. In winter it goes away.
I've stuffed insulation in the foundation vents so humid air doesn't come in, I think one of the best things I did, before everything got sweaty.
I left one vent half open for some air circulation and in one vent I installed a foundation vent fan. Its a small fan maybe 6-8" diameter but it fits into the foundation vent opening and has a regular 3 prong plug. You can search on Internet for foundation vent fan, I bought it a while ago so I don't remember the website. It pulls some of the air from crawl to outside. I threw odor eater lava rocks, damp eater things none of those seem to work. My crawl is sealed only entry is thru the floor so no animals can get in/out. Chat soon,
Andy
You should seal the crawlspace up as tight as possible, summer and winter. Humid air must be prevented from crawl spaces in our northern climes.
When humid air cools in the crawl space, it gives up its moisture and it condenses on cool surfaces. This moisture feeds the growth of mold.
If necessary, seal it up and heat it with an electric heater, so that there are no cool surfaces that moist air can condense on.

Last edited by Wildie; 07-24-2011 at 08:31 PM. Reason: Grammar
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Old 07-24-2011, 10:15 PM   #25
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Bad smell in crawl space.


Quote:
Originally Posted by Andy_39 View Post
I appreciate the info John! The same here the smell is activated with high humidity, I am in the northeast so right now is 70-80% humidity. In winter it goes away.
I've stuffed insulation in the foundation vents so humid air doesn't come in, I think one of the best things I did, before everything got sweaty.
I left one vent half open for some air circulation and in one vent I installed a foundation vent fan. Its a small fan maybe 6-8" diameter but it fits into the foundation vent opening and has a regular 3 prong plug. You can search on Internet for foundation vent fan, I bought it a while ago so I don't remember the website. It pulls some of the air from crawl to outside. I threw odor eater lava rocks, damp eater things none of those seem to work. My crawl is sealed only entry is thru the floor so no animals can get in/out. Chat soon,
Andy
Wildie is right. To deal with humidity, you need to completely seal all your vents with moisture barrier material. Then, I've been told, you need to add a dehumidifier to further reduce the humidity - and warm the crawl.

If you have any gas or oil burning appliances in your crawl, make sure you have provided them with proper air intake and exhaust before you seal everything up.

On the other hand, if the smell is your only problem, and that vent fan helps, maybe that's all you need during the summer months.

I only need to seal and dehumidify during the humid hot months. I'm probably going to come up with a way to easily seal and unseal my vents. Then, I just need to run the dehumidifier for a few months each year. I need the vents open in colder times so the gas furnace has a supply of combustion air.
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Old 10-19-2011, 01:37 PM   #26
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Bad smell in crawl space.


I'm having essentially the same issue you had described.
I recently installed the cleanspace environment in my crawl space while we had our floors open and we had access.
About 3 weeks after the floors were closed we began getting a noxious smell through the basement and it started travelling up the pipes to other floors.
I can't figure out what it is. I read somewhere else that it might have been either the material the cleanspace is made of or the caulking used to fasten it to the walls of the crawlspace. What were you using to fasten your vapor barrier with?
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Old 10-19-2011, 07:50 PM   #27
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Originally Posted by jamesthoms View Post
I'm having essentially the same issue you had described.
I recently installed the cleanspace environment in my crawl space while we had our floors open and we had access.
About 3 weeks after the floors were closed we began getting a noxious smell through the basement and it started travelling up the pipes to other floors.
I can't figure out what it is. I read somewhere else that it might have been either the material the cleanspace is made of or the caulking used to fasten it to the walls of the crawlspace. What were you using to fasten your vapor barrier with?
The 6 mil Dura-Skrim reinforced polyethylene membrane was fastened to the crawl space walls mechanically, with retarder buttons at 3 foot intervals and sealed all along the wall with Nuflex 110 Butyl Rubber Caulk and Gutter Seal.

The contractor had to wear a very heavy duty air filter mask because of the dangerous fumes from the Nuflex. We didn't notice the smell up in the house and it dissipated fairly quickly down in the crawl.
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Old 10-20-2011, 08:57 AM   #28
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Bad smell in crawl space.


Hey John,

You'll find that you can use a ton of products and sprays to try to get rid of the smell, but they wont actually get rid of them-they only mask them, or cover them up, only to return later on.

If you are serious about getting rid of the odors, we use ozone generators (we are a rental business) and we rent these things out to contractors, car dealers, hotels..tons of different places because they are awesome and work. Ozone is a gas, so you shouldn't be in the same room while it's running, but if you turn one of these units on (depending on how bad the odor is), it'll take care of your problem, just as long as you figured out the source of your odor first.

We've purchased a few ozone generator units from a company called RainbowAir, I think they go by the Ozone Experts now. But here's the website http://www.ozoneexperts.com/

Hope this helps!
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Old 10-20-2011, 11:24 AM   #29
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Bad smell in crawl space.


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Originally Posted by jaydb2783 View Post
Hey John,

You'll find that you can use a ton of products and sprays to try to get rid of the smell, but they wont actually get rid of them-they only mask them, or cover them up, only to return later on.

If you are serious about getting rid of the odors, we use ozone generators (we are a rental business) and we rent these things out to contractors, car dealers, hotels..tons of different places because they are awesome and work. Ozone is a gas, so you shouldn't be in the same room while it's running, but if you turn one of these units on (depending on how bad the odor is), it'll take care of your problem, just as long as you figured out the source of your odor first.

We've purchased a few ozone generator units from a company called RainbowAir, I think they go by the Ozone Experts now. But here's the website http://www.ozoneexperts.com/

Hope this helps!
Thanks for the suggestion.

I've considered ozone, but read that it can have unintended, bad side effects like damaging nearby electrical equipment.

My HVAC gas furnace, indoor coil, blower and filter package, not to mention numerous power, cable, light and phone wires/outlets/boxes are all in or right next to the area that has that smell.
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Old 06-07-2013, 08:55 AM   #30
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Bad smell in crawl space.


Question: Have you or anyone uphill from you, used copper-sulfate to kill roots in or on your/their property or downspout drains?

We did and this symptom immedeatly showed itself.

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