View Full Version : Shower Floor Leak Inside

06-25-2007, 04:33 PM
I have a cultured marble shower. The floor is a solid piece. I have caulked the floor edges all around a number of times and unless I am just not doing it right after a few months, or sometimes a few weeks water comes out from under the caulked area (I use Silicone II). Nothing leaks outside the shower. What I do not understand is if the base under the floor (I've got a pan, then the mud base, then the marble or whatever it's made of floor that you stand on) is supposed to absorb water, but then drain it to the drain, why would there ever be a large enough buildup of water up the sides of the pan to allow pressure on the back of the caulk to cause it to push through? One thing to add. A repair guy came out once to fix it and after taking off all the marble at the base accidently cut the pan about 3 or 4 inches off the floor. I sealed the small cut with rubber cement and some plastic covering. Now, that hole appears to leak a little because I notice that some wood molding on the outside of the shower, where there is no marble, gets wet. That means that water must rise behind the marble sides in the shower, up the drain pan side at least 4 inches to reach that cut on drip through. I can't understand how so much water can get that high. Shouldn't it drain out the shower as soon as it gets even one inch high?

06-25-2007, 05:08 PM
You have me confused as to what you have. A cultured marble shower base normally does not have a liner. Then you mention a mortar base.

If it is a tiled base with a liner, it sounds like the liner was installed without a preslope - i.e., the liner was installed flat on the floor. If that is the case, especially if the weep holes are blocked, will allow water to accumulate under the floor. If that is the case, that moisture will prevent the caulk from lasting.

06-26-2007, 06:30 AM
Thanks for the info. I have pictures I took when the house was built. The shower was framed and a liner installed. Then they filled the liner with mud. Then they placed a floor, not made of cultured marble, but something that was white, pebbled or so, that covered the entire floor and rested on the mud. The shower is big, at least 3 by 5 feet. Then they caulked the base and the vertical sides that covered the framing. The caulking lasted at least 10 years, before it started to leak. But what I don't understand, unless as you say the weep holes are clogged (how do I unclog them?), is how does water fill up so high to get to the caulk and run out? The mud is at least an inch thick and the base that sits on it is also an inch thick.

06-26-2007, 07:03 AM
To work right, the liner must NOT be flat! Water needs to run downhill. Therefore, the liner must be on a sloped bed (called a preslope). If yours is on the floor, then two things, it almost always has to rise up a little to get to the weep holes, and if they didn't do a preslope, they probably didn't put something around the weepholes to keep them open. As a result, over the years, the shower floor has been accumulating water. The tile and grout are NOT waterproof, and can let a little moisture through. It can take a long time to accumulate, but eventually, any shower built with the liner flat on the floor starts to have the problems you indicate - the grout never dries out, mold starts, caulk won't stay in place. Moisture is probably wicking up the walls from the saturated shower base. If the liner was on a slope, and the weep holes (just above the clamping liner) were open, that moisture would have a place to go. That can't happen if the liner is not sloped (i.e., flat on the floor). The only way to fix this is to tear out at least the bottom of the shower and up the wall high enough to install a new shower pan with a new liner. All of the caulk you can put on there is only a bandaid. Showers that have a liner flat on the floor usually start to smell like a swamp after awhile, too. Seek some other opinions, but I think you'll find they agree with me.

A good place to discuss this is www.johnbridge.com (http://www.johnbridge.com). Read a little there after using the search function, and you'll get numerous examples of nearly exactly the same thing.

There seems to be a huge number of installers that seem to think the laws of physics don't apply to a shower floor (i.e., water flows downhill) that would never consider putting in their drain lines with no slope. The liner is your waterproofing...caulk, tile, grout helps, but if the liner isn't done right, you've got problems.

06-26-2007, 07:14 AM
consult the pictures again; see if the liner was installed on a flat surface.

Otherwise, some significant work had to have been done to make a sloped surface that drained into the drain before the liner was laid. You would know if that waterproofing liner was installed on a pre-slope because the liner on a slope would be slanted towards the drain on all sides, either like an inverted cone (smooth all around) or like four flat planes that cause creases where they meet, visible as bends going from the corners to all meeting at the drain.

99.99% sure you don't have this if your cultured marble is all in one piece. FYI, an inch or two under the drain cap, at the almost invisible weepholes, is where water would slide into the drain (percolate, capillary action). It would seep over because of the force of gravity (because of the 2% slope), and because new water is gradually sinking in forcing the old water to seep out.

Now, after years of slow accumulation, you have a waterlogged flat pan. So, this means your installation has reached its lifespan. FYI, the plumbing code does not prescribe this; in fact, the code says that the liner must be installed on a presloped surface. Very few plumbers mention this; it is a half-sentence often overlooked. Besides, plumbers don't install liners, they just tell you to do so. It is unfortunate for you.

Very few things are truly waterproof when subjected to H20 molecules on a constant basis. Water sliding down the walls eventually gets through the caulking. Water can slowly penetrate cultured marble too. Humidity, moisture, vapor, a few molecules at a time, it all adds up to create visible water when the direction of flow is one way all the time.

(edit: Jim posted while i was writing out my response. It's the same idea.)

