Hi everyone. OK..so although I do like our "new to us" home, the crawl space is an unfinished area....with a sand/dirt/gravel floor. Here's the problem: It has an odor that seems to permeate the house at times...especially now that the AC is not running and neither is the furnace. It does seem to "travel" through the duct work.
I know if we'd cement the floor that probably would fix it. But that's not really in the plans just yet. Any other ideas on how to help eliminate the odor? It's not awful...just would be nicer if it wasn't there at all or even less of it. Kind of an "earthy" smell.
I've heard a few "fixes" but would like to see what you guys recommend. Thanks! As always there's bound to be great ideas from the Hometalk network.
At a min you should install a vapor barrier over the soil. Then you need to look at air sealing and insulation concerns. Ventilation would be the third tier of fixes once the other areas are addressed.
I'll forward this thread to Woodbridge environmental ...this is his area of expertise.
You need to determine the cause of the odor. I would assume that Warren is correct however on it coming up from the ground. However you should seal that floor not simply put gravel over it. You can go the low cost route by simply placing 6 mill plastic over the floor and using caulking seal the plastic onto the foundation walls. Be sure to overlap any seams really well and use a good quality ...»
My bigger concern with this is when you smell the odor. You say you do not smell it when the AC or heat is running, but do so when its not. This does not make any sense to me. Normally when a duct system is located within a crawl space it tends to be poorly installed because of lack of access to the duct seams. This oftentimes results in leakage that pulls the odors into the crawl space. Not the other way around.
Can you take any photos of the crawl and duct system. How is the crawl space insulated? Is the vapor barrier exposed or hidden from view? What shape is the insulation in?
Also for now, be sure your vents are clear again as Warren said, but the best method is to completely seal the crawl space, particularly if the heating system is located in there. supply enough fresh air for the Heat system, unless its heat pump. And bring the system into the building envelope. This will save you lots of money on energy and increase your comfort level within the house.
There was moisture on/into the floor from a leaking pipe from the AC. We did get a sort of "moldy" smell then. Maybe the smell is lingering from untold months/years when the former owner never had that fixed. AND it was stupidly draining into the sump pump instead of where it should have been! ...»
As for ventilation...Gosh I can't remember seeing any foundation air vents! This house does not have a full basement...it's more like a split level arrangement. But of course its 'basement' is still below ground level. I do suspect that all of your are correct in that there's still mold growth down there. As much as I know it's going to be one hell of a job, I suspect we're going to have to remove all the rocks, sand, etc. to see what's really there :-( Running the dehumidifier has helped some.
The crawl space isn't insulated. Neither is the box sill...which we intend to be doing yet this fall. Thankfully this area constitutes a very small portion of the house that's actually not part of the lower level living space. Ya know, when you buy a house and it's already been done, unless you take it apart one never knows what they did under the "finished" look...sad to say.
The house was built in 1961. It sort of amazes me that no previous owner ever seemed to address the crawl space.
BTW, it's rather tall as crawl spaces go. It's not quite 5' tall but that's my height and I only have to bend over slightly to stand up in it. There's plenty of workspace...even the tall repair guy didn't mind it ;-)
I can try to get some pics and put them up. Not sure what I can get with limited light down there. Also, I will copy the info you've all written and we'll use that as our template for a fix :-)
I suspect you've all addressed the best fixes and I thank you sincerely for that!
So glad to have stumbled on Hometalk website!
So you have a split level, from the sound of it you access it from inside the house. So knowing that allows me to understand why you do not have any vents. Most split level homes with crawl/slab type of space does not have them.
You say you have a sump pump? And it does not fill with water when AC is draining into it? ...»
Mildew and odors are the result of mold development of some sort. It is the process of organic materials being dissolved or eaten by the mold. This organic material can be old pieces of wood buried under the surface of the soil when the house was built. It can be roots growing and dying from plants and trees to close to the house. And it can be also damp insulation that is wrapped around ducts, or on the floor area. The material does not have to be in direct contact with water, just in a high humidity level. That is why your dehumidifier is helping. As the moisture is removed, the mold stops growing and eating. The result is the odor goes away. But as soon as it becomes damp again, the odor returns.
