Shower replacement, 1.5" to 2" conversion - do I need to replace vent pipe too?

[DaveG_NJ]

Hi there. I am replacing a second-floor standing shower and have ripped out the old tile and backer board down to the studs and subfloor. I removed the old (1960's) drain -- a cast-iron affair with integrated trap (full of sludge) and I have 1.5" copper pipe to the T and down to the basement drain and up to the roof vent. I think it best to go 2" down to the basement and have a few questions...

1) What is the technique for removing the old copper pipe from the hidden 1 floor drop? Do I cut in the basement and cut sections in the shower and pull up, maybe a few feet at a time, cut and repeat?

2) How does one insert the new continuous pipe? I figure it's about a 12' length.

3) Do I need to replace the 1.5" vent pipe with 2" or can I leave it as it just a vent and no water would flow through it?

Apologies for the nasty photos - there was rampant leakage in the old shower (bad tile job) and under the liner was a moldy wet mess. The weep holes in the drain were mortared over and the water had nowhere to go.

Thanks!

 

[Terry]

The shower or tub can use a 1.5" vent.
New code calls for 2" for the shower or tub waste. A 1.5" trap is fine for a tub, and 2.0" for the shower.
In Canada, I believe it's still okay to use 1.5" for the shower. Frankly, with shower heads restricted to 2.5 gallons, it hardly matters.
If you replace the waste side to 2", you may need to open up some walls below. Often the 1.5" copper will go into a 2" cast iron hub.

 

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[Jadnashua]

Sounds like you've done some research, but be forewarned, one industry study showed that approximately 75% of showers were not constructed to industry standards! There are lots of ways to do one that works, but it is very detail oriented, and failing one aspect can doom the thing to eventual failure. Once you get the plumbing sorted, I suggest you check out www.johnbridge.com for help building up your shower. I've put a few threads in the Tutorial section in this forum, but there are a huge number of professional, qualified, tile guys over there verses here. The type of drain you end up with can vary, depending on the technique you choose for your pan and shower construction.

My personal preference to a modern shower is a surface applied, bonded waterproofing...done right, everything beneath the tile is 100% waterproof, not just water resistant, and the whole thing dries out MUCH faster (a conventional shower's pan never does, but it should not be holding liquid, only be damp). More than one company makes materials to achieve that.