Replacing CI main line with PVC - need advice

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Vladr

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Good morning!

Been following terrylove.com for ages, but this is my first post, since I'm in a bit of a pickle and the clock is ticking...

Some background:

I'm having someone dig up the old rat slab in our 1920 2-storey home's basement early next week, and then pour a new 4" slab a few inches lower.

In the process, I wanted to redo the building drain, for two reasons:
  1. original 20's cast iron, not in great shape underground; now would be the time to replace w/ PVC;
  2. the current drain's run is too long and shallow to fit as-is under the new slab (needs a 6" rise); want to reroute it so it travels a shorter distance under the new slab, then goes up near a wall with a riser, then connects to the (supported) main stack above-ground (see pics).

I also wanted to add a branch drain for a basement bathroom while the ground is open.

Unfortunately, the plumber who I had slated to do all of this is no longer available, and his potential replacements say they're booked for at least one month or won't even call back.

Long story short, I'm likely stuck doing this myself, and would like to run the plans by someone more knowledgeable.




For now, I have anchored a pair of 600lb brackets into the foundation walls and supported the bottom of the existing stack w/ a riser clamp (see pics). The stack is also clamped at the top of the 2nd floor and strapped to the structure at the bottom of the 1st floor.

  • Am planning to cut the CI below the raiser clamp (B), and transition to PVC (C) using something like the Fernco P3000-44.
  • Combination wyes w/ cleanout access at or near every change of direction (D, E); horizontals pitched 2%.
  • Tying into a 4" horizontal double-wye (H) which takes in the output of both the main line and newly added branch, and also provides building sewer cleanout access (G) per CMR 10.08(g)(1).
    [[The reason for the double-wye (as opposed to, say, two wyes in-line) is to be able to keep both the cleanout (G) and branch backwater valve (K) accessible within 2'-3' of the foundation wall (rest of the basement will be finished and floor covered). I'll have to be extra careful with ensuring the correct pitch for the main line and branch.]]
  • On the newly added branch drain side, proposing to add a normally-closed 4" backwater valve (K) then transition to 3" w/ a wet-vented bathroom (2" for the vent and lav, 1.5" for the bathtub, 3" w/ a 3x4 hub x spigot closet 90 and inside-fit flange).

Anything wrong with the proposed layout or plan? I'm in MA.

Thanks!
 

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wwhitney

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So maybe turn the lav/tub branch from hitting the WC fixture drain at a 22.5 to hitting it at a 45, and then enlarge the lav drain to 3", with a 3" cleanout on the vertical lav drain just above the floor.

On the cleanout just before the building sewer, any reason it couldn't be on the main 3" line coming from upstairs? In which case you should be able to eliminate the double wye.

Cheers, Wayne
 

Jeff H Young

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Code on the cleanout in my jurisdiction would be issue as the w/c is over 5 foot off the line served with cleanout if you used a wye without adding the 22.5 fitting it should fly, then again Mass isn't UPC right ? so not sure
 

Vladr

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Thanks for all the feedback! I'll add the lav cleanout, and a 3" cleanout for the toilet.
On the cleanout just before the building sewer, any reason it couldn't be on the main 3" line coming from upstairs? In which case you should be able to eliminate the double wye.
Code here (MA) says it has to be "so located as to provide accessibility in direct line through the building drain to building sewer." (CMR 10.08(g)(1)), so I'm not sure if the extra 45 would fly.
 
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