DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (http://www.diychatroom.com/)
-   General DIY Discussions (http://www.diychatroom.com/f2/)
-   -   Bad smell in crawl space. (http://www.diychatroom.com/f2/bad-smell-crawl-space-76931/)

John_W 07-23-2010 09:03 PM

Bad smell in crawl space.
 
6 Attachment(s)
Need help with a really bad smell in my crawl space.

About a month ago, when the summer heat and humidity first hit us (north Alabama), a corner of our crawl space started to stink of cat urine. I got a good UV flashlight and looked/sniffed every where – over the entire crawl space. I couldn’t find anything – no urine, no poop, no dead animals, and no mold – anywhere down there.

Next, I misted some odor remover (bacteria and enzyme type) on the tarp in that corner. That stopped the urine smell overnight – and it stayed gone.

Unfortunately, a different smell was ready for us the next day. It’s not a mold smell, a urine smell, a poop smell or a dead animal smell. It’s not a chemical smell. I guess it’s a cross between the usual earth smell in the crawl space and something like a weak dead animal smell. But it’s very strong.

I sprayed the tarp again with the odor remover and it just made the smell a little worse. The smell seems to be triggered by moisture since on dry days, it is not as bad. I pulled the tarp out of the crawl space. It stinks a lot, especially when it’s damp. The smell under the house is still strong though, even with the tarp gone.

I pulled one of the batts of insulation out from between the floor joists. When dry, it has a slight odor. After I misted it with the odor remover it started to stink just like the tarp. On the other hand, the empty space between the joists, where that batt used to be, smells good now – just a nice wood smell.

The smell is only present in the south west corner of the crawl, pretty much limited to the area originally covered by the tarp. I put the gray tarp over our radon barrier, in that corner of the crawl, to protect the barrier from damage. That’s a high traffic area – between the door and the HVAC system.

The entire crawl space “floor” is covered by the radon “barrier”. It’s about two years old. The barrier material is white on one side and black on the other, with built-in rip retarding thread. It is bonded to the walls with polyurethane adhesive. All junctions are overlapped by 12” and taped together.

I’ve been blowing the smell out one of the vents with a box fan.

My next step will probably be to pull out all the insulation in that corner of the crawl.

Are there any other options? Is there a better odor removal product – maybe with a fogger that would get into every little crack?

Any ideas about what might have caused this smell?

Thanks.

John_W 07-23-2010 09:08 PM

More pictures.
 
5 Attachment(s)
Here are some more pictures.

Thurman 07-24-2010 09:04 AM

John, this may help you: The photos posted are similar to the underside of my home, but without the HVAC unit and water heater. I have only a high crawl space with a vapor barrier on the dirt floor. BUT: You are in N. Alabama and if I remember correctly you also have red clay soil such as we have here in S.W. GA. I had a similar odor problem just a couple of years after I bought this home, which had sat for sale for two years. We had an addition being done where I work and had a Geologist on site, so I asked if I could hire him to look at my lot. Thankfully he did it for a free home-cooked meal. Looking at my lot, from the street, it slopes from right front corner back to the left rear corner, with an elevation drop of maybe 18"--20". The Geologist told me that water would run through this red clay soil more-so than most other soils. Therefore, water was running through this soil, going through the concrete blocks of my foundation wall, and into the red clay soil under the home, being trapped under the vapor barrier (which was doing it's job) and causing a "musty/moldy" smell. He went under the home, dug a hole maybe 12" deep X 12" in diameter and it filled with water in less than five minutes--not good. He recommended an "Open French Drain" system at the inside perimeter of the foundation, which all led to a brick pit with a sump pump for discharge to the outside. This works--a lot, even in dry weather. The placement of a fan at one of the foundation vents was a big help also. I mounted a squirrel-cage type unit from a split A/C system to the foundation wall, on a timer for twice a day, and this has worked very well. No more musty/moldy odors in the house. David

John_W 07-24-2010 11:54 AM

Quote:

