New house, several crawlspace issues. Need help.

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  #1  
Old 06-29-14, 10:38 AM
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Exclamation New house, several crawlspace issues. Need help.

My wife and I just purchased our first home and on the whole it's nearly problem free. However, the crawlspace has a few issues that need addressing so they don't become bigger problems. It currently has too high of a humidity/moisture level, a significant camel cricket infestation, and open/exposed ventilation gaps. I'm looking to troubleshoot all three of these issues myself as best as I can, but could really use some advice as I have absolutely no experience in this sort of thing and am essentially just going in to it blindly.

#1. Humidity/ventilation. The home inspector only noted one area where moisture entry may be a problem. The entire property is a gradual slope (front yard higher, back yard lower) and the two crawlspace vents at the front of the house are right at ground level where water can easily trickle in. I've purchased (and will soon be installing) a vent well to help mitigate this. However, I'm not convinced that will solve the high humidity. What are some other relatively inexpensive ways to mitigate the moisture level? Should I look into buying a crawlspace fan (like this? Tjernlund UnderAire Crawl Space Ventilator - Deluxe Two-Fan, 220 CFM, Model# V2D: Electric Household Fans: Amazon.com: Industrial & Scientific) or is there another method I should look into?

#2: Open/exposed ventilation gaps. Here is a picture of what style the crawlspace vents are: PHOTO_20140629_113404.jpg - Send Files Online - TempSend.com What is the best way to screen these off without too much hindering the ventilation/airflow? Is there an easy way to just simply attach screens to these? Would I do so from the inside or outside, and what's the best way of attaching them? Or is there another option I should look into?

#3: Camel cricket infestation (yuck). I'm glad to know these guys are mostly harmless, but they're still a nuisance and just in the few days since we've moved in it seems like they're growing in numbers. It seems logical to me that I need to first block as many entry points as possible (such as the open vents) and do some sort of perimeter treatment (recommended products?) first, and then work on baiting and exterminating the contained population inside the crawlspace. Does that sound like the right plan, and are there any other tips somebody with more experience might have? Any recommended products or brands?

Would really, really appreciate any advice or help here. Also new to the forum being a first time homeowner, but plan to be around on a semi-regular basis and maybe eventually I can start to help others as well. Thank you!

Edit: Forgot to add, natural pest solutions are preferred, but only if effective.
 

Last edited by waltherj; 06-29-14 at 10:56 AM.
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  #2  
Old 06-29-14, 02:10 PM
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Is there a vapor retarder , (at least 6 mil polyethylene) over bare ground or do you have a concrete slab, hopefully with poly under it ?
 
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Old 06-29-14, 04:11 PM
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Hi walther and welcome to the forum.
First some basics.
You can go with a vented crawlspace or a closed and conditioned space. If vented, the vents get closed in summer and opened in winter to avoid humid air entering a cool space and causing moisture problems. However, it you have cold winters, then open vents will need to be accompanied by fully insulating the floor above. That still leaves the issue of closed vents in summer where the humidity down there will have no way to escape.

My preference is to close vents permanently and insulate the walls, along with the vapor barrier calvert mentioned. I'll attach a link for reading and photo 5 is a great example of how a crawlspace should look.

BSI-009: New Light In Crawlspaces — Building Science Information

Bud
 
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Old 06-29-14, 05:36 PM
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That's a pretty intense article. I read through some of it, but obviously some of it is over my head. Here's some more information that may help:

The crawlspace is just dirt with a vapor barrier (which was only installed very recently, there was no barrier before that). As far as the vents go (as in the picture I provided), there are only two on each side of the house, two in the front (one is a different style though), and none in the back. I don't think the floor of the house is insulated at all, nor the walls of the crawlspace (it is concrete/masonry I believe).

Since these vents don't have the ability to open/close, what's the best solution? Or conversely, I am interested in the idea of a closed crawlspace (would be easier to keep pests out), but how would I then keep the moisture down? And how important is it to insulate the floor? Is that crucial or optional?

Thank you!
 
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Old 06-29-14, 05:53 PM
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TN is probably not too cold, so 1" of rigid foam board on all the walls down to the plastic and sealed to same. If the plastic is well sealed there should be little to no moisture down there. By adding a dehumidifier or if you air condition upstairs, sharing some of that air with the crawlspace.

The rim joist that rests on the foundation also needs to be sealed and insulated. What is the height of that crawl, floor to joists above?

And, what is your climate, cold or coastal?

Bud
 
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Old 06-30-14, 08:17 AM
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The ground is sloped/uneven, so at the front of the house the crawlspace is probably only a few feet in height, but by the time you're at the back of the house it's easily standing room (basically like a cellar).

Climate here is warm (80's-90's) and very humid in the summer, but it can get relatively cold in the winter. We usually get nighttime lows below freezing for at least a portion of the winter months, and the occasional light snow. This last Winter we dropped into single digit a couple times, but that was unusually cold.

If I were to do the foam board around the walls of the crawlspace, what's the best way of attaching/installing it?
 
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Old 06-30-14, 09:28 AM
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There are many adhesives that will work with foam board. If you are going with just foam board with no fire barrier like drywall, typical for a crawlspace, then upgrading to one of the better foil faced foam boards will give you a fire barrier all-in-one. Dow Foamular 250 I believe is one, but check local code requirements as they vary.

For an adhesive I have been using for most projects the Loctite PL 3X. Cures rather quickly and works everywhere. If you have a lot to do, invest in the contractor size applicator, if you can get the adhesive in that size.

Bud
 
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Old 06-30-14, 12:19 PM
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Sorry for all my questions, I really know nothing about this stuff at all. I appreciate the advice a lot. So just to make sure I understand correctly, you're suggesting I apply foil faced foam boards to all the crawlspace walls (but still leave the vents open?), and this will insulate my crawlspace better and significantly lower the amount of moisture? Then all I need to do is just get some kind of screen material over the vent gaps, or should I still also invest in vents that I can open/close depending on the season?
 
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Old 06-30-14, 12:33 PM
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Going with the sealed and conditioned crawlspace means closing off those vents and leaving them closed. Along with that you will need to share that space, now nice and clean, with the conditioning of the house. If you have forced hot air, then a small supply and return. If not, then a small dehumidifier to maintain a lower humidity. It should not run a lot being well sealed from the soil. You can monitor the RH and decide what is needed later.

Be sure to bring the floor plastic up the foam board a foot or so and tape it for a good seal.

Bud
 
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