Need help setting shower drain in existing slab drain hole!

deedeedeeIY · 05-10-2012, 03:32 PM

I'm planning on installing a DIY-concrete shower base in small master 3/4 bath, it will most likely be 32x32 or 34x34 depending on the boss's final say (wife) and due to size constraints.

House is on slab and there is an existing 1-3/4"ID cast iron drain pipe that is 4-3/4" below slab top and 16 1/2" to center from either wall.

My concern is the 8"x8" hole in the slab around the drain pipe, it is squared underneath the broken 1" thick 6 1/2"x7" slab "top" (have pics will try to post when I get home).

I'm not sure what to do to fill the void so that the new concrete base and drain i'm going to install will not crumble and collapse down into the void, or do I even need to fill the void?

Will the 1" preslope at drain and 1-1/4" base at drain I'm planning be strong enough to support everyday shower use? Base will be stained and sealed not tiled and walls will be tiled over 1/2" CBU.

Previously had a metal shower stall in this spot and we dont want to put a prefab pan in unless we have to, we want to install something that will last and I enjoy the feeling of pride and self worth that comes from making something with my own hands. Not sure if this the right spot to post this or if it should be in another forum but, any help would be greatly appreciated.

TarheelTerp · 05-10-2012, 03:51 PM

Quote:

Originally Posted by deedeedeeIY

...existing 1-3/4"ID cast iron drain pipe that is 4-3/4" below slab top
...8"x8" hole in the slab around the drain pipe...

I'm not sure what to do to fill the void so that the new concrete base and drain i'm going to install will not crumble and collapse down into the void

After you make the plumbing changes required to attach a (2" pipe size) trap and locate the 2" fitting in a spot convenient to align with whatever you end up using for a shower pan... some well packed soil or even sand should be plenty enough base to pour some concrete over.

hth

deedeedeeIY · 05-10-2012, 04:02 PM

the existing iron pipe is 1-3/4" ID and 2-3/8" OD (thick old stuff)...and thanks for the reply.

TarheelTerp · 05-10-2012, 05:36 PM

Quote:

Originally Posted by deedeedeeIY

the existing iron pipe is 1-3/4" ID and 2-3/8" OD (thick old stuff)...and thanks for the reply.

Perhaps I was being too subtle...
There is no such thing as 1 3/4" pipe and even if there were it isn't the 2" required by code (everywhere I know of) for a shower or bath drain. I also didn't specifically describe the trap and vent you'll also need.

iow... the concrete is the least of your issues. hth

**oh'mike** · 05-10-2012, 05:55 PM

You will need to open the concrete and add a modern 2" pvc drain---

Add a clamping drain to hold the membrane--and then fill the excavation with gravel and fresh concrete.

After that--use deck mud to form the preslope--add the membrane--add the Durrock for the walls--pack the base with deck mud---form the curb with fat mud---and you will be ready to tile or otherwise finish the rough base.

deedeedeeIY · 05-10-2012, 09:48 PM

thank you TarheelTerp for the post I appologize for not clarifying in my original post my plans to correct the bad existing plumbing issues, but now I know next time to just ask the question I need answered. More sand to fill in the void is just what I needed Thanks again!

deedeedeeIY · 05-10-2012, 10:01 PM

[quote=oh'mike;918847]and then fill the excavation with gravel and fresh concrete.

So sand around the pipe and drain will not suffice? Will Quikrete 4,000psi be good enough? And yes I had previously found the instructions for the concrete pan and curb here which is why I had planned to do it, I knew it was something that I could tackle, I am still on the fence as to whether I should use the membrane or RedGard on the pre-slope though, plan on it over the CBU.

**oh'mike** · 05-11-2012, 07:38 AM

Use the membrane---Redguard is no up to the task of waterproofing a pan--If you wish to use a surface paint on membrane---look at Latacretes site--Hydroban is the product.

I am building a Hydroan shower today---It's a whole different animal---Look at Latacrete---Mike---

deedeedeeIY · 05-11-2012, 09:18 AM

Thanks Mike, I'll check out the Latacrete site for the hydroban, really appreciate it.

CrAzYDiTz · 05-11-2012, 10:39 AM

You should try a product called the OneLiner, I used it a little while ago for my shower and it was pretty simple to use. It comes with a kit with stuff for both mortar beds too (pre-slope and regular shower floor), drain and a curb kit too. Go to dixsystems.com to see what I am talking about. I definitely recommend it for a diy.