hardware for copper pipe strap

Renovating a small old two-story duplex to rent out, which has been a long process. The apartment downstairs finally ready to rent, and the renter is raring to move in- in fact has already transfered electrical into their name. Just as a last check, I thought I would double check all the fixtures in the unfinished apartment above. Ran the shower and tub at full blast and went downstairs into lower bathroom. Drip... drip... drip. :wall: I got into the ceiling over the shower downstairs, and I can see water dripping from two places- one strangely enough is the bottom seam of the vent stack, where the tub drain meets the vertical sewer pipe. This is higher up than the downward bend of the drain (??). The only thing I can think of is a blockage further down the stack, but the tub appears to be draining fine, not even slow. The other dripping is happening from somewhere where the pipes meet the tub high up, which I can't really see looking up through ceiling from downstairs below. Anyone have any suggestions or seen this before? There's an old drain trap on the way to the vertical stack but the house was built in 1920... I've already been warned when these really old galvanized traps are opened they may never seal again. Might have no choice but to chance it :/

All of a sudden I discovered some dripping from the kitchen ceiling on to the counter/stove below. I cut open part of the ceiling with a jab saw (first pic). The sheetrock was already water sogged and parts of it came crashing down. I suspect this leak has been going on for days or weeks. When I poked my head through the ceiling hole for a closer look, I noticed the water was coming from different places of the plywood above. Some of it was leaking down from where the pipes run into the plywood, though there are some other places also, see pics. In these pics, there is one copper and one PVC pipe. Both are going up into the plywood above. Right above the kitchen is the bathroom with a ceramic tile floor. I'm assuming that the ceramic tile sits above the plywood I saw from the kitchen ceiling hole. I did not notice any leaky pipes, elbows or joints that were visible in the space between the ceiling and the plywood. Also, I did not find any obvious leaks in the bathroom above, which contains the sinks, toilet, shower and bathtub, each with their own fixtures. So the source of the leak is a complete mystery to me. There is a drip every few seconds. It doesn't get faster or slower when any of the faucets, shower or flush are used. How should I go about investigating where the leak is coming from? I'm stumped. Any help or ideas will be appreciated. Anup