What kind of slate do you have? Do you know the country of origin (or even have a picture/web site)?

Some slates are better than others and knowing where yours is from, would help a lot in determining whether you will have issues or not.

Trish,

As Stonegirl stated, there are differences in quality and kinds of slate. My parents had a huge front entry done in slate, and all six of us girls and accompanying dogs/cats/friends/husbands/babies/toddlers etc trampled through there for twenty years (and I think it was at least 10 years old when they bought it). It was very smooth (as I recall) and not at all like the Indian type of slates I'm seeing a lot of now. There weren't any problems that I was aware of, and certainly no shaling.

It was a house originally built by an architect in an authentic Early American style (IF Early Americans had 5000 sq ft houses! :>), so I am guessing it may have been some type of Amercian sourced slate?

Tricia, there was a good thread on this a while ago. It's linked below. May be helpful in seeing experience and pix of what others have done, particularly those with slate.

HTH,
Eliz

Here is a link that might be useful: Slate/Travertine thread

tricia have you posted somewhere already whether this is on a concrete slab or on a wooden subfloor? If wood, have you done the math, to ensure your floor's expected normal deflection is below the range allowable for stone? Porcelain can put up with more deflection, btw.

I installed slate in our bathroom after looking at the slate look-a-likes, including Dal-Tile. This was my second tile installation in a bathroom. We chose China gold ungauged-- each tile was quite different in thickness. We decided on slate because we didn't like the look of the look-a-likes. The floor installation was very time consuming because you have to set each time and make sure each tile is at the same finished height. I think the 8x9 bathroom floor took me about 16 hours (6"x6" slate). So I could see why an installer would prefer to use ceramic or porcelain.

We bought 15% extra--some tiles fall apart when cutting. We then sealed it well and we have had no problems with it (3 months now). I think it is stunning and I'm so glad we didn't choose look-a-like.

I suspect if you went with gauged tile, then it would be easier to install. Good luck.

The slate is china rust multicolor. We also got a sample of brazilian slate, which I thought was a bit more flaky, so we decided against it. May have just been the tile I saw, however.

It's a wooden subfloor, and the installer said it was acceptable condition for stone.

It is not just the condition of the sub floor that comes into play here. You need a minimum deflection of L/720 for natural stone (this has to do with how much weight the joists will carry before bending - BillV would be much better able to explain this) and then also 1.25" thick combination of plywood underlayment, with a tile backer (like Hardi Backer) or a membrane like Ditra on top of that.

The Hardi or Ditra will have no structural value, but will act as separation membrane (and in the case of the Ditra, also as moisture barrier). With a stone installation it is also preferable to have a moisture barrier in there, so Ditra would be the better product, unless your tile guy prefers a roll-on membrane like Redguard or something.

The Indian slate probably is not a very good stone as far as using on a fairly heavy traffic floor either. It is much softer than the Brazilian Multicolor (or it should be!).

If you have your heart set on slate in there, pick a stone that is hard, dense and fully metamorphosed. If you like the rusty multicolor ones, Brazilian or African slates probably would be better.

Also - a sealer that will give it a gloss or satin "wet look" is a bad idea for use on a floor, since this is a topical product that a) will wear off in traffic patterns and b) will impede moisture migration through the stone and could lead to some nasty side effects like spalling in lesser quality stones.

I installed a very rough slate floor in a sunroom. It was a bit flakey at first because it WAS rough stuff, but that didn't last. I liked it. It wasn't sealed, but cat poop, mud, and long-standing water didn't hurt it.

Don't worry.It'll be great!

I also used a multi-color slate in my entry. I don't really know where it is from....assumed India. Lots of pieces broke apart when I sorted them. It was a mess. The tile dealer warned me I'd have a shedding problem for quite a while and I just expected to be vacuuming a lot. Truth is, after six months here, I have had nary a problem. And my wood floors are soft, so believe me, if the slate were shedding I'd be freaking out!

I had their best guy do the install. The pieces were all a different thickness, but he did a great job.

The Indian slate probably is not a very good stone as far as using on a fairly heavy traffic floor either. It is much softer than the Brazilian Multicolor (or it should be!).

I agree. I was very surprised to see the reply where the Brazilian slate was flakier. Usually it's the other way around, in a big way. The Asian slates are notorious for shaling. One way or the other, with ANY slate, all the shaling that's going to occur, WILL occur within the first 2-3 months. After that, it's not a problem. Also, both David and Stonegirl borught up a valid point about deflection. Most woodframe homes are engineered to meet the minimum deflection standard for ceramic tile (which also happens to be the minimum for MOST flooring), which is L/360. What that means is the length of the joists in inches, divided by 360. If you were to put a stringline across the floor it would be the curvature that occurs when a 300 pound weight is placed in the center of the span. If it's more than the result of that L/360 equation, then your floor's too weak for tile. Fortunately, as I said, most floors are engineered to meet that standard. The problem is that natural stone require the floor to be literally twice as stiff, as Stonegirl mentioned. The satandard jumps to L/720, and usually that'll mean bracing the joists from below or "sistering" them with new joists. If you don't do thins, there's a better than average chance that you'll have problems with the floor later.