I have a contractor installing a shower pan (mud pan). I have serious doubts about how this is being done. The shower is a walk-in, and being built on a concrete slab in a basement (the basement has never had any moisture problems).

My concern is that the contractor states that if a preslope is added under the liner, then the next layer of the mud pan (placed on top of the liner) will be too thin near the drain. I've provided some pictures here, since it is so much easier to see the concern:

pictures of the liner install

The contractor indicates that if the liner is placed directly on the concrete, then the liner will be firmly held to the slab and there will be a deeper depth of material resting on the liner to hold it in place.

My concern is, how then can water that reaches the liner drain to the center drain (it would then be the highest point in the floor). Also, with the way the liner is installed now, it seems there would be an air-gap all around the drain with a potential for the liner to stretch at the drain and possibly create a tear.

you could raise the drain probably an inch? and the curb if need be.I see from the photos your drain is recessed all the way.

Hi Mark,

Your concern is right on. Within a few months of using that shower you will have moisture trapped and that is NOT a good thing. To do the job right you need a preslope or change to a Kerdi Drain system. I don't understand your concern about air gap, there won't be any air gaps.

The contractor perhaps has never done a preslope? The preslope is bonded to the slab and only needs to be about 3/8" thick at the drain. From there it'll slope up to about 3/4" or so to the walls judging by the size of the shower. (1/4" per lin. ft. as you know). Over that you install the membrane then the finish mortar bed will be from maybe 1"-1 1/4"(?) at the drain to 1 1/2"- 1 1/34" or whatever at the perimeter.

I also don't like the way your curb is membraned, and how are you gonna waterproof the kneewall?

Jaz

Hi Mark

The inspectors in Fairfax County aren't too terribly picky about shower pans, but even they aren't going to let that one pass (assuming you are permitting this job).

There really isn't anything good to say about that liner, and I would insist on it being taken out and redone to the specs in the TCA handbook.

Jaz is right .... you either need a slope under the liner or a waterproof membrane like Kerdi to direct water straight to the drain.
If he's using the correct drain assembly ... the trap will adjust to allow for almost 1-1/4" of mortar bed at the drain.
All your concerns are ones you should confront your contractor with so that he's aware you're not going to settle for an improper shower pan.

Thank you Jaz,

Some elaboration:

I don't understand your concern about air gap, there won't be any air gaps.

-Jaz, I am referring to the area under the membrame at the drain ring, if there is nothing filling the void, then there will be an air gap where the membrane transitions from the floor and rises to meet the drain ring. I doubt that the fill material will provide enough compression to force the membrain tight to the drain. Either way, it is clear that this particular install is not satisfactory.

I also don't like the way your curb is membraned, and how are you gonna waterproof the kneewall?

Yeah, I'm not so fond of that either. I think the plan is to put Durarock or green board on the knee wall inside the shower and on facing parts of wood. Outside the shower will be drywall finish.

A good source for purchasing a Kerdi-drain would be welcomed (I could just get one for the contractor to make his life easier).

Yep, it's permitted and the inspector has been by once already.

Don't even think about greenboard for any part of your shower. (Pure garbage)

Stick with cement board for all the tile backer.

Hope your liner issues get fixed up.

If the problem is that the male end of the drain piece isn't long enough,then take it to a good plumbing shop and they can glue on another section of threaded ABS or PVC.

Mark

Did the Fx County inspector let that pass?

Let's put it this way, there have been 2 inspectors that have had opportunity to look at this. Neither raised it as a concern. However, it seems they will change/add opinion add any time in the completion stages. So, I can see them letting it go for now and then coming back and asking for a change.

I am working with the contrator to start this part over, including the installation of a Kerdi-drain which was recommended earlier in the discussion thread (a great, but pricey option).

Ok, you have a Kerdi drain, did you get the Kerdi membrane? How are you going to preceed?

Jaz

I've not purchased the Kerdi drain yet. I was looking for a local supplier.

