Replies

1. 
   DanH | Aug 12, 2011 09:40am | #1

   That's basically just soap/hard water scum that collects in the joint.  It may help to COMPLETELY clean the joint, then caulk with a good-quality bathtub caulk.  (Can't tell from your description what the shape of the joint is and how well caulking will work.)  The other thing that helps is to use a post-shower spray such as A&H Clean Shower.

2. 
   calvin | Aug 12, 2011 05:43pm | #2

   running out when showering..................

   You need to find the source of water that is getting behind your shower and "leaking out" of that seam.

   If you clean the blank gunk now and manage to get it all done proper-you will find the problem expanding on the backside of that shower enclosure if you caulk it in now. 

   Find the source of water-perhaps a leaking fitting up high-the shower head extension behind that escutchion would be a place to look.

   If the seam is below the faucet or spout, that might be a source. 

   Is the problem at the plumbing end?

   Is it at the front of the tub?

   Is the drywall damp or punky at the end of the seam?

   Are there doors on the tub or just a curtain.

3. 
   calvin | Aug 12, 2011 10:11pm | #3

   Dan

   I do this for a living and have for the past 39 yrs.

   Remodeling is my business.

   It can certainly be soap scum

   But more often than not, it's water getting behind the panels, drifting down and collecting on that channel you think holds soap scum. 

   So BS that.

   thanks.

1. 
   DanH | Aug 13, 2011 08:12am | #4

   And if this were happening, wouldn't there be other signs?

1. 
   calvin | Aug 13, 2011 07:03pm | #5

   well, I suppose there could be.............

   but, what was given in the information suggested to me my response.  I asked for further clarification.

   The reverse water flow you brought up doesn't jive with the way most of those pcs/parts tub / showers are constructed.  Most if not all have a high lip on the lower section with the upper pcs. having a lip that goes over that.  Water can run uphill, side hill and the ever popular downhill.  Still, I've taken out many units, installed even more and what needs to be done oftentimes is more than the instructions. 

   For instance, the horizontal seams are supposed to expel any water that gets in that area as well as what sometimes happens-water from above that travels down the backside of the upper panel and enters the seam area.  Some will advise or take it upon themselves to caulk that seam shut.  Now, the water than can get behind that seam area has nowhere to go.  Mold funk, yuck.

   I've recaulked a boatload of seams and after removal of the old caulk I blow out the seam with a hairdryer b/4 recaulking.  Sometimes there's some serious juicy ugly funk that streams out.  Where did it come from?  Back into the seam from some minute pinhole in the caulk?  Maybe.

   One recurring problem I deal with are the punky drywall just outside the surround AT the seam.   Water freely enters even the caulked seam and slides along the side to the vertical fastening lip of the panels.  There is saturates the drywall that covers the fastening flange.  You must caulk a dam from the very back of that seam so water stays away from the flange and covering drywall.  

   Another port of entry is the shower door vertical channel.  You see no water outside the enclosure, yet that seam drywall area still gets wet.  The how does water get there question can be assigned to the 3 or so screws that fasten that door channel.  After drilling for the fastener but b/4 mounting, those holes should be filled with caulk and so should the hole in the door channel.  Then when you run in the fastener there's little chance of the water that runs down the glass/channel area entering behind the door channel and finding it's way to that seam  that we're talking about.

   So yeah, there's probably a boatload of things that could cause it.  Pick one.

1. 
   DanH | Aug 13, 2011 10:13pm | #6

   Most if not all have a high lip on the lower section with the upper pcs. having a lip that goes over that.

   That's exactly what I said.

   I'll grant you that IF the "mold" is appearing mainly in the area directly below the control and shower head that it's possible that water is leaking in through a poorly gasketed control or is being sprayed back by a defective shower head.

   But if the "mold" is appearing elsewhere it's coming from inside the enclosure, not somehow leaking on the outside.  (There's no other source of water from the outside.)

   Certainly water will want to flow sideways along the seam, and this may make a punky spot in the drywall adjacent to the seam, but this essentially proves what I was saying, that water gets into the seam from inside the shower and doesn't leak out the back.

