Venting/air exchange/drying underneath a slab?

Old 03-07-22, 07:25 AM
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Venting/air exchange/drying underneath a slab?

The situation is that leaking pipes have deposited water and organic matter underneath a slab causing a severe fly problem in a residence. Is there any way to vent/dry out underneath a slab? Radon mitigation comes to mind, but I've no experience or knowledge with this. Thank you all in advance.

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Old 03-07-22, 01:58 PM
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I think this is going to take someone on-site to address; I don't think we're going to be able to evaluate all the necessary variables remotely. I like the thought process of radon mitigation, as that works by lowering the pressure under the slab so that higher pressure air in the house forces its way into that space and thus the contaminated air never moves into the house to create a health problem. The issue I see is that you need to be able to move air under the entirety of the slab so we would need to know whether the materials under slab allow for air movement.
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Old 03-18-22, 08:23 PM
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The soil under the slab it right up to the concrete. I don't think there is a room for air movement. There is room for the fungus gnat to come out though . Seems like the only way to dry out the soil under the concrete slab is to remove the concrete and the soil. It is about a 25 sq. ft. area that would need to be dug up.
Old 03-22-22, 09:32 AM
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As far as bug killer sprays, you'll want to vacate the house at least until that dries if you spray a lot of it and can't open the windows. I would think that a licensed exterminator would know what's safe to do while you're in the house. You could do some of what they do for cheap but keep in mind that there is no such thing as a 1-time chemical treatment that works forever.

You could buy a 1-gallon jugs of the the interior bug killer spray they sell in home stores and spray that around but don't go nuts with it and poison the air you have to breathe. For my house I typically start from the part of the house I live in and spray the inside perimeter where the floor meets the wall on my main floor. I then go down into the basement and spray the perimeter at the floor and also the top of the basement walls. Bug killer sprays will continue to work for some period of time (3months to 12 months or so) as a surface contact killer so long as you don't wash them off the surface.

You'll want to wear a mask and probably shower after you do that, and then leave the house for a few hours to avoid inhaling all that.

If bug killer doesn't solve your problem, you should get back to trying to seal the cracks. They're getting through somewhere so you just have to find where. After you solve that, your problem will go away--regardless of what's under the concrete.

Old 03-22-22, 07:25 PM
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Thank you for the info, hopefully they will go away at some point.

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