Originally Posted by Thurman (Post 474392)
John, this may help you: The photos posted are similar to the underside of my home, but without the HVAC unit and water heater. I have only a high crawl space with a vapor barrier on the dirt floor. BUT: You are in N. Alabama and if I remember correctly you also have red clay soil such as we have here in S.W. GA. I had a similar odor problem just a couple of years after I bought this home, which had sat for sale for two years. We had an addition being done where I work and had a Geologist on site, so I asked if I could hire him to look at my lot. Thankfully he did it for a free home-cooked meal. Looking at my lot, from the street, it slopes from right front corner back to the left rear corner, with an elevation drop of maybe 18"--20". The Geologist told me that water would run through this red clay soil more-so than most other soils. Therefore, water was running through this soil, going through the concrete blocks of my foundation wall, and into the red clay soil under the home, being trapped under the vapor barrier (which was doing it's job) and causing a "musty/moldy" smell. He went under the home, dug a hole maybe 12" deep X 12" in diameter and it filled with water in less than five minutes--not good. He recommended an "Open French Drain" system at the inside perimeter of the foundation, which all led to a brick pit with a sump pump for discharge to the outside. This works--a lot, even in dry weather. The placement of a fan at one of the foundation vents was a big help also. I mounted a squirrel-cage type unit from a split A/C system to the foundation wall, on a timer for twice a day, and this has worked very well. No more musty/moldy odors in the house. David

David,

Thanks for your comments.

It sounds like you get even more water in the crawl than we used to.

We also have red clay, on a sloping yard (we live on the lower slopes of a mountain) - with a drop of about 3 feet under the house itself - north to south. And we once had water running into the crawl space from under the foundation (in the high NW corner in the picture).

About 15 years ago, we had a general contractor put in a deep french drain parallel to the high (north) side of the house, about 5 feet from the house, and slope the surface dirt strongly to channel rainfall to that same distance from the house. That work, plus a berm installed by the city, uphill from our property, really dried out the crawlspace. When I crawl around down there, I never find any soft spots.

So, I'm pretty sure our current moisture source is mostly the water vapor coming in through the crawl space vents. It's bad enough to cause condensation on the main HVAC supply duct, and sometimes even on the insulation between the floor joists.

In fact, this year, after the first wave of humidity hit us, I found little pools of water on the radon barrier, near the north side vents, but uphill from the HVAC supply duct. It had rained inside the crawl space!

After this odor problem is resolved, I'm thinking of sealing all the vents/gaps in the crawl space walls and using a 70 pint/day dehumidifier down there.

Wildie 07-25-2010 08:35 AM

At my place I had an odour problem in the crawl space that I couldn't figure out.

It turned out that the Transite (concrete) pipe leading to the septic tank had cracked inside the foundation wall.
There is no flex with Transite and settlement of the septic tank broke the pipe at its fulcrum point.
Replacement with ABS ended the problem.

Here in the north, we now seal the crawl space from outside air and make it part of the conditioned air space. Since I sealed mine, its been perfectly dry.

When hot, moist air enters a cooler area, it releases its moisture as it cools. This moisture pools and eventually causes mold growth.

John_W 07-25-2010 12:10 PM

Quote:

Originally Posted by Wildie (Post 474908)
At my place I had an odour problem in the crawl space that I couldn't figure out.

It turned out that the Transite (concrete) pipe leading to the septic tank had cracked inside the foundation wall.
There is no flex with Transite and settlement of the septic tank broke the pipe at its fulcrum point.
Replacement with ABS ended the problem.

Here in the north, we now seal the crawl space from outside air and make it part of the conditioned air space. Since I sealed mine, its been perfectly dry.

When hot, moist air enters a cooler area, it releases its moisture as it cools. This moisture pools and eventually causes mold growth.

Thanks Wildie,

Glad you found the problem.

Do the building codes up there allow sealed crawl spaces? It makes even more sense, down here, but I would be surprised if our codes allow it.