1. 
   calvin | Aug 13, 2011 11:12pm | #7

   Dan, you could be right..............

   but this essentially proves what I was saying, that water gets into the seam from inside the shower and doesn't leak out the back.

   This essentially doesn't prove any of the above.   Until Mike comes back and explains further, nothing is a given.

   Especially soap scum.

   Besides, I'm not thinking anybody was talking about water leaking out the back.  Where'd you come up with that?  He said the goo was running out the seam, when showering.  Why don't we wait till or if he comes back with some more information? 

   My point is that if he just cleans it up and caulks it, he may not have found the real cause of the moisture and the gunk.

   But, what do I know.  Just a dumb carpenter.

2. 
   Piffin | Aug 14, 2011 09:34am | #9

   My bet is that there is a leak behind this in the plumbing stand pipe from faucet control to the showerhead that only leaks when the shower diverter is employed. That projects a fine spray behind this FG shell that lands on the tub lip behind the seam, That water could be running a ways before coming back out where ti is seen by the OP

3. 
   calvin | Aug 14, 2011 09:47am | #10

   Paul

   The most common thing I find in these situations are poor fitting escutcheons and spouts that are not properly fitted to the shower enclosure wall. 

   When using the tub, not much water up high.  Showering, water cascades down the plumbing end, seeping into openings at the faucet and control trim.  Not much, but constant-day after day.  B/4 the plumber installs the trim, I caulk a damn over and down both sides of the drilled opening in the enclosure wall, leaving the bottom open so any water that does get behind the trim will be diverted around and out.  Those rubber gaskets on the back of the escutcheons only make as good a contact as their trim.

   Same with the spout.  Depending on the fit of the plumber, it's possible the plastic wall can be pushed away quite easily, breaking the usual caulk detail around the spout/wall.  That interior caulk diverter helps eliminate water intrusion.

4. 
   Piffin | Aug 14, 2011 09:29am | #8

   Dan, you didn't read the description fully

   "What looks to be black mold has been seeping out of that seam recently -- to the point if I leave it alone it will really start coming showing itself, running into the tub during showers, etc."

   Running out during showers menas that water is getting behind there and then running out. A build up like you are thinking of just sits there looking dirty without doing anything else. The OP needs to find out hjow water is getting behind.

1. 
   DanH | Aug 14, 2011 09:56am | #11

   He said "if I leave it alone"

   He said "if I leave it alone" -- it's not constantly running down the wall, but will make an appearance if he doesn't clean out the joint.

   I'll grant you that there are scenarios where leaks could occur behind the shower enclosure, or water could leak behind the enclosure at the shower head or the control.  But with many/most designs for the joint these wouldn't cause leakage through the joint, and if there was leakage it wouldn't be that gunky, since you'd have clear water running through.

   What does happen, quite frequently, is for water to run down the shower wall and then be sucked up, by capiliary action, into any narrow cracks and crevices.  Slowly the water will evaporate, leaving behind soap scum, hard water deposits, and whatever else was in the water.  In very hard water this will build up as a white/grunge colored chalk-like substance, but in softer water it builds up as a black scum.  Mildew may contribute to the scum, but probably not in a big way -- it's just what you'd get if you boiled down a whole bunch of shower water.

   To prevent this there are several techniques.  A couple related to the design of the enclosure are to shape the joint such that capilliary action is minimized, and to make the upper section jut out beyond the lower one slightly, creating a sort of drip edge and also partially hiding the joint.   Otherwise, use of a "shower spray" (that is essentially the same as a rinse agent you'd use in a dishwasher) both beaks the capilliary action and helps the water on the wall to "sheet off" rapidly rather than slowly running down and getting caught in the joint. 

   And one can caulk the joint.  Though some water will often find a way behind the caulk over time, that small amount is harmless (at least until the caulk begins to fail and it begins seeping out again, at which point it's time to replace the caulk).

5. 
   dvitendi | Nov 02, 2011 08:33am | #12

   I don't know whether this will be of any use you as I am based in the UK, but the HG mold cleaning stuff really is a trade secret and works wonders. My shower enclosure was caked in the mould stuff after the winter period had passed - Nothing HG mould stuff couldn't get rid of. 

   Hope that helps!