So, I have a split level house. My bathroom doesn't have any exhaust fans installed. After I have been showering for about 5-10 minutes, which is located on the top floor, my basement main cast iron drain pipe starts to leak through the floor down into the basement. Now my shower drain in connected below where the leak is occurring from. There is insulation between the main cast iron pipe making it difficult to see. That main cast iron pipe runs through my attic exausts at the top of my house. I don't know where the leak is coming from. Im going to check the boot on top of my roof. Any other ideas where it could be coming from? Is there something in my attic that could help. Currently it drips right through the insulation. I have monitored the drain hose and no leaks there. Any ideas or places to start? Thank you.

Now my shower drain in connected below where the leak is occurring from.
That is not logical if the leak in in the drain. Water runs down hill.

Im going to check the boot on top of my roof.
That is not logical unless the leak occurs only when it is raining. The pipe that goes through the attic and roof is a vent pipe. The purpose of the boot is to keep out rain water.

I have monitored the drain hose and no leaks there
What does that mean?


Any ideas or places to start?

Suggest that you start by first determining whether the leak is in the drain system or the supply system.
Plug the shower drain. Fill the shower with a bucket and water from some source other than the shower. Let the water sit for some time (5 to 10 minutes). Check for leaks. A leak with the drain plugged would indicate a leaking shower pan.

Unplug the drain and add additional water as it is draining. Check for leaks. A leak during or after draining would indicate a leak in the drain piping.

Purchase a 1/2" PVC threaded pipe cap. Remove the shower head. Screw the pipe cap on the end of the shower arm. Turn on the water. Wait 5 to 10 minutes and check for leaks. A leak now would indicate a leak in the supply system. The most likely place for that to occur is where the shower arm screws into the 90 degree elbow of the shower riser pipe. Pull the escutcheon around the shower arm away from the wall. Using a flashlight, look inside the wall for signs of water. If necessary open up the drywall around the shower arm. This is the most likely place for a leak to occur. Especially if you have a pulsating shower head.

If no sign of water around the shower arm, remove the handle(s) of the shower valve and escutcheon plate(s). Look inside for signs of water. If you have an access panel for the shower valve on the other side of the wall, remove and look there for signs of water. Actually, this is probably the first place to look.

Ok so I tested the leak out a little bit more and have it narrowed down that I don't get any leaks if I run the bath water, if I run the shower after 5 minutes or so it starts leaking. Im starting to think the place to start is the shower arm. My bathtub is fiberglass with the shower arm and head sticking out of drywall. If that's not the problem, someone informed me, I might need to go up through my kitchen dry wall to get to the valve/leak

I don't get any leaks if I run the bath water
That is a strong indication that the leak is where the shower arm screws into the riser ell. Pull escutcheon away from the wall and look inside.