unmodified vs modified

[MannyG]

Hello,

I'm remodeling to bath rooms using marble tile over Kerdi on hardibacker (1/4"flrs - 1/2"walls). The shower flrs are also Schluter kits. I have already purchased unmodified thinset with my tile order. The kerdi was an after thought. I chose Schluter products because of everything that I've read on this forum and from others. Should I use unmod for the kerdi application and is it ok to use the mod for the tiling? Please advise.

MannyG

[jadnashua]

I'm pretty sure they specify modified to hold it down to the plywood subflooring, and unmodified to hold the tile onto it. John B uses Versabond on both sides. The stone may call for something else...one of the pros that does this all the time will fill you in. I used Custom's granite and marble medium set to put up granite over Kerdi and it seemed to work well. The granite I used changes color when it is wet. It took nearly a week for the color to change back to "normal" after thinsetting them onto the Kerdi, but they are solid. Wouldn't want to have to take one off!

[Steven Hauser]

Hi Manny,

modified under the kerdi and unmodified over the kerdi. This is per Schluter. Don't use the cheap unmodified, use the premium dry set.

[trecile]

Why are you using hardibacker? Schluter specifies Kerdi over plain ole drywall. Cheaper and easier to put up. Also easier to apply Kerdi to drywall than hardibacker.

[bbcamp]

Terri, there was a change of plans after the backerboard was installed.

[MannyG]

It's a welcome releif whan you get such a quick response, thanks to all. HB is already insatlled so thats were I'm working from (thanks Terri). I called D. Taylor and he advised using unmod "Masrter Blend" (Home Depot) or "KeraBond" (Lowes).

I've got time so I'm not rushing it.

MannyG

[John Bridge]

Manny,

Keep the thin set very loose, almost but not quite runny. Dampen the Hardi-backer with a sponge prior to spreading the thin set. Hardi has a tendency to steal the moisture from the thin set if you don't give it a bit of water. Not wet, now. Just damp.

[MannyG]

Well this past weekend I went ahead and applied the Kerdi to the shower stall walls, used TEC Full Flex mod TS. So far it looks like I have a winner. It set up real nice, looks good. Thanks Steven/John, I took your rcommendations "modified under Kerdi/mixed loose". I'm ready to start the tiling will use Master Blend unmod, found it at HD reasonably priced for 50lbs. For the send bathroom I'm just going to put the Kerdi right over the dry wall.

MannyG

[MannyG]

This site is just chuck full of info. Gotta love it.

Well I know its been a while, but I'm one of those weekend warriors when it comes to tiling at home. So here is the latest.

MannyG

[rstreet]

Manny,

Looking good. That kerdi is fun to install isnt it? I know what you mean about the weekend I've been going at mine for two months.

Interesting concept to use the remaining kerdi tray on top of the bench.

Randy

[MannyG]

Guys, Gals I have turned the corner on this project, I am ready to start tiling.

Here are some more pics...

MannyG

[MannyG]

Thanks rstreet,

Wastenot want not. I also used cindar bricks/concrete for the curb, and under the bench to give 18" h on the bench. Only had to go two high with the bricks for the curb (14 bricks), the shower 32x60. Used Mason Mix for the bench and curb.

MannyG

[Bluecat6]

I see in the pictures the Kerdi felt laid down prior to drain install. Should the Kerdi be over the large flange of the drain assembly?

I am about to embark on a similar project and have been reading these excellent forums and Tile Your World for the last week.

Thanks

[MannyG]

Large flange then Kerdi over it. Go to Schluter.com and watch the video, it will help. the kit comes with the dvd.

MannyG

[trecile]

If you look at the pictures it looks like there is one picture of the Kerdi lying on the floor BEFORE the drain is installed, but the Kerdi doesn't look like it has been adhered with the thinset yet. The 2 pictures above that show the Kerdi adhered to the floor with the drain below.