Water issue in bathroom at base of the tub and shower plumbing wall

[NotEnoughTime]

I am troubleshooting a water issue and I am looking for ideas on how to identify the source of a water leak.I remodeled my basement bathroom February 2009. I had a room mate living in the basement and he used the shower on a regular basis. I however did not use that bathroom. Water issues started to appear mid 2011. The first signs I noticed were bubbling paint. I noticed small gaps in the caulk between the tub and the tile and assumed that to be the cause. I removed the caulk, setup a fan and dehumidifier. The bathroom dried out for a full week before I replaced the caulk. I waited another week before allowing use of the bathroom. The bubbling paint returned within a few weeks and seemed to worsen more rapidly this time. Now I suspected there was a leak inside the wall. I had a outdoor spigot that leaked when in use that was located in the block wall behind the shower wall. I had long since stopped using the spigot but I suspected that was the source. I opened up the wall to view the plumbing for the shower. It appeared that the water was not coming from that spigot. What I saw confused me even more.Just to be sure I fixed the spigot behind the shower wall by capping it off completely. My room mate has since moved out and the paint still appears to be bubbled out. I now suspect a small leak that is accumulating between the durock and tile and running down the front of the tub and soaking into the base of the wall. I have tried running the shower for ten minutes straight and I don't see any leaks anywhere. There is no immediate moisture build up. The shower has not been in use for a few months now and the bathroom still smells musty. As for further troubleshooting I am stumped. Can anyone suggest some troubleshooting steps to take next?I have attached various pictures to help show what is going on.I noticed moistrue at the base of the shower wall inside the wall. After setting up a fan and dehumidifier the moisture has not returned but the paint is still bubbled out.Also there appears to be some droppings of some kind inside the wall, this seems strange. Any ideas what these are from?I have many more pictures but didn't have time to post every single one. Any ideas or advice would be appreciated! As a side note I tried formatting this post better but for some reason it keeps dropping my line breaks.

[pushkins]

It certainly appears as a moisture issue with the bubbling paint (once it bubbles, it will never go back) along with the obvious moisture in your pictures. From your pictures and your description it doesn't seem to be coming from the valve, you said you ran it for a period of time and saw no leaks. Have you checked the drain under the bath, a leak here will only show up when in use and could be just a small leak, sometimes only when there is weight in the tub. Do you notice any movement in the tub when you stand in it (or flex) ? If the faucet was leaking inside the wall it would be very obvious, most often it would leak if it was on or off and even a small leak (pin hole) would be very easy to see. Check the caulking of the tile to tub, this is another area where small amounts of water can leak and over time cause the damage your seeing. Corners of tiled walls are another area to check. The picture of the durorock moisture issue where is that exactly ? As a note Durorock is not water proof it is a cement product that won't fall apart if it gets wet nor will it allow mold to grow if it does get wet. In reality the backer board shouldn't get all that wet as the tile and grout should shed 95% + of any moisture, that's why I asked about the caulking, if there is a crack or missing caulk that would allow water in onto the durorock.

[pushkins]

It certainly appears as a moisture issue with the bubbling paint (once it bubbles, it will never go back) along with the obvious moisture in your pictures. From your pictures and your description it doesn't seem to be coming from the valve, you said you ran it for a period of time and saw no leaks. Have you checked the drain under the bath, a leak here will only show up when in use and could be just a small leak, sometimes only when there is weight in the tub. Do you notice any movement in the tub when you stand in it (or flex) ? If the faucet was leaking inside the wall it would be very obvious, most often it would leak if it was on or off and even a small leak (pin hole) would be very easy to see. Check the caulking of the tile to tub, this is another area where small amounts of water can leak and over time cause the damage your seeing. Corners of tiled walls are another area to check. The picture of the durorock moisture issue where is that exactly ? As a note Durorock is not water proof it is a cement product that won't fall apart if it gets wet nor will it allow mold to grow if it does get wet. In reality the backer board shouldn't get all that wet as the tile and grout should shed 95% + of any moisture, that's why I asked about the caulking, if there is a crack or missing caulk that would allow water in onto the durorock. The Duroock should also stop on top of the tub flange, this helps alleviate any moisture wicking up from the tub sill.

[NotEnoughTime]

More pictures and some followup questions.Today I opened up the wall more and when I vacummed up the mess the whole bathroom began to stink. My wife said it smelled like a dead animal. It didn't exactly smell like sewer, but it was bad. I noticed that there is large gaping hole that leads under my house. Should I close this hole up somehow?If it were the connection to the sewer line that was leaking gas is there an easy way to check for a leak?Also I noticed some droppings or dead bugs or something. There are two pictures with brown spots. Any idea what that could be?I popped off one of the tiles that covers the tub flange and all the screws underneath it are rusted over big time. Is this normal or just more evidence of a water problem? Also the caulk in this area on the inside of the wall is all black, like it was covered in mold.

[LazyPup]

I would begin by checking the easiest overlooked, yet most common source for your problem.

The shower arm connection.

If you note the photo of your shower mixer you will see that the greatest evidence of water causing discoloration on the pipes is on the center pipe, which is the riser up to the shower head. If you have even a slight leak at the shower arm connection the water will either spray out against the backerboard or it will come down the exterior of the shower riser pipe by surface tension, then drip off and cause what appears like a leak at the valve and that dripping water will hit the 2x4 sill plate on the bottom of the stud wall, then migrate out and cause the damage at the base of the wall like your experiencing.

If your shower riser was installed correctly there should be a "Drop Ear 90Deg Elbow" on the top of the riser. A drop ear 90 has a solder connection on the input where its attached to the copper riser and it has a Female Iron Pipe threaded outlet, where the chrome plated shower arm is screwed in and it has two little ears projecting out on the sides. Properly there should be some wooden blocking directly behind the 90 and screws are put through the holes in the ears and into the wood blocking to hold it securely in place.

This problem is commonly seen in DIY installations because the DIY'er dosn't know any better, but sad as I am to have to say it, there are also many cheap or lazy plumbers out there who just solder a standard elbow on top and stub out to a female thread adapter. Some may go so far as to install some blocking and perhaps put a pipe hanger around the pipe, but even with that, it is not enough.

Add to that, they are probably using that cheap single density PTFE (teflon) tape that you find in the hardware stores on those little white rells with the red or blue caps for about $1. (that tape is only certified for use on threaded fittings up to 3/8"). Properly they should use the Yellow "triple density" tape, and when applying the tape you begin by wrapping three full wraps flush with the end of the thread, then begin winding it up the thread by overlapping whats on the thead by 1/3 and continue with the 1/3 overlap until you wrap all the way up to the end of the thread.

Personally, I prefer to apply a good thread dope. (My first choice of thread dope is Non-hardening Rector Seal)

When a pipe threaded joint is made up properly there should be no more than 1 full turn of the thread left visible, but sadly many people put them in hand tight then just give it a turn or two and think that is sufficient.

And here is a very important point when making up a threaded pipe joint. When you come to tle last turn, make sure you stop exactly where you want the finished joint to be. DO NOT UNDER ANY CIRCUMSTANCES unscrew the pipe, even in the slightest to get finale alignment. Unscrewing even as little as 1/10 of a turn to align your shower arm or valve will nearly always eventually result in a leak. If you turned too far the first time, unscrew and remove the pipe, clean the threads and reapply your tape or dope then start over and pay more attention to detail this time...LOL