Bob's Curbless Shower Bathroom Remodel

[Bob V.]

It’s been awhile since I posted regarding my ongoing bathroom project. Progress has been slow due to work and family issues. But it’s time to get back to it…

The project is a total demo down to the studs with the removal of the tub, which is being replaced by a curbless shower for easy access for our handicapped daughter. The subfloor was removed, and an additional floor joist was sistered to every original 2x10 joists with PL Construction Adhesive and 3" deck screws in a zig-zag pattern every 6", to decrease the deflection of the floor. To accomplish the curbless shower, the subfloor in the shower area was lowered by trimming the top of the floor joists and then adding 2x8 sisters. The new floor consists of 5/8 ply subfloor under a ½ ply underlayment. A 2x6 supports wall was constructed in the basement to support the 14 ft span that the bathroom partially covers. Both the 4’x8’ shower area and the 8’x8’ bathroom area feel much sturdier, and pass the “Deflect-O-Lator” rating of L/5207 and L/1714 respectfully.

The new framing to create the shower area with a bench at either end is complete, along with the installation of the drywall in the shower and bathroom. Plumbing and Electrical has been roughed in, and the shower ceiling and bathroom area has been taped, mudded, and is ready for priming. I will be using Schluter products for this project, with Kerdi in the shower over the drywall and drypack floor, and Ditra on the bathroom plywood floor. The shower walls and benches add up to almost 200 sq ft, the shower floor is about 20sq ft, and the bathroom floor is roughly 64 sq ft.

The tile that we have chosen for this project is travertine of various sizes and textures, purchase from a local tile shop. They were not too keen on the idea of me using the Kerdi system, I think largely because of loss of sales of material. They want to push their products. I guess who can blame them, but I’m looking for foolproof results that will last. The Kerdi, Kerdiband, Kerack corners, Kerdifix and drain arrived last week from The Tile Experts, while the Ditra was purchase locally from HD. I plan on using Versabond modified thinset under the Ditra, and Kerabond unmodified thinset for both the Kerdi to drywall, and travertine to Ditra and Kerdi.

Now for some questions:
1. What are your thoughts regarding travertine in showers? Any special requirements?
2. Since unmodified thinset doesn’t do well with drywall joint compound, what method is recommended to seal the 2-3” band of joint compound on the shower wall where the wall and ceiling meet before the Kerdi goes up, since I plan on tiling all the way to the ceiling? Would typical latex or oil based primers seal the compound adequately for the thinset to adhere? Or since it is a small area, should I not be concerned.
3. I’d like to install 30 sq. ft. of radiant mat in the bathroom. Schluter recommends using modified thinset over the plywood floor; imbed the electric mat, and then the Ditra. But I’m concerned about the areas without the mat. Will the Ditra be lower in those areas, and the mat create a hump? Or since the mat is so thin, it is irrelevant? I know SLC could be used, but I’m trying to also keep the floor as thin as possible to match up with the height of the hallway. Keep in mind I’m trying to reduce a change in grade for accessibility.
4. I plan on first installing the Kerdi to the shower walls and benches, and then the granite bench tops and travertine walls except for the bottom course. Next I thought I would install the radiant electric mat and Ditra to establish the height or thickness of the shower base perimeter drypack which needs to be to match the height of the bathroom floor to create the curbless shower entrance. Are these steps in the correct order to accomplish getting the two floors at the same plane?
5. Any recommendations on a thin set mixer or tile saw and blade? There will be a lot of thinset to mix and some travertine to cut. I’ve seen ½” 9Amp D Handled drills at the local big box stores for $160. Kind of pricy. What about those at Harbor Freight? I’m also thinking about the Felker TM-75. Is that a good choice for 12-18 inch travertine and granite accent tiles?

That’s probably enough for now since more questions will probably follow as the project finally moves forward. See the attachment of the shower area looking down, and if you are interested; my previous posts for this project were at http://johnbridge.com/vbulletin/showthread.php?t=49767

Addition pics will follow as the Kerdi, Ditra, and tiles get installed. And as always, any comments and ideas will be greatly appreciated. This forum is the one of the main reasons projects like this are possible.

[conceptsplus]

I'll tackle one of them real quick. Some may disagree but this is what I would do. Don't use the ditra over the heat . Make sure your plywood is in good shape and well fastened- no sqeaks and or pops. Mix some multipupose thinset and skimcoat all the seams and nail holes, etc. Let it dry.

Install the warm wire.

Get a few cans of aerosol expanding foam and seal around the room along the walls, across the doorways, around heat registers (vents), along toekicks. Seal it all up with up with about a 3/8 consistant bead of the foam then let it expand and dry. Don't freak out if it expands to an inch in height, you'll cut it off flush later.

Prime the floor with the required primer for the slu, don't worry about it getting on the wires. Let it dry according to directions Then mix and pour the slu in a side to side motion starting at the furthest point away. Need a couple hands with this to mix and help keep it moving quickly. Keep pouring each bucket full so that it fully connects with the previously poured. Keep doing this until the desired thickness is achieved. Obviously, you'll want it to cover the wires. Remember , the faster you get it out on the floor, the better the leveling results. A good thick coat of primer provides a moisture barrier, which will improve the flow of the slu and keep that 20 minute working window open.

