"Tub Box"...Do I need one?

OK, I promise, this will be my last post for the day

So, I am pouring the concrete tomorrow, and I had a question about a tub box. My original plan was to just fill everything with concrete. I have a glued in P trap, so that is pretty much not going to change. The tub shoe is a little below grade but I was going to create a little fixture to keep the concrete away from the shoe and overflow tube.

As I have been looking around this site, I have seen people building boxes and leaving all the area open under the tub. Is that necessary? If everything is glued, including the trap does it serve a purpose?

Here is what my plumbing for the tub looks like:



If building a box is recommended...is the red box large enough, or the blue?

Again, if it is not necessary, I will stick with my plan to create a fixture to just allow enough space so the concrete does not capture the tub shoe or overflow tube. If I do a box I may have to concrete in two steps. One to create the opening, then a second to concrete the floor of the box. Obviously it is easier to concrete everything, without the box. But if there is a compelling reason to build the box, I will do it.

Comments, as always, are greatly appreciated.

Thanks...Mike

Build the red box you will be happy you did.

If I build the box and fill it with gravel will that be sufficient? Or should I have a layer of concrete on the bottom?

I am just concerned about water coming up from the ground...Although I guess I could always keep an eye on it, then put a skim coat of concrete on top of everything (1/2" or so)....

Mike

The tub looks like you flat vented it which is not allowed...The shoe can not be below grade if permanent...the tub will be above grade and it won't work...You will need acccess to the trip waste after the tub is installed in order to install it right and not have a leak...Do you have a ledger board???

Cass said:

The tub looks like you flat vented it which is not allowed...The shoe can not be below grade if permanent...the tub will be above grade and it won't work...You will need acccess to the trip waste after the tub is installed in order to install it right and not have a leak...Do you have a ledger board???

Click to expand...

What is flat venting?

Here is another view of the area:



I still have to install the ledger board. I will do that after I pour the concrete.

Thanks...Mike

The vent apparently is rolled up correctly, but are you sure there is clearance to install the tub? It looks like the vent is in the way.

jimbo said:

The vent apparently is rolled up correctly, but are you sure there is clearance to install the tub? It looks like the vent is in the way.

Click to expand...

Yeah there is clearance. I glued everything in with the tub in place. I will run the ledger board on the long wall. It is a steel tub. I don't think I will need a leger board on the 30" section of tub....I am not sure I could even get one in there with the drain...

Mike

The 2" you used is over kill...what are you going to do when the shoe doesn't fit the tub and it needs to be removed???

The trip waste is normaly installed on the tub after the tub is installed...not B 4

I just noticed you said you had the tub in place when you set the trip waste...good luck, I hope it works out for you because if it doesn't....

Cass said:

I just noticed you said you had the tub in place when you set the trip waste...good luck, I hope it works out for you because if it doesn't....

Click to expand...

So, you called it Cass

It didn't work out. Luckily I did fashion up a sort of tub box, so I can put a new drain in once the tub is installed.

My old P trap was a glue in...Can I use a standard one that is hand threaded, or do I still need a glue in one since it is underground? I may eventually fill in the box with gravel, but it will never be anything permanent. As it stands now, my tub box has a gravel floor (no concrete).

So, if the area is not permanently sealed, can I use a non-glue P trap?

Thanks...Mike

trap

You can use a "non glue" P trap, but why would you want to? If it is done correctly you will NEVER have to take the trap apart until you remodel again.

hj said:

You can use a "non glue" P trap, but why would you want to? If it is done correctly you will NEVER have to take the trap apart until you remodel again.

Click to expand...

Good point. I will go with a glued one. It's less bulky too.

On the one I currently have, I have a 1 1/2" to 2" coupling to go from the drain into the 2" P trap. Now that things are a little tighter and I have to connect everything with the tub in place, is it OK to use a 1 1/2" trap, then use the connector to the 2" drain pipe.

I originally went with a 2" P trap since I figured it was a safer bet. I can get both in there, the 1 1/2 will just be a smidge easier. Is there a benefit to either one?

It is a tub/shower unit, not just a shower. I know if it was a shower only, it would require 2".

TIA...Mike