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Cut a board to the wall and prop it straight mount your flange and backfill the water plug hydraulic cement. Within 5 minutes it will turn solid give it a days rest adjust your flange slots off the wall to center and tapcon the puppy to the floor.
 

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Discussion Starter · #3 ·
Cut a board to the wall and prop it straight mount your flange and backfill the water plug hydraulic cement. Within 5 minutes it will turn solid give it a days rest adjust your flange slots off the wall to center and tapcon the puppy to the floor.
Not following you.

How can I cement the pipe into position if I need to have a gap around the pipe for the outside flange?
 

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Discussion Starter · #4 · (Edited)
Cut a board to the wall and prop it straight mount your flange and backfill the water plug hydraulic cement. Within 5 minutes it will turn solid give it a days rest adjust your flange slots off the wall to center and tapcon the puppy to the floor.
I thought of another idea.

Everyone says to back fill the hole with gravel and top off with concrete, minus the gap around the pipe for the flange. If the pipe was perfectly level, that's what I'd do.

Since it's not level, rather than back filling with gravel, I could do your method and fill with Fast Plug below where the gravel would be. I would fill it up enough to where the Fast Plug would be about half way up where the existing concrete slab is. That would give me enough hold to keep the pipe in place.

The remainder of the fill would be with concrete up to the level of the floor minus the gap around the pipe for the flange.

The only downside to this would be the elbow and the majority of the pipe will be encased in Fast Plug rather than gravel. If I ever had to tear it out.....good luck.

Is this what you were suggesting in your top post? Fill the bottom around the elbow, etc with Fast Plug?

 

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Discussion Starter · #6 ·
fill the hole with concrete to the top... dish in around the pipe about 1/2- 3/4 lower...glue hub closet flange inside 4" pipe.. then anchor to concrete...:biggrin2:
Thank you for the response. I only had a couple concerns though.

In order to get the pipe to be perfectly vertical, I obviously have to put some pressure on it to move it over. It's not going to take ALOT of pressure, but enough to 'feel' it. If I concrete the pipe in this position and anchor, any issues with the pipe having this pressure on it for eternity? Is it going to somehow weaken the joint or be more prone to cracking etc?

Also, the pipe is 3" not 4". So I would need to put the flange on the outside. Doubt that makes a difference. I imagine that's why you mentioned to dish around the pipe? But then again, you said to use a flange inside the pipe.

Just so I'm clear, that drawing would work and keep that dished area about 1/2" - 3/4" lower than the level of the concrete?

And as others mentioned, that dish should be about 3/4" thick?

thanks
 

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There won't be enough stress on the pipe to hurt it.
You will want an outside flange when working with a 3" riser. Allow room for the flange hub when you dish the concrete.

Another way is to wrap the outside of the pipe with enough cardboard or sill seal to equal the thickness of the flange hub, pour the concrete, wait for it to cure. Then remove the wrap and glue on the flange.
 
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Discussion Starter · #8 ·
There won't be enough stress on the pipe to hurt it.
You will want an outside flange when working with a 3" riser. Allow room for the flange hub when you dish the concrete.

Another way is to wrap the outside of the pipe with enough cardboard or sill seal to equal the thickness of the flange hub, pour the concrete, wait for it to cure. Then remove the wrap and glue on the flange.
As you can see in the drawing, part of the elbow is exposed. Any issues with concrete around it? Suppose it would just be harder to chisel out if needed...
 
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