When it dries, check and make sure all wires are covered then cut off the eccess foam even with the dried slu, with a good sharp 4" scraper. Watch out for your lead wire! Don't want to cut that!

[Bob V.]

Bump

Looking for answers please. Yesterday's post was already 1 1/2 pages deep.

[ccarlisle]

Bob V

Yes, travertine is a fine choice for showers and IMO is the best natural stone to use there. Sure there are other choices but after having looked at marble, slate, sandstone, limestone and granite, I'd still put travertine in my shower. It has the best benefits/maintenance ratio to my way of thinking and by that I mean it offers the most (benefits) for the least (maintenance) keeping in mind that it takes a good installation at the beginning and that all stone requires maintenance of some kind throughout it's life. Properly constructed and installed, a travertine shower will outlast us. I'd opt for honed.

The underfloor heating mats I'm used to are about 1/8" thick and have not in my experience given rise to height issues compared to where they are not used.

I'd be careful with the floor tiles in the shower; if your daughter uses a wheelchair, her wheels put an extra stress on smaller tiles. Had a telltale experience with one inch tiles under a wheelchair...

[muskymike]

Hi Bob, I'm doing a travertine shower right now. It will need to be sealed with an enhancer or stone sealer and should be wiped down after each use. Kerdi is a great choice for your project. I did a shower similar to yours check it out
As for the heat mat, you can thinset it down and skim the rest of the floor to bring it to the same level as the mat. Then install the Ditra with unmodified thinset. You might want to look into a bigger saw for those size tiles. Felkers FT150 is a nice saw and you could sell it for almost what you paid for it.
I use a hole hawg for mixing thinset and for a blade any quality tile blade will work. Travertine is pretty soft.

[cx]

1. Travertine's fine. More maintenance than ceramic tile, perhaps, but I don't gotta do the maintenance, eh?

2. You should have no problem installing the Kerdi on that little strip of sheetrock mud. You don't really need the Kerdi to go that high, but if you wanna pewt it up there, I'd just do it.

3. What MMike said.

4. That should work.

5. A number of visitors have reported buying a half-inch drill at places like Harbor Freight to mix their thinset and it worked out fine. Be sure you get one with variable speed.

What MMike said about a saw. I think you could get by with the TM-75, but a bigger saw would be nice.

My opinion; worth price charged.

[Bob V.]

cx & Mike- Thanks for the suggestions. I'm priming the drywall shower ceiling tomorrow, along with the rest of the bathroom, and I'll take your advice and not worry too much about the small areas of joint compound that will get Kerdied.

And as far as the heat mat is concerned, could I put down the unmodified thinset on the plywood floor, then the roll of electric mat, and just thicker thinset base via a larger notched trowel in the areas without the mat, and then the Ditra? That way the electric mat and Ditra could get installed in one step. Or am I setting myself up for trouble? The mat area is the center 30 sq ft out of 64 sq ft.

Thanks your ideas of the half-inch drill and saws. I think I'll try HF for the drill, I'm not sure yet on the saw.

[Mike2]

It really is best to follow the installation instructions of the heating mat manufacturer, Bob. They vary somewhat and most offer several options. Tell us what brand you are using and we should be able to provide a link to those instructions.

Having said that, installing Ditra onto a thick bed of freash mortar does not sound like a good idea. Doing that may actually nullify the uncoupling qualities it has to offer.

[Bob V.]

Mike2- I'll be using a heat mat made by SunTouch. As far as installation with a uncoupling membrane like Ditra, they recommend to use the supplied doublefaced tape and hot melt glue and adhere the electric mat to ply floor, spread the modified thinset over the mat, and then the Ditra, in one step. This would seem to work if the whole floor is getting covered by the heat mat. But since I'm only covering the center 30 sq ft, I'm concerned about creating a ridge in the center of the room.

So I need to compromise on a method that will fit both the mat's characteristics and those of the Ditra. So I'm thinking of going with: Adhere the mat to the floor, applying modified thinset (Flexabond) over the mat, and a skimcoat of the same thinset in the areas without the mat. The next day, apply unmodified thinset (Kerabond) over the mat/cured thinset, and then the Dita. I'm hopeful that this doesn't increase the floor thickness too much. Any suggestion to improve/correct this method?

I had mentioned that I was planning on using travertine for this tile project and was wondering what the going price is. The local Tile Shop runs about $ 8 -10/sq ft. Is this typical? Yeah the square footage adds up... Just thought I'd ask what other people are seeing. The manager at the shop is really pushing for me to use their thinset and supplies, and states is better than the "junk" at the big box stores. According to him, their Pro-Lastic thinset is unmodified until adding the additive, and runs about $21/50 lbs. and $42/2gal. So he says I could use it without the additive for unmodified and with for modified. I don't want to be pressured to use something that will not work with the Shluter products, but I would still like to be able to ask him questions if needed. Any thoughts regarding Flexabond and Kerabond versus their Pro-Lastic?

[Bob V.]