This will explain why the odor goes away when the HVAC system works. The AC dries the air resulting in lower moisture levels, thus less smell. And when heat is running the humidity level is lost due to the higher heat and moisture loss due to conventional air flows out of the house. To identify this issue, simply go into the attic where you can, and pull up the insulation above your walls that are located below. Do you see black stains in the insulation? This is the result of chimney effect and the moisture traveling with it as it leaves your house along with your energy bills.
OK, So you now need to figure out what the moisture is having an effect on to create the odors your having. Is the AC duct system wrapped, bare metal, or bare metal lined with insulation?
Is the crawl at all insulated?
Take a gallon size freezer bag and go into the crawl space. Using a small garden tool, dig some soil out of the ground and place it into the baggie. Seal it up and bring it outside. After waiting about five min, open up the bag and sniff it. Does it smell like what your finding in the house? If so, you need to seal your crawl space floor. Ideally plastic with a coating of cement works best. But place gravel down, then plastic then cement. This allows for air movement and water movement under the plastic while allowing for sealing with plastic and prevention of damage with the cement. It also makes for better storage later on.
Another method which we do quite often is we seal the floor and walls using vinyl pool liner material. We purchase this on large rolls of 20 gauge thickness and using lots of ventilation we glue the seams to make the crawl area much like a pool. It is completely water proof below the crawl and is tough enough for those times when access to the HVAC equipment is required. We normally double up the liner where the service person is going to be crawling just to add additional protection from tears. Just be sure to rake any rocks or sharp stones out so no damage occurs to the vinyl.
Lastly, before you insulate the crawl, ask about how to do it properly before you go about it. There are a lot of things you need to understand on how to do this and doing it right will save you money and time. Doing it wrong will only appear to help.
OK..here goes. After I read your post this AM, I went to look more closely at things.
1) there is no insulation in the crawl space...just bare concrete walls.
2) the floor is much drier than it was before...I don't see/feel any moisture in the ...»
3) I've been trying to analyze the odor all dang day! The smell of the crawl space is more or less "normal" for an unfinished basement area...at least to me. What I'm smelling seems to be something else entirely, in the upper level of the home (the main floor level).
So.....after some discussion with my mom, (and she's got a keen nose for smells..haha!) we both came to a couple other possible conclusions.
1) it might be a dead mouse in the duct work somewhere and/or somewhere in the box sill and/or crawl space. BUT...again the odor I'm smelling upstairs is unlike the crawl space itself :-( And heaven help me, but even if it is a dead mouse or something, even that eventually odor would die away eventually...I think(?)
2) possibly the air vent (exhaust..or whatever's the proper name of it) from the kitchen sink might be clogged with leaves or even a squirrel (dead? ugh!)
3) I've checked the floor drain too. It has water in it ...no sewer gas odor there.
The smell is so difficult to describe. It's not really "earthy"...It's sort of a type of "sour" smell but not like sour milk or rotted animal or rotten garlic (OK...don't ask about the garlic...haha!) It's not like anything I've ever smelled in a house before. Not even like the unfinished basements of the historic homes we looked at to buy. They just smelled old.
When I was a kid, we had an old 1916 house with just a crawl space. I don't ever remember a smell like this. My brother has only a crawl space in his 1930's home. They too do not have this type of smell. Right now hubby's got a cold and can't help me figure out this smell at all :-(
So are we on another tangent trying to figure out this mystery odor? Oh please do help, you guys out there.... I'm stymied! And as you know, when one's brain gets fixated on something, it seems it's there even more! Kinda like getting a song in your head and it stays there for days!!! Only this is a smell...and it's real..and not as pleasant as a song in my head.... ;-)
Oh, one last thought: There was some later interior construction done to this house....maybe in the past 5 years or less. I suspect the ductwork may be full of construction dust, etc. Would that have any effect on lingering odors? In our former home, we had the duct work cleaned professionally after we refinished our hardwood floors. Never had any smells associated with the duct work residue but then again, we had them cleaned almost immediately after we completed the floors.
