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Bob V.
02-25-2008, 09:58 PM
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

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.

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02-25-2008, 11:05 PM
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.
02-26-2008, 04:43 PM

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

02-27-2008, 08:02 AM
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... :twitch:

02-27-2008, 09:56 PM
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.

02-27-2008, 10:08 PM
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.
02-29-2008, 09:23 PM
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.

03-02-2008, 03:50 PM
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.
03-03-2008, 10:33 PM
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.
03-04-2008, 04:15 PM
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
03-04-2008, 04:49 PM

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.


Bob V.
03-04-2008, 06:15 PM
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.
03-05-2008, 07:26 PM

03-05-2008, 07:49 PM
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. :shades:

My opinion; worth price charged.

Bob V.
03-18-2008, 08:50 PM
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.

Brian in San Diego
03-18-2008, 09:02 PM

I like the thought process and the ingenuity of "imbedding" the cables in the plywood. I can't say one way or the other if it compromised the strength of your underlayment/subfloor or if the method would be approved or not but quite ingenious nonetheless.

I put ditra down in my entry and did nothing to protect it for months. I walked on it everyday with no ill effects. I think cardboard would be plenty of protection for the Ditra. The height of the floor after the Ditra will be the thickness of the tile and the thinset underneath it. It it's ceramic tile I would guess the thinset would be close to 1/8" thick. That assumes that the floor is flat and level and you aren't using thinset to level the floor.


Bob V.
03-20-2008, 04:46 PM

Thanks for the comments on the installation method of the heat mat. I had thought about the effects on the underlayment/subfloor, but with sistered 2x12 joists, I felt that with less space between them, I could get by with the underlayment being slightly compromised. Spreading of thinset for the Ditra will go a lot better now.

The reason I'm installing the Ditra before working on the shower, is to allow me to find out what the final height of the bathroom floor substrate will be prior to tiling. Since the shower will not have a curb, don't I need to make sure that the perimeter of the shower floor prior to tiling, is at the same height as the bathroom floor prior to tiling?

I guess I'm assuming that thinset and Kerdi do not significantly increase the height of the shower floor enough to be of concern. But maybe that's incorrect. My goal is to have both the shower floor, after thinset and Kerdi, be at the same height, or on the same plane, as the bathroom floor, after thinset and Ditra. That's the reason for putting the Ditra in place first. Does any of this make sense, or am I making this all too complicated?

Another question I have is in regards to the order that the Kerdi, Kerdiband, and the prefabbed corners get installed. Does the Kerdiband go up first where ever the walls, benches, and floors meet, then the Kerdi, and lastly the prefabbed corners. Or does it really matter since they all overlap any way. Are there any recommended methods to reduce the buildup of Kerdi in the corners to keep things relatively flat?

Also, I'm wondering if the Kerabond thinset that I'll be using for all the travertine floor and walls, will be the correct thinset for the top of the benches that will be covered with two 16 x 24" pieces of granite? That is the same granite I plan on using for the vanity countertop.

Comment/suggestions are always appreciated...

Brian in San Diego
03-20-2008, 05:33 PM

I understand what you are trying to do and I know you aren't putting in a curb. Is there going to be a "speed bump" of any type? I guess from my way of thinking I'd want the bathroom floor to tilt a little toward the drain especially as it gets close to the shower but I don't see any problem with your idea. I think in your case I would kerdi band the seam between the ditra and the kerdi as well as the seams of the ditra near the shower. I generally discourage kerdi banding ditra because unless there is a way to contain the water it's going to go wherever it wants and having waterproofing under the tile isn't going to come into play unless there's standing water.

My sequence on kerdi is walls first with the edges brought to within 1/4" of the corners. Then kerdi band the corners down to the 2" below the level of the top of the corners. I would do the same with the floor and I would try to kerdi the floor after tiling the walls but if you have to kerdi first, make sure the kerdi is well protected.

You could pick up some keralastic to mix with your kerabond to set the bench tops. I would feel more comfortable with a modified thinset but if it's over kerdi you might want to stick with the kerabond. If you are going to use modified over kerdi I'd recommend versabond...seems to be only slightly modified.

By watching how long you cut the kerdi band for the corners you may be a ble to limit the amount of build-up, but it's the nature of the beast. When you are doing the corners hold them in place with your margin trowel and work the thinset out with a broad knife or drywall taping knife.


Bob V.
03-24-2008, 06:22 PM
Brian- I'm not quite sure what you mean by, Then kerdi band the corners down to the 2" below the level of the top of the corners. Is this to say that I should kerdiband all corners so that it stops short by 2 inches of the intersection of the 3 corners and then cover that with the Kereck prefabbed corners?