I have been calling the local tile stores to try and find a source for the prefered thinset (Kerabond) to use with the Kerdi & Ditra. The local Menards sells Mapei products, but doesn't stock the Kerabond, only Keraset. A big difference, as discussed at this site in many posts. I could special order the Kerabond, and get it in a week or two. I continued to call other places and was told that Kerabond is always used with Keralastic, Mapei's Latex Additive. I explained that I was looking for an unmodified thinset to use with Schluter products like Kerdi and Ditra. Even with that info, I was told that the two always are used together.

Doesn't adding the Kerlastic to the unmodified Kerabond make it a modified thinset? Or have I misunderstood that when reading that Kerabond should be used with Kerdi that it was assumed that it was mixed using the Keralastic? Or am I confused with the terminology?

If Kerabond is unmodified when mixed with water, and modified when mixed with Keralastic, could the Kerabond/Keralastic system be used as the thinset between the Ditra and the ply floor?

These questions kind of go along with my previous post regarding the thinset offered at the Tile Shop in reference to their Pro-Lastic Thinset and Additive. Any comments and suggestions would be great help in sorting this out...

[Brian in San Diego]

Bob,

I hate to disagree with what a tile store employee has told you but you are correct Kerabond is unmodified when mixed with water and modified when mixed with keralastic. That being said I have found that the liquid additives are relatively expensive. So unless you only want to mix up a small portion of the Kerabond to make a modified thinset, I would strongly suggest you get Versabond at HD to lay the Ditra. A good slightly modifed thinset for a reasonable price. Truth be known you could get away with using Versabond to set your kerdi but in the interest of following the manufacturer's instructions you can order the Kerabond. I would use Versabond before I'd use Keraset, however.

I don't know about the stuff that the Tile Shops are putting in the bag. They more than likely are getting someone else's product brand named for them. Can't say one way or the other. If you have a Laticrete source in your area you could get Laticrete 317 Floor and Wall as your unmodified.

Brian

[Bob V.]

Brian- Thanks for the quick reply and info to confirm what I had been thinking all along. I'll stick to the Kerabond mixed with water for unmodified thinset, or look at Lowes for the Laticrete 317. The local HD does not have Versabond, but does have Flexbond, which seems to be an equivalent option, so that's what I'll use under the Ditra. Since I can't verify the properties of the Pro-Lastic thinset from the Tile Shop, I'll pass on that too.

Any comments on installing the heat mat under the Ditra, or the going rate of travertine?

[Bob V.]

bump

[cx]

Originally Posted by Bob

If Kerabond is unmodified when mixed with water, and modified when mixed with Keralastic, could the Kerabond/Keralastic system be used as the thinset between the Ditra and the ply floor?

Not sure how this got abandoned, Bob.

KeraBond mixed with water is a very good dry-set (un-modified) thinset mortar.

KeraBond mixed with Keralastic is a very good modified thinset mortar.

You could certainly use the Kera/Kera combination to install your Ditra to a plywood subfloor.

You could certainly use the KeraBond with water to set tiles to the Ditra.

If you instead install a heating mat system with the Kera/Kera, and cover it with that product, you would then install the Ditra with only KeraBond.

You could install the Ditra at the same time as the heating mat, but I think you'll be very sorry you tried that. Perhaps have that heating mat salesman come over and give you a demonstration first.

My opinion; worth price charged.

[Bob V.]

Well I'm finally ready to spread some thinset and get some Ditra and Kerdi installed. I'll be using Flexbond for the modified thinset for the Ditra to the plywood floor and Kerabond for the Kerdi to drywall and travertine to Ditra and Kerdi. But before I start, I have just a few more questions. My recent stumbling block has been the issue of installing 30 sq ft of heat mat in the center of the bathroom and compensating for the 1/8" rise in the floor in that area. Past posts have suggested different methods which all will work, but in the effort to keep the increase in floor thickness to a minimum for matching up with the hallway, I came up with a method I think will work pretty well.

After installing the 1/2" underlayment, using 1 1/4" screws every 6", and every 3" around the parameter, I cut a small groove with a router using a 7/32" bit. The bit normally used to make dados for 1/4" ply. The grooves were cut every 3" using a temporary fence screwed to the floor. At the end of each row I cut a connecting loop free hand to mimic the normal path of the warming wire. The warming wire was totally removed from the mat, laid in the groove, and hot glued where appropriate. The sensing wire was installed in the same manner, and both lines were then fished up the wall via pre-existing conduit runs to the location of the thermostat. Resistance readings were watched closely during this proccess to ensure that the cables were not damaged. Final results after a few hours are a warming mat installed at the same height as the floor, with no variations, and I'm ready for Ditra. Pretty slick if I do say so myself.

To protect the warming mat from damage while the shower work takes place, I'm planning on first putting down the Ditra in the bathroom, but not the floor tile until after the shower is done. I'd like to know what the height of the bathroom floor is after the Ditra, so I can match the height of the dry pack shower floor to it for the curbless shower. Will putting some cardboard over the Ditra while doing the shower be enough protection for all the traffic?
Please see the attached pictures for details on the warming mat and progress of the project.