We have a new house in the Northern Midwest, and underneath a bathtup in the basement a 15 inch square hole has been punched into the slab to allow the drain to exist. I've learned this is a Dap Out. It is currently exposed earth, and the nearest outside wall to this hole is at least 10 feet away. I understand filling this with concrete makes it difficult to service the PVC drain pipes, should they become clogged. One inspector recommended filling it with spray foam, thinking you could at least dig through that if needed.
My questions:
- Is it acceptable code to leave the earth exposed?
(inspector in Wisconsin said he sees this all the time. Builder in Illinois thought it was crazy not to pour/seal a proper box)
- what about Radon, or water, insects, animal intrusion?
- it seems this builder added the tub late in the building process, so it was not planned, hence, the hole was punched out and not really finished off.
Thanks! - Plumbcrazy

I would foam over the dirt, but not fill the rest to make it easy to service.

Massplumber, There's already a bathtub installed in the basement. Crazy's asking about the dap-out.
Crazy,We leave our dap-outs open in my area unless we are ordered to seal it. In that case we hit on the roofers for some melted tar and pour it in the hole just enough to cover the bottom of the hole. Regards, Tom

This is a weird one for me because I do not see MASS has written anything. He must have picked up invisible plumbing skills. At least his ghost is here because Tom got a greenie from him.

YUP! Ballenger... I deleted my post because I misread the post... my answer was just plain silly once Tom pointed out that I missed something. Have a good day!

OH! And hey, I borrowed and posted a link of yours on HOW TO BUILD A SHOWERPAN.. hope that is not a problem... great link... and knew it would really help this guy out. I did tell him where I got it.. just in case he contacts you... :)

Take care.

I just used that link 2 seconds ago, its not my property so use it when you want. That guy is better than me so why try to improve on perefction. I did not know you could elete your post 100% completely.

Thanks.. it is a great link.

And yes, can delete entire post by pressing edit.. then delete.. then must answer why deleting answer, and then press delete.

I have used this feature twice... each time it was because I read asker's post too quickly... I can get excited sometimes ;) Bye for now.

Thanks guys for answering me. (exposed dap out box under basement tub)

It seems like this practice of raw (exposed earth) dap out "boxes" could increase Radon entry, and possibly gets a higher reading on a Radon Specialist's metering. I know half of the population think Radon is not worth worrying about, unless code requires it.

It just seems a raw hole in the floor with some gravel or foam sprayed on seems rather crude compared to all the engineering that goes into slab pouring, expansion joints, drain tile and sump system and an otherwise robust effort at sealing the house from outside intrusion, be it animal, gas, water or anything else that likes to burrow and pop it's head through our lovely planet Earth.
Am I really being crazy here? (Plumbcrazy2, my orig. sign in was not working)

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Am I really being crazy here?

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No! I don't think you're crazy. Just cautious.
I've never see it done but if it really bothers you you could dig the dirt down below the trap and build a box/form around the sides and fill the form and floor with cement. That way the trap and tub waste could be serviced and your worries would be over. Regards, Tom

Here is an in between answer to filling with cement. You can buy a 20 lbs bag of 20 minute drywall compunds for $7. Mix it and fill your hole, if you ever need to get back into that area it will chip out with hand tools but seal as well as cement. If you get Radon it will find somewhere else to get in. Buddy of mine is doing just radon work now and he's raking in the money.

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Originally Posted by ballengerb1

Here is an in between answer to filling with cement. You can buy a 20 lbs bag of 20 minute drywall compunds for $7. Mix it and fill your hole, if you ever need to get back into that area it will chip out with hand tools but seal as well as cement. If you get Radon it will find somewhere eles to get in. Buddy of mine is doing just radon work now and he's raking in the money.

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That's a neat idea, so is digging further down... this space is hard to get to, so it'll be foam or drywall compound most likely. Thanks, I'll let you know what the Radon police think. Plumbcrazy2

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Originally Posted by ballengerb1

Here is an in between answer to filling with cement. You can buy a 20 lbs bag of 20 minute drywall compunds for $7. Mix it and fill your hole, if you ever need to get back into that area it will chip out with hand tools but seal as well as cement. If you get Radon it will find somewhere eles to get in. Buddy of mine is doing just radon work now and he's raking in the money.

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Don't do this. :eek: I ran this idea by our inspector and he says: "The comment about using drywall compound does not make sense to me. Putting an organic/food source for mold on top of earth is just asking for a mold problem.":eek: I have to agree, while I admire the creativity, I opened up an old tub of drywall compound and it's covered with mold. I think his original idea about expanding foam will work, it's not a mold food source, will fill the hole, and you can carve it out if you need to get at the pipe. (I'm still wondering what the official RADON EXPERT solution is. Seems like a backdoor for radon that nobody is talking about. Thanks for your answers!

Hey Plumb...

Just wanted you to know that Ballenger was not talking about joint compound in a bucket... that certainly would be a breeding ground for mold... *yuck*

He said "20lb bag of 20 minute drywall compound"... See, that is a dry mix that when mixed with water creates an exothermic reaction that sets off the compound mixture to cure very quickly. That is the key here... cure time.

Compound in a bucket will almost never cure if set down too thick or on moist ground... it is like setting it back in the bucket. They design it that way so it can sit on shelves for damn near a lifetime!

20 minute dry mix compound on the other hand is meant to set off no matter how thick... all about chemical reactions here. This compound dries hard and becomes brittle... why it breaks out so nicely!

Anyway, I am sure you would be fine with the 20 minute compound, but if foam is what you decide I am sure that will work fine, too.

Hope that helped.

Thanks MASS, yep the key is to use 20 or 45 minute mud. Redi-mix in a bucket would be like a buffet for mold. Even though the building inspector was not hot on the idea I'll bet he had no official voice to refuse to OK it.

Weather Foam or Drywall mud, I would duct tape around pipes, so when it has to be removed(foam or mud) then when the tape is unwrapped, it will be clean?

Yep, nice idea. That or a good rub down with plumbers grease.

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Originally Posted by massplumber2008

Hey Plumb....

Just wanted you to know that Ballenger was not talking about joint compound in a bucket....that certainly would be a breeding ground for mold...*yuck*

He said "20lb bag of 20 minute drywall compound"...

Hope that helped.

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Great clarification. I'll let the inspector know the difference. The tape or grease on the pipes is nice too. Thanks! Plumbcrazy2

When I do Satellite or coax connections, I tape over, then Silicone, This way when I have to expose, threads are clear.