Smell from Crawl Space

2763 Views 10 Replies 5 Participants Last post by shan1289, Jun 9, 2016

AGould

Discussion Starter · May 7, 2016

Forgive me for being long winded.

This past fall I decided to have my crawl space insulated because there was a persistent musty smell emanating from the space that I wanted to take care of. I had a vapor barrier installed on the floor of the space and the perimeter walls were sprayed with spray foam insulation. The single vent in the space was also covered with foam.

I had some issues with the installation to begin with, including the fact that the foam was only about 1/2'' thick on average. I clearly didn't do sufficient research or vetting because I didn't know the difference between high pressure rigs and froth packs. The guy who insulated my space used a froth pack and denied any wrongdoing when the foam only ended up being 1/2''. He said this would be sufficient to create a vapor barrier and good-enough R-value.

This above issue is frustrating but the more concerning one has to do with an odor in the space. It has lessened to some degree in the six months since the installation, but a faint chemical-like smell remains. I've researched some of the horror stories regarding spray foam, and I can't quite tell whether my issue is related. At this point, the smell may really just be what I should expect of a crawl space, regardless of insulation.

Mine is a split level home, and fortunately the odor does not enter the living space, with the exception of a bedroom that is on the lowest level directly next to the crawl space. There is a large door that is pretty much just the thickness of plywood from the room into the crawl (approx. 3.5'x2/4'). When the bedroom door is closed, the bedroom starts to smell. It doesn't smell exactly like the crawl, but I don't know what else would be creating the odor. It's kind of an earthy, slightly chemically smell. It makes the room essentially unusable, except when the door or window remains open. I'm trying to get the insulator over, although he's been difficult. The foam itself looks alright, for the most part. I don't see sticky places or spots where it is clearly defective. It's closed cell foam that has some mild give when touched.

There are some places on the floor joists where there appears to be some mold. I've treated some of the spots and will treat others that I see. The smell isn't classically "moldy," though, so I wonder whether that's the issue.

This issue is really bothering me, and I'm not sure exactly what to do. I would really appreciate thoughts anyone has. I'm wondering whether I just need to install a thicker, more airtight wooden door into the bedroom, or if I should be trying some other kind of solution? There are no vents to the outside now or into the living space. Is this an issue, considering the smell? I've wondered about air getting "trapped" in the space and having to leave through the crawl door.

Thanks so much for your thoughts.

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Bud9051

· #2 · May 7, 2016

Only half of the job was done and that was done poorly.

Short on time so I just made notes as I read. You answered some but I will post what I noted.....
Installed 6 months ago would put in a cold season and foam should not have been installed at low temperatures.

Foam can have its own smell from off gassing.

Did you cover the foam with a thermal barrier, drywall or special paint? Check your local codes for crawlspace requirements.

Not sure what climate you are in, but ½" is neither a vapor barrier or sufficient insulation.

Once enclosed and sealed from the outside, that space needs to be included into the conditioned house volume with heating, cooling, and air circulation. Good air circulation might accomplish all three but, sending heat down there without good insulation on the walls is a problem, condensation and heat loss.

Did you or he seal the house to foundation plus the rim joist cavities?

You have sealed off that space and should have conditioned it and included it with the house air. If the odor is from the foam that may not work which makes the entire effort a failure.

Bud

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AGould

Discussion Starter · #3 · May 7, 2016

I really appreciate your response, Bud9051.

"Did you cover the foam with a thermal barrier, drywall or special paint? Check your local codes for crawlspace requirements."

I did not cover the foam with anything. Is this something you'd recommend? I'll see if I can find local guidelines.

"Not sure what climate you are in, but ½" is neither a vapor barrier or sufficient insulation."

I'm in the Philadelphia area. Yeah, I'm learning that it's not sufficient, although he's refusing to add any foam, and I'm not excited about the prospect of hiring someone else to add more. Very frustrating, but I'm not sure what to do about it.

"Did you or he seal the house to foundation plus the rim joist cavities?"

Yes, the poured concrete foundation walls and the rim joist cavities were spray foamed, albeit insufficiently, as you say.

"Once enclosed and sealed from the outside, that space needs to be included into the conditioned house volume with heating, cooling, and air circulation. Good air circulation might accomplish all three but, sending heat down there without good insulation on the walls is a problem, condensation and heat loss."

I'm not sure how I'd accomplish this, unfortunately. Our central our ducting is in our attic only, and we have baseboard, oil-fueled heating, and I imagine it would be a huge project to heat that space. Is there another way to accomplish air circulation without opening of the vent to the outside again? Worst case scenario, I could do that, although it would obviously make the insulation down less useful than it even already is. Can I assume a one-time, days long ventilation out a window with a powerful fan would be unlikely to help in the long term?

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Bud9051

· #4 · May 7, 2016

You probably didn't think about it, but whenever you hire someone to come work on your property, request a certificate of insurance from them. It comes directly from their insurance company and tells you what coverage they have and gives you the company to call if you have a claim. Like, if all of that foam is off gassing and has to be removed.

If they don't want to or cannot provide one then they have no insurance.

Philly would be climate zone 4 with a minimum of r-10 if a continuous cover, no studs. That's from the 2009 energy codes. They may have moved to 2012 but I think they are the same. https://energycode.pnl.gov/EnergyCodeReqs/?state=Pennsylvania

The two choices for a crawlspace are to either cover the floor and seal and insulate the walls, or seal and insulate the ceiling above the crawlspace and then ventilate the space. But in either case, that air needs to be exchanged, either with conditioned air or outside air.

