Odor and moisture from the crawl space

21 Replies

I had about 2” of water in my flooded crawl space in April. I sucked it out with a utility pump and opened all the crawl space vents. We have not had any heavy rains like we did with the spring thaw and the April showers so there is no more collecting water. However the ground is certainly muddy and it smells like musty dirt which comes up into the house.

I thought I needed a sump pump, but if I had bought one there would be nothing for it to pump out for the past few weeks. I have seen sump pumps that don’t work get locked up so they don’t perform if you do need them. The ground is muddy and musty, but no collecting water.

What I think would be good to cut down on the smell is a crawl space dehumidifier or some kind of fan system. I googled crawl space dehumidifier and they sell some for over $1000.00. Please make a more thrifty recommendation. Thank you.

Have you turned on every faucet and then looked under the house to see if there's a leak? I've seen many times where the bathtub shoe is leaking or the toilet.

Also, check the downspouts to make sure they're far enough from the house and also the grading.

I've seen sump pumps in crawlspaces. You either need to (illegally) discharge the water into the sewer line, or take it way far from the house.

While our climates are a lot different and I've never dealt with a flooded crawlspace. You might look into a gable vent installed under the house. I think you can get one at Home Depot. Instead of pulling heat out of attic, you'll be removing moisture from under house. Just make sure that you have enough air feeding it and you get a good cross draft. If not, you might need more than one. If Home Depot doesn't have one, I know that Grainger sells many different varieties.

Originally posted by Rob K:
Have you turned on every faucet and then looked under the house to see if there's a leak? I've seen many times where the bathtub shoe is leaking or the toilet.

Also, check the downspouts to make sure they're far enough from the house and also the grading.

I've seen sump pumps in crawlspaces. You either need to (illegally) discharge the water into the sewer line, or take it way far from the house.

I actually spent some time under the house while my wife flushed both toilets, ran water in all the drains, etc. to be sure all is well with the drains. It is all fine. This house has a well so I think it just has a high water table. The house sits kind of low to the other houses around it so I think it is a gravity thing.

However, there really is not a flood of water in there now, but it is enough to smell bad. I have found expensive dehumidifiers, but I can’t see why I can’t just use a regular dehumidifier down there. I have also seen crawl space fans. I just do not know what will really work. The so-called encapsulation with plastic seems like it may be a problem if I do get collected water.

How about putting down some vapor barrier plastic? I've seen that done a lot to keep soil dampness down. There is usually enough seems to let any accumulated water drain down if some flooding occurs.

Steve Might Hey Steve I've had this problem with several houses in high water table areas.
I went to BDri a company that specializes with this and they gave me a detailed proposal. If you get me your email or colleague me I'll dig it out and send it to you.
I then had my guys do the work as fill-in between other RE projects.

1. Make sure the grade is pitched away from your house and any old overgrown plants remove or replace any soil that's just humus (leaves that have built up over the years and not been removed, turns into very porous soil)
2. Dig out the basement floor.
3. Install 4" perforated pipe (with a mesh sieve, sleeve), pitched to the lowest point and dig a sump.
4. Replace the basement floor with 6-12" of gravel.
5. Install a vapor barrier.
6. Pour a concrete floor over the entire basement, except for the sump.
7. Pipe the sump away from the house.

Obviously you've got a lot of digging so the final floor is at the same level it is now. And there's usually a boiler/furnace there and electrical wires need to be moved and etc

Crawl space dehumidifier isn't sounding so bad;-)

i did exactly what @Mike Hurney did in one of my homes. i hired somebody though ($5k). it got rid of most of the smell but it hits every once in a while.

i say a dehumdifier is the way to go. try a cheaper one at HD & monitor. if it doesn't work, just return it. no real $ risk for you.

George hit it. Try a vapor barrier first with some gravel on top to hold it down. Then put vents in opposite sides of the exterior walls so you get a cross breeze. That will probably get it at an under $100 fix.

What do you all think of these crawl space fans: http://www.amazon.com/Tjernlund-UnderAire-Crawl-Space-Ventilator/dp/B000N4WOWK/ref=sr_1_1?ie=UTF8&qid=1369976963&sr=8-1&keywords=crawl+space+fan

In our area many homes are built on crawl spaces; we put down gravel and then a vapor barrier; a sump pump pit is dug in the lowest corner of the crawl and the pump placed in the pit and set at a debth to keep the water off the floor. The vapor barrier should help in keeping the moisture off of the floor insulation.
Vents will help with the movement of air and assist with the odor problem. Make sure the discharge pipe of the sump pump moves the water a good distance away from you're crawl space; check the down spouts as well to have storm water directed away from the structure. Many times water enters the crawl from a high water table and not from the exterior. This is a quick inexpensive fix; you could put in perforated pipe, french drain, etc. but I would try this first.

Originally posted by John Moore:
In our area many homes are built on crawl spaces; we put down gravel and then a vapor barrier; a sump pump pit is dug in the lowest corner of the crawl and the pump placed in the pit and set at a debth to keep the water off the floor. The vapor barrier should help in keeping the moisture off of the floor insulation.

Are you digging a trench around the perimeter of the house and laying perforated pipe or are you just letting the water go to the sump pit naturally? If I can skip the trenching process it would save me a lot of time and work.

Also, you put down gravel before the vapor barrier? Don’t the rocks poke holes in it? How thick of a vapor barrier do you use? Thank you all for your solutions.

To update my post we just had three days of rain and I do now have standing water in the crawl, so I will be installing a sump as most of you have already said. The question is if I have to trench out around the house and place pipe or can I just let the water go to the same low corner it always does and put my sump pump there.

Also I need to know about the order of the plastic and the gravel. Most say to lay plastic then rocks on top of that. Do I use 6 mil? Do any of you know about those fans I mentioned above? I appreciate all the help, because this is really the only thng holding me up from renting this house.

