Basement Bathtub Support

brockmiera

I'm getting ready to demo a sloped concrete shower base in the basement to replace the p trap. The little lady wants a bathtub down there instead of a shower stall. Now I need to demo a little more in order to put the right drain assembly in for a tub vs a stand alone shower.

My question is this, do I need to pour concrete back down and make a level pad in order to support the tub or would a nailing flange (2x4) and concrete on the outer edges be enough support?

Here is a picture of what is there now.

Thanks in advance for your help.

Attached Thumbnails

 

brockmiera

Another question;

I've see a lot of posts talk about an access hole to get to the trap below the tub. something like 13" x 13" or so. Now in a basement is that typically left open? is if filled with gravel? Wont bugs and critter and what not get up into the house that way?

tylernt

Cast iron tubs only need support around the perimeter.

Fiberglass and acrylic tubs generally require support under them in the middle (by throwing down a layer of wet mortar, then setting the tub into it).

Steel tubs... a quick search found one guy that said support underneath is not needed, however I personally would at least add a bed of expanding foam or something to avoid that "hollow" sound as well as hold the heat in when bathing.

brockmiera

Yeah that is kind of what I was thinking. I like all the ideas of cast iron except having to carry it downstairs!!!

joecaption

Totaly depends on the tub.
Find the tub your thinking of installing and go on line and check the install info.
Some of the newer acrillic tubs come with an attached foam block to support it.

brockmiera

Hey that isn't a bad idea. Sometimes the obvious answers escape us!

On a side note, I did some searching and found the term Dap Out which refers to that 13"x13" pit used to access the trap for the tub.

I dont want to leave exposed earth.

Have you or anyone heard of digging the hole a little deeper, forming a couple inches of concrete in the bottom of the hole and then setting a 13" x 13" box form on top of it once it cures? Then I can pour concrete down the walls between the form and the earth to create a fully encapsulated Dap out Box.

TheEplumber

I've done similar for radon gas- needed an air tight slab. In your case, I'd hook up the piping, test for leaks, fill the hole with sand or pea gravel and top the top 1" or so with concrete.

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brockmiera

I suppose thats one way. what about still doing the dap out but have the bottom and sides tie into the slab?

Am I making it harder than I should be?

tylernt

I can't imagine insects or animals burrowing deep and far enough to be a problem, but I suppose radon might potentially be an issue. I wouldn't worry about it personally, but it's your project so do it the way you want.

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TheEplumber

Yes your over thinking it....

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brockmiera

Stupid Brain!!! Ok thanks I'll get on it and just fill in with gravel. Cap it with an easy to remove layer of concrete.