On the Schluter DIY videos that I've seen, they show that the keriband goes up first, then th Kerdi, and finally the corners. I guess it's just by preference. I'll check my Kerdi shower ebook and see what's described there.

Yesterday when I mixed up my first batch of thinset for the Ditra to plywood, it seemed too dry/stiff. The directions stated to mix 50 lbs of thinset with 5 quarts of water, so the first time I mixed 10 lbs using 1 quart,or 2 pints, of water. But the consistancy of the thinset did not seem to flow as I expected. So I mixed the next batch using 1 quart and then added a little more while mixing until it seemed almost too loose. After slaking, it seemed to have stiffened up. Then I mixed it again by hand, and spread it out using the 1/4 x 3/16 trowel. I was more satisfied with second batch, so the rest of the Ditra went better. Is this pretty typical of the method of mixing thinset for laying both Ditra and Kerdi? What about when mixing thinset to lay the tile? Should the thinset be stiiffer or fairly loose for tiling?

Brian in San Diego
03-24-2008, 08:17 PM

When we were at Schluter school in September (I want to go again) they recommended that the kerdi-band in the corners be done after the wall sheets were up. Reason: They said there was a shower or two that had leaked and the investigation of the failure found that the corners never got any kerdi-band! They reasoned that if the kerdi-band went up after the walls were covered then a quick visual inspection would verify that the corners had been kerdi-banded.

What I meant by the statemnet that is confusing eliminate build-up of kerdi material but still have your 2" overlap, you can stop your kerdi-band 2" below where the top of the preformed corners will be. Knowing how kerdi works and having showered in a kerdi shower for almost a year now I have come to the conclusion that the floor and corners are where attention to detail is important. Water doesn't get in my niche nor is there any water much above the 5' mark. If the wall intersections are kerdi-banded and the corners are taken care of then I think you will enjoy many years of showering without any problems.

I think you need to disregard the instructions for mixing thinset when applying Ditra or kerdi. Both require a bit looser mix to get the fleece properly imbedded. In the case of Ditra, if you are going over a plywood subfloor, you definitely want the thinset loose so the wood doesn't suck out all the moisture from the thinset before you've had a chance to imbed the fleece.

When you start laying tile you want to be closer to the manufacturer's recommendations. I go for a creamy peanut butter type of consistency.


Bob V.
03-26-2008, 04:10 PM
Brian- Thanks for the info on trying to reduce Kerdi buildup. I think I now understand what you meant regarding the length of the Kerdiband. Cutting it short so it does not go all the way into the corner, but still long enough so that the prefabbed Kereck corners cover it by 2 inches, would provide adequate overlap and still not have too many layers on top of one another. I'll also follow your advice on putting up the Kerdi sheets first, and agree on the "technique" of mixing thinset. Looser does seems better for Ditra and Kerdi. It appears that one should use the directions as guidelines, but for a rookie like me, I'm looking for foolproof rules. I guess that this is something that is more of a technique than I expected.

Any tips to share regarding Kerdi and outside corners? Can the Kerdi just go around a corner, or over a bench top? Or should it be two pieces with Kerdiband over this outside edge?

I plan on doing the mud floor after the walls and benches have their Kerdi and tiles. By doing it this way, is it correct to have the Kerdi that is on the walls, extend down to the shower plywood floor, and end up between the drywall and mud floor when it gets installed? Or should I figure out where the top of the mud floor will end up, and have the Kerdi stop short just above that? I think either would work, but my first example seems easier. The Kerdiband will cover the wall to floor seam either way, so which method is preferred?

Brian in San Diego
03-26-2008, 04:45 PM
I plan on doing the mud floor after the walls and benches have their Kerdi and tiles. By doing it this way, is it correct to have the Kerdi that is on the walls, extend down to the shower plywood floor, and end up between the drywall and mud floor when it gets installed?This method is quite acceptable.

I think outside corners are easy to "wrap" the kerdi around. I know I did it that way on the right side of my shower opening...just wrapped it around the corner onto the adjacent facing wall. I think I did the curb the same way...just wrapped it around the curb. Outside corners are a whole lot easier than inside corners.


Bob V.
04-24-2008, 08:37 PM
The Kerdi is installed on all the walls, benches and inside the niche, so now I have to put up the Kerdi-Band and Kereck. I'm still concerned about the added layers of Kerdi-Band where they meet at the intersections of two walls and the floor or top of the bench. Brian has had some good suggestions, but I have an idea that I'd like an opinion on.

Could I "miter" or cut the Kerdi-Band in a way that the 3 pieces all meet in the corner without overlapping, and then put the Inside Kereck over the joint? I think I would still get the desired 2" coverage from one plane to the other, and the Kereck would take care of any potential leaks right in the corner.

