Toilet in Slab - Closet Flange Type/Size

[wd414]

Hey All,

I'm installing the drains for my house's concrete slab. Thus far I have a 3" pipe feeding to the toilet. I have also purchased a toilet flange that is a 3x4. My understanding is that this closet flange fits inside of a 4" pvc pipe or the outside of a 3" pvc pipe. In thinking of the order of operations for the actual installation of the closet flange it seems that it would be easier to have a 4" pipe coming up through the concrete. Then, after the slab is poured, and when we're ready to install the toilet, I can cut the 4" pipe flush to the finished floor height and then glue/insert the closet flange inside of the 4" pipe.

If I am thinking of this correctly, that seems a whole lot better than putting some foam around the pipe prior to the pour. Then, after the pour, measuring down from the finished floor to account for the height of the closet flange fitting.

What fitting should I use to use the 4", flushcut method?

Atch't images show drain layout and current state of pipes.

Thanks all!

 

[Breplum]

We absolutely recommend a licensed plumber review (or of course, better do the work) your work. there is so much to know and because the work can never be redone, you are best off hiring a pro at least for the underslab. We have seen countless failed underslab plumbing jobs done by Di’y. Just properly supporting the piping is critical and prone to failure, not to mention a million other points of failure.

 

[Sponsor]

 

[wd414]

Hey Breplum - I whole heartedly agree. In a previous life I held a Journeyman Electrical License and know very well the complexities of the NFPA, IBC, IPC etc and the knowledge required to accurately build a compliant system. I probably should have mentioned that the photo with the PVC was very early stages of layout and is in no way intend to depict the final product. There are many stages of work for this apprentice plumber to complete. I do have a Master Plumber consulting on the project. However, I really like to take options to him and work to select the best fit. So, in this case, I am looking for alternative solutions to the 3" pipe stubbed up and later fitted with the closet flange.