How about that Fabreze you see on TV?
In the commercial they spray a dumpster with it, then take blindfolded people into it. They rave how nice it smells. Of course they're disgusted when they remove the blindfolds and see that they're surrounded by (I won't say it;-)

In new construction we do put in a french drain if we able to have it gravity drain. In crawl spaces, we place the vapor barrier on top of the stone; the suggestions we have made are based on economics as it becomes costly to start digging around the property in an existing home, if you can remedy it in a less costly manner. Working in a crawl space is difficullt work (height) in existing homes, I would attempt to get the stone in the crawl at least to the height that the water height has risen (2") and then put in your vapor barrier. When you place your sump pump in the pit make sure you don't attempt to pump out all of the water, only the amount that would enter into the crawl. You want to avoid having your sump pump burning out attempting to pump out all of the ground water that might not enter into your crawl space from the pit. Hope this additonal info helps.

Operate a crawlspace dehumidifier once the space is sealed with the proper ventilation. Even with adequate ventilation, crawlspaces in some areas may still require a dehumidifier.

Mark Forest can you give an update on this property and what solution(s) you implemented? A sealed vapor barrier seemed to do the trick where I have run into this issue, and a sump for persistent leaching issues on a few properties...

Yes, 6 mil with a 12" - 18" or so overlap. Duct tape the seams on properties with persistent leaching.

I would dig a hole about 3' deep and 2' in diameter down there.  Then drill 1/2" holes in the sides of a white plastic bucket - every 2" or so.  Cut other white plastic buckets in half vertically.  Insert enough of the top halves so that the whole assembly is 3' tall.  Wrap the assembly with fiberglass window window screen and duct tape it on.  Set the tall-bucket into the hole and fill around it with stone up to grade.

Buy a small sump pump with a captive vertical on/off switch - not a free-floating or electronic switch - on it.  Right below the check valve on the pump - drill a 1/8" hole.  This will allow the air in the pump to escape as the water rises - and before the switch turns the pump on.  Install a small sump pump into the sump-pit you've created and pipe the discharge in small diameter pipe  (1/2" or 3/4" PVC or PEX)  to a far distance from the house.

Cut a plywood or other material cover for the top of the sump-pit-bucket assembly and lay it over the top.

Then wear a mask while you spread powdered lime down there all over all the dirt.  

Wait a week or so and then spread 6 mil plastic over the dirt floor.  Over lap any joints by a foot or so.  Without this vapor barrier no dehumidifier will ever catch up.

That is as far as I would go before pausing to re-assess in a month or so.  With pumping the ground water down and out - and sealing the dirt floor from the air down there - and ventilating with cross-flow - you will probably be fine.

Are the crawl space vents all around?  On all four walls?  If so I would wait before deciding about installing powered ventilation or a dehumidifier.

stephen
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Originally posted by Mark Forest:

I had about 2” of water in my flooded crawl space in April. I sucked it out with a utility pump and opened all the crawl space vents. We have not had any heavy rains like we did with the spring thaw and the April showers so there is no more collecting water. However the ground is certainly muddy and it smells like musty dirt which comes up into the house.

I thought I needed a sump pump, but if I had bought one there would be nothing for it to pump out for the past few weeks. I have seen sump pumps that don’t work get locked up so they don’t perform if you do need them. The ground is muddy and musty, but no collecting water.

What I think would be good to cut down on the smell is a crawl space dehumidifier or some kind of fan system. I googled crawl space dehumidifier and they sell some for over $1000.00. Please make a more thrifty recommendation. Thank you.

Originally posted by @Chris Martin :
@Steve Might can you give an update on this property and what solution(s) you implemented?

This is a large house and some of the crawl space is separated with walls. To cover all that area in plastic would be too big of a job. I just dug some trenches leading to where the water normally collects and dropped a sump pump into a pit I dug.This job alone took two days.I put both fans and a dehumidifier in there during the summer months.I n fact it is time to get over there again and drop in the dehumidifier.This seemed to stop the pipes from sweating so much and “raining” on to the crawl space floor.

Mark Forest I just saw this post. If you are not happy with the outcome of your fix above you might try and exterior foundation drain since you only have a crawl space (think shallow digging which is fairly cheap). You dig a trench all around the foundation slightly lower then the bottom of the footer. Install filter fabric, drain rock and perforated pipe. Grade this trench to drain to the low corner on the property. At this low point install a sump pump and run the discharge pipe to a point that is lower than your foundation. This will keep your crawl space dry. You can probably get a local contractor to do this fairly cost effectively. Think of how much two days of your time is worth.

Originally posted by @Bill S. :
@Steve Might try and exterior foundation drain since you only have a crawl space (think shallow digging which is fairly cheap).

But will an exterior solution help? The water seems to come up from the ground in the crawl space. I certainly like the idea of digging outside instead of kneeling in a tight dark crawl space, but i wonder if that will work. Thank you for any help.

Mark Forest - Yes it will work. The French drain around the exterior will keep the water table below the foundation and your craw space will be dry. The path of lease resistance for the water will be to your drain pipe and the water will never get above the pipe and drain rock. It must be done right but it's not rocket science either.

My parents house gets standing water after heavy rains. The best way we found to handle this is cross-ventilation. After the rain stops, the dry outside air is the best (and cheapest ) dehumidifier. We installed removable panels on each end of the house that could be opened to allow the wind to blow through.

I had a remodel recently that would shift every time it rained and the new doors would stick. I built up the grade around the perimeter of the house and the problem went away.

If the water is flowing from the yard to the crawlspace then grade may be the issue. If the water is coming up through the ground then that is a different issue.

Good luck and let us know how this turns out.

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