I spent my afternoon working on the mop sink area:
Primary tasks today were to cut a 2½” hole through the cement board, the insulation, and the siding for the drain line to exit through and cut a precisely sized, perfectly square hole for the access panel (below the faucet). I accomplished these but it took 3 hours to do it.
To determine where that hole in the cement board went to make the whole thing fit, I needed to get tricky about measuring the height of the drain pipe when it’s installed. There is no room to work down there, so I spun the trap assembly around so the discharge pipe was close to the outboard edge of the basin, then I could get an accurate height measurement. Then I stood a piece of 3″ pipe in the drain hole of the sink and spray painted the floor around it. That gave me a definitive reference of where the drain is so I could remove the sink and work at laying out the hole on the cement board and cutting it.
Then I made a template (accounting for the sole plate in the wall and using a wall stud as locator) to use in transferring the hole to the siding so the two holes will line up perfectly. I also used it to trace the circle on the insulation which I did not staple in place in the lower part of the wall. That way I could pull it up and out of the way to get to the siding, and I used scissors to snip a tunnel through the batt. For some strange reason, it all lined up well.
I have NOT glued anything together or permanently installed the cement board. I’ll need to move all of this out of the way when Robert Gann comes to run the water line in and install the supply lines. That will require drilling through the studs and running pipe to the faucet. I did staple the insulation in place. That’s an 8 inch thick wall with plenty of room for insulation and plumbing.
Next step, level the floor under the sink so the cement blocks it sits on will be level and the sink will sit squarely atop the base blocks.