06-26-2007, 07:16 AM
Your post makes, unfortunately, 100% sense. I've looked at the pictures I took when it was built. I can see the framing, and I can see the pan stuff going up the sides a bit and around the framing. I did not take any pictures of them actually doing the pan, but the picture before the pan was in shows just the framing on the slab. I do not remember them putting down any concrete or whatever to form a slope on which the pan would be laid and in all the pictures the pan looks flat. But, when I go to see houses being built, I don't ever remember seeing anything at the bottom of new showers, prior to the pan going in, that looks like anyone is trying to build in a slope for the pan. Seems to me that to do that everyone would have to pour in some mud, within the framing of the shower, to create the upslope for the pan. All the ones I've looked at look flat. Plus, I read someplace, don't remember where, that there is always water under the bottom of showers. Be all that as it may, I've got a problem and it looks like the only solution is going to be to tear it out and redo it. And I still have to deal with the small cut in the pan at the three inch level. Thanks for the good info again.

06-26-2007, 08:36 AM
The pan liner needs to be waterproof above the curb, so in case the pan gets full because the drain is blocked, it can contain the water. So, depending on where that cut is relative to the top of the curb, it may not be a factor at all.

As noted, many installers ignore the fact that water flows downhill, assuming that the tile and the upper slope of the floor will prevent any water from getting below that top surface...will never be 100% effective, that's why the requirement for the preslope.

There are some systems that are even better, IMHO, Kerdi is one of them. This makes the entire shower waterproof right under the tile layer. Thus, no setting bed to accumulate water and no weep holes, no caulk failures since the whole thing dries out very quickly with just the thinset underneath the tiles. Wedi is another, but instead of it being a surface applied membrane, it is a waterproof wall. Note waterproof in both of these situations, not water resistant, and there is no water absorbtion for all practical purposes.

06-26-2007, 10:00 AM
... I do not remember them putting down any concrete or whatever to form a slope on which the pan would be laid and in all the pictures the pan looks flat...typical, not unusual. Totally normal when a single piece of cultured marble is put down. But not Code. The norm, but not good.

From last week:

these are recent threads that discuss one or another of the same problems you are facing. In one case, a post says CBU (cement backer unit) board is the best, without saying that one needs a plastic sheet underneath it. That is common, but strictly speaking not bulletproof.


06-26-2007, 11:54 AM
After reading all the replies something just clicked. I've noticed that the caulk that leaks only leaks mainly leaks only on two of the six edges of the floor. Both edges are in one corner of the floor. The floor is sort of hexagonal in shape. So it occurs to me that this is happening because the mud base underneath is not level and the water tends to pool on one side. Did I mention too that when I jump up and down on the floor I can hear a water sucking sound and, also, water tends to well up around the center drain when I do that?

I guess I just have to accept the fact that the only fix here is to take it out and start over, so I've started contacting people who do bath remodels to see just how bad this will be.

Thanks for all the education and advice.

06-26-2007, 12:11 PM
The whole pan is saturated because of the simple neglect to put the liner on a presloped bed. And the weep holes are above the liner, and probably clogged because of incorrect installation. Simple details, often overlooked. The installers get away with it because it doesn't actually leak, and the symptoms often don't show up until well after the typical 1-year warranty. Do some research, find out how it should be done, then stick to your guns about getting it fixed.

Keep in mind that matching tile will be tough, and the majority of the costs are usually in the pan. It might end up not being much more to just tear it out and start over with tile you like, a new shower valve and maybe a new P-trap. Spend some time reading over at www.johnbridge.com (http://www.johnbridge.com), and ask questions as well. You'll get the idea of how to build a shower that will last, and even if you have it done rather than doing it yourself, you'll know what to ask and insist during the construction so it will last longer the next time.

A properly constructed shower pan should never have any appreciable liquid water underneath the tile. Plus, movement indicates other quality problems as well.

06-26-2007, 12:23 PM
I just thought of posting some pictures to show what I've been talking about.

Shower-00001 gives you an idea of the shape of the floor.

Shower-00002 shows one corner of the shower with the lower 4" marble removed. You can see the floor piece and the pan. It's here that the pan has a small cut about an inch below the top.

ShowerDrain-00002 shows the metal insert on which the drain cover goes to prevent anything falling in. You can see it's all brass and the downtube stops about 2" down. It connects to NOTHING. If I put my hand down it at the end I can feel space between the bottom of it and the mud base or at least something concrete.

I had first thought that the reason water was getting under the floor was because of this gap. So I got some PVC pie about 1 1/2" in diameter, with a flange, and dropped it down the hole so the flange rested on the brass and the tube end went down 6". I caulked it very heavily all over the brass top so that no water could come up and the shower water would rain into the tube and exit below that 2" mark. I did this also because I had noticed that when I jumped on the floor water came up around the outside edge of the round brass insert. For at least a year or better I had no leaks, but then it all went south.

Today I removed the tube and the caulk. Mainly because it doesn't seem to be fixing the problem and, after reading about allowing certain size of drain, like 2 1/2", I figured it wasn't helping being only 1 1/2". Plus when I have plumbers and others out here I want them to be able to see what we have. Water gushed up around the brass insert where it fits in the floor piece. And man, does it stink, like water in the bottom of a ship, really bad.