[jyl]

Okay, I cut the old subfloor out. So now from joist to adjacent floor I have about 2” of height to play with. I’ll shim the joist tops and screw down 3/4” OSB. Some dry rot to fix.

Zeke, I am not sure about the floor drain details. I hired a commercial plumber and it’s his job to get them right. On the first floor, we have five floor sinks draining to a grease interceptor in the basement garage, everything in the kitchen and coffee bar drains to one of those floor sinks. The mop sink and handwash sink do not (if I recall correctly). A floor drain in the kitchen. The bathroom sink and toilet which do not go to the interceptor of course. Basement has a full bathroom and a laundry sink. Second floor has a kitchenette and a bathroom with shower. The plumber has been doing DFU calculations. The building has a 6” sewer line and the waste pipes I see going in seem pretty hefty. All the original plumbing is being removed, a full repipe. It will be new Pex and black plastic throughout, with copper stubouts.

The floor sinks are a hassle. The first floor is only 2x8 and the basement ceiling is low, so the standard floor sinks we got would have had people in the basement hitting their head on P traps. I had to order shallow stainless steel floor sinks, $1,700 worth, and waiting for them to arrive is holding up the work.

In general there is a lot of figuring out how to fit all this plumbing into the building.

The venting is a challenge, since all the existing vents are too small, and there are too few of them. We will be getting a roofer out to flash the new vents. In one case the old wall studs are too skinny for a horizontal vent run and I had to frame out a second 2x4 wall just for the venting.

The latest issue is the mop sink is right above the gas water heater and it’s exhaust duct to the chimney, I guess plastic pipe cannot be that close to heat. We decided to remove the water heater, which is quite old, and install a gas on-demand hot water unit which avoids this problem. There is plenty of gas capacity.

On the shear effect of the subfloor I’m removing (have removed) . . . the bathroom is a bumpout, extending past the foundation, the bumpout sits over a dirt crawlspace with some 2x10 joists on some, um, not very engineered looking supports. I think the bumpout and its structure, such as it is, are pretty irrelevant to the earthquake resilience of the building. It will probably fall off.