Jaz,

We're going to go with a normal Oatley brand drain. Contractor is adding the preslope and I purchased a Oatley brand CPE membrane liner, 40 mils thick. I do have a 2 more questions for the group:
1) Can the contractor use normal (Acrylpro brand) ceramic tile adhesive to fix the Oatley membrane to the pre-slope (obtained from HD). I've seen pictures on this site where others have glued the underside of the liner to the pre-slope, but no mention of the adhesive used. BTW, I tried to find a local supplier of the Chloraloy brand CPE liner, but no luck. Hopefully the Oatley will suffice.

2)I've seen pictures of folks using the Laticrete 9235 to seal the entire shower before setting tiles. Can you use just the normal tile adhesive (again, Acrylpro brand) to adhere tiles to the Laticrete? I think Lowes sells the Laticrete, so I was going to buy and install it as an extra measure of safety (peace of mind).

Thanks to everyone here in helping to guide me along. When I'm done, I'll update the link above with final pictures. It sure is a great help to ask a forum of pro's on how to make sure it's done right!

No photos like that on this site Mark. The liner should lay freely onto the pre-slope and attached on the upper edges away from the floor and on the outside of the curb.

I'm not sure what the Acrylpro people say about their product, but I'd suggest using a good quality polymer modified thinset mortar of any brand to bond your tiles. It will bond well to Laticrete 9235.

I think Acrylpro is a mastic? I don't know of any sheet membrane or liquid membrane that is compatible with mastic. Lat 9235 is what I use on all jobs, and it requires a quality latex-modified thinset for bonding tile.

Acrylpro is a type 1 mastic from Custom Building Products.

Manufacturer actually states it can be used in wet areas of prolonged water exposure. But not on shower floors.

I personaly would stick with a modified thinset as Harry suggested.

I'm not sure what the Acrylpro people say about their product, but I'd suggest using a good quality polymer modified thinset mortar of any brand to bond your tiles. It will bond well to Laticrete 9235.
[/QUOTE]

You are correct Harry, I saw the picture on a different ahem) website. Just goes to show that misinformation can be found everywhere. I apologize for the erroneous reference.

With regard to the thinset, the contractor bought a Versabond Fortified Thin-Set mortar (again, another HD purchase). I'm wondering if this will bond well to the Laticrete, the material sheet says the following,"General Surface Preparation:
Surfaces must be structurally sound, clean, dry and free from grease, oil, dirt, curing compounds, sealers, adhesives or any other contaminant that would prevent a good bond". By "sealers", does that mean the Versabond will not hold to the Laticrete? Also, we are putting a tan color tile with a "sand" color grout, they bought a grey color thinset - will that grey be a problem - should I have them get white color thinset.

- thanks again for the guidance.

We're dumping the mastic, see my reply to Harry.
BTW, thank you for the Laticrete reference - looks to be a great product.

Oh, and it's not at Lowe's, they were useless just trying to look it up. I used the Laticrete website to find a provider - closest was a specialty tile store about 45mins. away.

WHere did you end up finding the Laticrete 9235? I buy it at Conestoga Tile, which is near Dulles Airport.

Regarding the Versabond...technically,as a modified thinset, it will stick. But I am less-than-impressed with the quality of Versabond. It really varies in consistency, sand size, and stickum from one bag to another. If your contractor wants to use Custom products, I suggest using Flexbond (also sold at HD). It is an excellent thinset.

BTW, we start a new job on Tuesday in Fairfax City. We'll be using 9235 there. Where in FX are you, the City or County?

Hi All,

Hey, sorry I haven't contributed the last few days, just returned from the SURFACES 2006 Show in Las Vegas this morning....I figured one of us should go.....

Jaz

Found a tile place off 395. We're in western Fairfax County. ok., so I'm going to have them use the Flexbond in white.

thanks again for the help Rob Z.

Jaz ... lose much money on the slots?

Absolutely Harry, isn't that why they were invented?

Actually not that much. I decided to go only because I had a free airplane ride. I was only planning on attending Coverings in Orlando in early April. So I just went for a cheaper hotel off the strip. I took the monorail to the strip and so I had to walk thru Harrah's and then thru the Venetian to get to the Sands Expo. Darn if I didn't stop the try my luck each time.

Jaz