After many false starts (misdiagnoses from plumbers supplied by our home warranty company), I've pinpointed that our upstairs bathtub leaks when draining from a bath. It will not leak with a shower or if you only put a small amount of water in the tub. I've read the other posts in the forums about these leaks and lament that I don't have an access panel to check the pipes. Am I correct to assume that my only solution is to cut into the ceiling of the floor below and track it down that way?

Thanks!

After many false starts (misdiagnoses from plumbers supplied by our home warranty company), I've pinpointed that our upstairs bathtub leaks when draining from a bath. It will not leak with a shower or if you only put a small amount of water in the tub. I've read the other posts in the forums about these leaks and lament that I don't have an access panel to check the pipes. Am I correct to assume that my only solution is to cut into the ceiling of the floor below and track it down that way?

Thanks!

Rather then tear up your ceiling why not cut in a access panel behind the tub. You're going to have to have one anyhow and even if it's exposed you can "pretty" it up with a frame. If your home is under warranty, insist they provide you with a access panel. If they balk quote them section 1602.9 and 1602.9(a) of the Standard Plumbing Code which states;
"Sufficient access SHALL be provided to enable all pipework to be tested and to provide reasonable access for cleaning and OTHER NECESSARY MAINTENANCE. Our local codes insist on providing access panels on all the bathtubs we install. Let me know how you make out. Tom

Before you do that, I would see if Tom has a trick to save you. If not, use a razor knife, not a box cutter to cut the drywall down the center of the joist. Likely being fairly new, it is screwed on and you may be able to find and back out the screws. In cutting cross wise to the joists, a saw may work better. Better to make too big of a hole in the first place, than to have to make it bigger. Work carefully, and you may be able to reuse the drywall you take off. Otherwise, you may have to buy a whole 4' x 8' sheet.

When finished, screw the drywall back on. It should be 5/8'' rather than the standard 1/2'' used on the walls. It may help to back the seams without a joist above them with a piece of wood, or even glue on some drywall. Apply fiberglass mesh drywall tape to all the joints, apply spackling compound, and sand. If it isn't smooth, apply more compound and sand until it looks nice. The seams will leave a little thicker places, but if feathered out good, will hardly show.