The saga continues....... ;-)
Also, about the AC ductwork in the crawl space...It's all just bare metal....no wrapping or insulation as you asked about. Hmmm....would any moisture cause a sort of "chemical reaction" so to speak with the metal? Wouldn't galvanized metal be sorta immune from producing smells? On the other hand, now that I think of it, our galvanized farm pails could take on an odor at times when we washed them out...till they were completely dry. Am I on to something here...or just pulling at straws?
Are you on a septic system, or city sewer system. Sometimes septic systems can begin to leak at the tank and these are normally close to the house. The result is odors from seepage into the drainage system in the house.
Yes a dead mouse in the house can cause all sorts of odors. We had one in our kitchen stuck ...»
If your saying the odor is at bottom of stairs and perhaps at the top near the kitchen. Have you checked below the fridge? That warm area is a real draw to rodents. And perhaps there is a dead mouse there.
Also check your ac filter area. If it is located at the blower, pull the filter out and using a mirror and bright light, look around at the exposed coil if you can. Does it look really dirty? If so a cleaning is required. This will be really noticeable if your furnace is part of the cooling system. It will smell when you turn on the heat in fall, and smell when you turn on the ac system in the spring. That is a sure sign of a dirty coil and condensate pan located along with the indoor ac coil
Smells can be really difficult to find. So your not crazy at all. I had some homes where I ended up using what is called a SUMA CAN, This device draws air into it where it then goes to a lab to analyze the odors so we can find out what it is that we were looking for. It turned out to be in that case a propane leak. Very tiny but just enough to smell like rotten eggs.
Are you on well or city water? Sometimes if the water table changes sulfur contents can change and water that never had a smell can change quite quickly. Very common in areas that suffer from a drought.
Hang in there, you will figure it out.
-No dead mouse under the frig ;-) We just moved it to paint the wall behind.
-City water/city sewer system. Maybe I should check with the neighbors and see if anyone else has detected an usual smell. We did have an extremely dry summer.
-Just had the furnace and AC professionally checked & cleaned. Should be OK there. New ...»
-Is it possible there's a smell emanating from any ductwork/workings/etc. from a new natural gas water heater we had installed earlier this year...about 8 months ago?
- The smell is not gas smell nor a sulfur smell either. And I'd think if it was a dead rodent (Oh man I hate all rodents!!!) I would think we'd have smelled something really horrible for awhile and then dissipated over time, right :-)
Maybe the drought this summer is causing the lingering odor. I guess that's something I just never thought about since usually basement-y smells to me are associated with too much moisture. Hmmm....you might be on to something there. If that's it, then hopefully the smell will lessen when we begin to turn on the furnace. In the meantime, I'm going to put a big fan in the crawl space and hope to dry out any moisture that may be there.
The dehumidifier was only filling up about every 3 days on continuous running earlier. When we had wet summers, in our other house, I could empty it sometimes twice daily. Of course this is a different house, so not really a true comparison....
Yes, eventually we'll get to the bottom of the offending stink. Again, I sincerely appreciate your expertise. If you ever get to ND, I owe you a really nice dinner at the fanciest restaurant in town. :-)
The odor can be from the backup drainage lines, but again a bit of bleach poured down those ...»
You are correct about rodent smells, they will go away after a week or so. Depends upon size of rodent and conditions it is decaying in. Cold, takes weeks, Inside house, seems like weeks, but only a few days.
If your running a dehumidifier in the crawl, no need to put in fan.
Check the smell on the soil and let me know what you find out. You only need a cup sized amount. So you do not have to dig a lot, But get below any stones on the surface to assure your getting the soil in the bag.
Maybe the odor is coming from the water lines more than anything. We don't use the laundry room sink much either which is just below the area above--the kitchen. And although we do use the ...»
Might I be on to something here? Still, the smell doesn't seem to be a sewer gas type of smell. Ya never know though....Maybe this house is haunted! Haha :-)
My suggestion is to spray bleach on the floor of the crawl space. but be sure that you have plenty of ventilation when doing so. The bleach odors can easily overwhelm you.
I've put baking soda & vinegar down the drains to clean. I'll try spraying bleach on the crawl space floor. We'll see if that takes away the smell. I'm beginning to think the odor is a ...»
I think we've ridden this horse in the race as long as we can :-) Thanks ever so much for all your help! I truly appreciate it.