In most cases homes in cold country will seal off the crawlspace and insulate it, the direction you started.

Check local codes to see what is required for covering the foam if anything. Rules for crawlspaces can vary. In a basement it must be covered. The choices for covering it are framing and drywall or an expensive intumescent paint sprayed over it. The paint is probably your only option, but first the r-value issue needs to be resolved. That would require another inch of foam, but it should also require everyone to move out for some time. Check the foam mfgs guidelines.

A window open for a day would not be a long term solution. If you are already seeing mold down there in 6 months, you need to ventilate that space. If humidity is not too high you might consider ventilating it to the outside during the summer. But warm humid air can cause condensation in a cool crawlspace so a tough choice.

Bud

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AGould

Discussion Starter · #5 · May 7, 2016

Many thanks, again, Bud. It's helpful to have the energy codes, so I can show them to the insulator and to consumer protection, if needed. The guy also didn't tape the vapor barrier at the edges, and I'm pretty sure he didn't ventilate the space while spraying, which I gather is recommended. Totally awful. He at least had us out of the house for a couple of days.

I'll definitely be checking insurance in the future. I spoke to someone who said that foam removal would not be covered, though, unfortunately. I'd really like it to not come to that, of course. I wish there was a clear way to test for the foam's safety and level of off gassing. As for the mold, I think it was present prior to the insulation being installed, I just didn't do a thorough look after I removed batt insulation that was installed on a portion of the ceiling.

I didn't realize the foam needed to be covered by something. I'll have to look into it.

This is my first time posting here or any where like this, and I'm grateful for your thoughtful responses. This issue has caused me a ton of stress, and I'm eager to have it resolved.

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Bud9051

· #6 · May 7, 2016

Although I'm a contributor here along with many others, I started visiting the forums when I needed some advice. I sure wish I had something like this available 40 years ago. You will find different personalities and contributors who are skilled in different fields, but as a home owner, DIY forums should become a regular source of information. And I expect all forms of internet help to explode over the coming years.

Off my soap box. I have read some threads from home owners in Alaska where they ventilate their crawlspaces and basements by exhausting air to the outside. This might be a solution for you. Since your crawlspace is well sealed, if you install a small exhaust fan (think something like a radon fan) and run it 24/7 venting to the outside, the replacement air will have to come from the house down through the many leaks. Radon fans are designed to run continuously and use maybe $20 a year in electricity (size dependent). This would take the chemicals or whatever is generating the smell and dump Them outside.

Best,
Bud

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Nik333

· #7 · May 7, 2016

Bud9051 said:
In most cases homes in cold country will seal off the crawlspace and insulate it, the direction you started.

Sorry for my ignorance, but insulation really interests me, lately. If cold air falls, how does the crawlspace affect the house above? By conduction?

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Bud9051

· #8 · May 7, 2016

Hi Nik,
Heat exchange between the house and basement includes the 3 primary transfer mechanisms, conduction, convection, and radiation. Stack effect in the winter is simply convection of outside air (colder and heavier) leaking into the lower spaces and forcing the warmer air inside up and out, that is why air sealing is so important. Once sealed, there will still be some leakage but minimal.

Heat will still move through the floor structure and warm the air below as well as the warm floor above will radiate energy into the crawlspace. If the insulation on the foundation walls is sufficient it will remain comfortable down there. The problem the op is having is an odor from somewhere which is making its way into their living space, thus the need to get some air exchange going. Actually, some air exchange is needed with or without a problem odor.

Bud

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Yodaman

· #9 · May 8, 2016 (Edited)

INMO, sealing off the space is a mistake. It needs more ventilation not less.

You just made it thru the most forgiving 6 months of the year regarding mold season, which is the winter heating season,
The next 6 months will be less forgiving and you may turn your crawl into a science project.

Does it really make sense to seal, insulate, heat and cool a crawl space when all it really needs is ventilation?

I would insulate and air seal under the first living floor and provide ample ventilation to the space.

You can buy crawl vents that auto close in cold temps and open in warm temps.

just my OP, no disrespect to Bud,

http://www.thisoldhouse.com/toh/asktoh/question/0,,20577860,00.html

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Bud9051

· #10 · May 8, 2016

Hi Yardman, with the many sources of information flooding the internet, different opinion are to be expected.
I just took a quick look at that link, LOL, he has it backwards. Quote:
"These vents allow outside air to circulate under the floor in summer to prevent the moisture buildup that encourages mildew and rot." Moist summer air circulating into a cool crawlspace is a source of moisture.

"In winter, when the air is drier, the vents are closed to reduce the chance that the pipes in the crawl space might freeze." That drier air is needed in many crawlspaces to keep them dry.

One of the big differences in the advice one should follow is based upon the location. Philly is kind of inbetween, but still can benefit from an enclosed crawlspace if it is properly insulated. Been awhile since I read this link but it should cover this topic better than my memory.
http://www.greenbuildingadvisor.com/blogs/dept/musings/building-unvented-crawl-space

Bud

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shan1289

· #11 · Jun 9, 2016

In some cases, crawlspaces absolutely do not need ventilation. Here in North Carolina, that actually causes damp air to get trapped in crawlspaces, which increases humidity in houses, and is why central North Carolina is a hotspot for crawslspace research (yes, there actually is such a thing) and why many people here elect to seal the crawlspace to help control humidity.

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