I have attached some pics of a mock-up. Let me know what you think.

Bob V.
04-25-2008, 06:07 PM

Brian in San Diego
04-26-2008, 12:20 AM

I think that would work but quite frankly I'd be a little nervous about it. It seems the vertical corner isn't getting the full 2" overlap by the pre-formed corner. I don't think the corner build up is as big a problem as some have made it out to be. I think if you cut your pieces carefully and apply them properly you should be o.k.


Bob V.
08-22-2008, 02:26 PM
It's been a while since I've posted, and the project had some down time, but thing are once again moving along. The Kerdie went up as planned, covering the whole shower area, including benches, and the shower tiling is about 85% done. I've got to the point where I need to focus on the niche area. The niche was kerdied in the same fashion as the rest of the shower, with Kerdiband covering all the seams and prefabbed corners for both the inside and outside corners. A lot of work is a small space. Since this is the first niche I've done, and the grout lines of the mosaic tiles that are around this area did not fall in the right place, I need some suggestion to make everything look right. The width of the niche is about 1/2" too wide to allow the grout line to fall exactly where I'd like it. If I cut the tile to fit the width of the niche, then just a sliver of a tile will be remaining. I dont mind losing 1/2", so how do I make the niche narrower after it has been fully waterproofed with kerdie? Can I just build up some thick thinset along one side over the kerdie? Can I use thinset to place a piece of CBU or Denshield in place and then tile over that? If I choose to do that, what are the long term shortcomings of CBU or Denshield not being under Kerdie? I've attached some pics to show some progress and further show my niche situation.

08-22-2008, 03:46 PM
I think you could thinset in a piece of half-inch CBU, Bob, but not DensShield or similar product. Needs to be something impervious to water on accounta it will be wet much of its life.

Be better to Kerdi it again after you pewt that piece, of course. That would even give you the opportunity to fix any questionable corners in that area. But the CBU alone would work fine, I think. :)

My opinion; worth price charged.

chuck stevenson
08-23-2008, 07:04 AM

Have you thought about putting a border around the niche using you accent tile?

Bob V.
09-15-2008, 03:57 PM
I took cx's advice and added a 1/2" piece of CBU to the side of the niche with thinset. All the tiles and grout lines line up nicely now. Thanks for the insight. I spent this last weekend attempting to create the sloped shower floor with deck mud. I now have a new appreciation for anyone doing mud work. What a workout! I needed a total of 450 lbs of topping mix and sand for the dry pack mortar for the 60" x 50" floor. Overall I'm pleased with 75% of the results. However, one corners is lower than I'd like, resulting in a lower pitch from the corner to the drain, and the perimeter of the floor is not at the same height all the way around.

Is there a recommended method of adding a thin layer of substrate to the new deck mud to correct my mistake using thinset or something else? I really don’t want to have to bust out the entire floor due to my lack of experience, and try again. But will if I have to. I don't want to look at this mistake for years, knowing I screwed it up. I could add the thinset, let it cure, then thinset the entire floor and add the Kerdi. Once that cured, then thinset and finally the tile.

My other thought was to bust out the floor, and use a Schluter pre-made 60" x 60" shower tray and cut it down to the proper dimension. I realize by going that route that the floor perimeter heights will be different on adjacent walls, but at least the slopes would be correct.

If I choose to bust out the floor, are there any recommendations on how to go about it without damaging the subfloor and walls. I’m guessing that I would use a concrete blade in a circular saw, set not too deep, and score the deck mud enough to break it into sections. The metal lath will be a problem, but I guess that just part of the rework…

09-15-2008, 04:06 PM
How much too low is your bad spot, Bob?

Bob V.
09-15-2008, 06:23 PM
The bad corner is about 3/16" too low. From the corner to center of drain is 36". I'd add 3/16 of thinset in the corner to make the perimeter level and then feather it down about 24" towards the drain. The "patch" would extend down each wall from the corner about 12".

09-15-2008, 06:35 PM
Yeah, you can fix that with thinset, Bob. Don't hesitate to do it in two passes if you're having trouble with smoothing the thick section. No points added for speed. :)

My opinion; worth price charged.

chuck stevenson
09-15-2008, 06:36 PM

You can use thinset but I like Henry floor patch. Sets in about 20 minutes and you can feather the edge.

Make or get a good set of straight edges to check for 'bird baths'.

09-15-2008, 06:42 PM
Quikrete Concrete Resurfacer would work well, too, if you happen to have a box opened. Or their Concrete Patch, which comes in smaller units. Or.......

Lotta stuff will work there.

Ain't never tried that Henry's stuff, though. Used a lotta other Henry stuff, mostly to fix roofs. Prolly not the same pookey. :rolleyes: