Do I need expansion joints?

[Paul Denison]

I'm a newby with tile (stone) so I will have lots of questions. Thanks in advance for your time.

Basically, I have a porch (8 x 23) with the 8 foot section running into a family room (20x 20), all this over concrete (about 550 sf). To picture this, it looks like a hatchet with an enlarged head. I have purchased DITRA for this project.

1) Do I need a joint and how do I keep it from ruining my pattern (versailles)? I plan on using sill seal on the perimiter and a 1/4 grout joint (stone has chisled edges).

I read the Schluter site and they recommend unmodified morter under ceramics, but don't mention stone which should breath.

2) Can I use modified for the DITRA to concrete and also for DITRA to travertine?

The stone is rough polished (rustico - not a smooth surface) and is 8x8, 8x16, 16x16 and 16x24.

3) My wife wants the holes filled in the stone so I have been experimenting on grout colors. I think I will grout without sealer and seal afterwards unless you guys have better ideas. I like some of the defect showing in the stone and don't want to cover it all up, but I have lost this battle. She is afraid that the tile will become black with dirt in the pits, which I have seen myself in porcelain on the show room floors. The stone is beautiful and I don't want to ruin it. I noticed that the sanded grout (Mapei) seem to polish the stone a little.

Fire away!

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[Davy]

Hi Paul, welcome. I'd say 1 joint would be enough, 2 would be better. It's gonna break up the pattern, can't hardly keep that from happening. The stone will breathe some, marble and granite mix could be used. I'd give it an extra day or two before grouting or walking on it if you can.

I think you'll find that you actually won the battle when it comes to grouting. It's easier to fill in the holes than to try to keep all the grout out. She is right though, fill them with grout or they will get full of dirt.

I seal very little before grouting, others seal all their stone before grouting. Just down't get ahead of yourself. Spread a little at a time til you get the hang of it. :)

[cx]

Welcome, Paul. :)

What Davy said.

The requirement for exterior installations is a movement joint every 8 - 12 feet in each direction.

You must also honor any expansion/control joints in the concrete slab.

Schluter would want un-modified thinset for all of your application, including bonding the Ditra to the slab.

My opinion; worth price charged.