My initial plan is to use a dehumidifier, along with sealing the vents. I don't know if I need to put any conditioned air in the crawl. I have to be careful not to mess up the operation of the radon mitigation system. My radon contractor said that sealed vents plus a dehumidifier would not affect it's performance.

Baby steps.

I'm going under the house now to remove a bunch of smelly fiberglass insulation. :censored:

luvdairish 07-25-2010 12:34 PM

Your crawl looks a lot like mine. However, I don't have all the nice moisture control items (fan, vapor barrier, etc.). Given me some good ideas on how to setup mine! Thanks for sharing!! Best of luck :thumbsup:

Wildie 07-25-2010 04:31 PM

Quote:

Originally Posted by John_W (Post 474986)
Thanks Wildie,

Glad you found the problem.

Do the building codes up there allow sealed crawl spaces? It makes even more sense, down here, but I would be surprised if our codes allow it.

My initial plan is to use a dehumidifier, along with sealing the vents. I don't know if I need to put any conditioned air in the crawl. I have to be careful not to mess up the operation of the radon mitigation system. My radon contractor said that sealed vents plus a dehumidifier would not affect it's performance.

Baby steps.

I'm going under the house now to remove a bunch of smelly fiberglass insulation. :censored:

If our codes don't require a closed crawl space, its certainly recommended by the building department.

I'm not familiar with the use of a radon shield. I would think that there would have to be a method of venting these gases. Do they vent to a roof stack?

Wildie 07-25-2010 07:33 PM

Here's a link to an interesting article about crawl space venting!

http://www.askthebuilder.com/543-Cra...ce-Vents.shtml

Gary in WA 07-25-2010 08:51 PM

http://www.advancedenergy.org/buildi...l%20Spaces.pdf

Check with local B.D. before changing from vented to closed: http://www2.iccsafe.org/cs/committee...E_06_64_07.pdf

Be safe, Gary

John_W 07-25-2010 09:25 PM

2 Attachment(s)
Quote:

Originally Posted by Wildie (Post 475094)
If our codes don't require a closed crawl space, its certainly recommended by the building department.

I'm not familiar with the use of a radon shield. I would think that there would have to be a method of venting these gases. Do they vent to a roof stack?

The pictures show the exhaust stack - inside and outside. The fan is in the box at the bottom of the stack on the outside. Inside the crawl, the PVC from the bottom of the fan attaches to a pipe, under the radon barrier, that runs the length of the crawl. That pipe has holes all along it that pull air from under the radon barrier.

This area has radon coming off uranium in the bedrock. Our house is built on the bedrock, or within a foot of it on all sides. People a few miles away, in the valley or flat lands, who have many feet of red clay under their homes don't have a radon problem.

John_W 07-25-2010 09:28 PM

The inside picture is a before shot
 
The inside picture was taken before the barrier was placed over the pipe and glued to the walls with polyurethane.

John_W 07-25-2010 09:35 PM

Quote:

Originally Posted by GBR in WA (Post 475248)
http://www.advancedenergy.org/buildi...l%20Spaces.pdf

Check with local B.D. before changing from vented to closed: http://www2.iccsafe.org/cs/committee...E_06_64_07.pdf

Be safe, Gary

Thanks Gary.

I don't have foam plastic insulation in the crawl. Are the sections of code in your second .pdf just for foam insulated crawl spaces?

John_W 07-25-2010 09:41 PM

Quote:

Originally Posted by Wildie (Post 475208)
Here's a link to an interesting article about crawl space venting!

http://www.askthebuilder.com/543-Cra...ce-Vents.shtml

Thanks again.

I guess I will check with the local building department before I close the vents.

Wildie 07-25-2010 10:29 PM

Quote:

Originally Posted by John_W (Post 475270)
The inside picture was taken before the barrier was placed over the pipe and glued to the walls with polyurethane.

Thanks for taking the trouble to explain John. Where I live, radon is unheard of, although there are area's within a days drive, where it is a problem.


All times are GMT -5. The time now is 01:51 AM.