Tiling Stairs - use flexbond?

I am wrapping a staircase with slate tile - treads, risers, and the nosing on the treads.

I have reinforced the stair structure with screws and ring shank nails.

I have applied 1/4" Fiberock (new product from USG) with thinset and numerous galvanized ring shank nails.

I have mesh taped and mortared the joints of the Fiberock (I see some recommend that this be done in the same step as laying the tile but it just wasn't to be on this project)

My plan of attach is to install the nosing first, then the treads (to overlap the nosing perfectly), then the risers.

Only question - should I think about using the Flexbond crack prevention mortar to attach the tile? Reason being this would allow for a little movement which is inevitable in a wood structure staircase. The staircase is solid, but I know there may still be a little movement.

(FYI I plan to grout the joints BUT the joint between the treads and risers I am going to put silicone caulk instead because I feel this is the most likely area that the deflection of the staircase might pop the grout joint)

Thoughts?

"should I think about using the Flexbond crack prevention mortar to attach the tile? Should I think about using the Flexbond crack prevention mortar to attach the tile?"

What type of tile is it:ceramic,porcelin, granite, marble etc?

I hope you embedded the backboard into a bed of thin set mortar before you nailed the sheets down. As any voids in the areas where people walk will cause the tile to compress and likely crack.

Hey Dog,

Is it past your bedtime or what? Steve already gave the answers to your questions.

I still think tile (and in this case slate) on wooden steps is a high failure installation. Maybe if you had added some plywood, but still you're likely to see more cracks than you'd like within the next 6 months or so.

Jaz

Steve I too think you are asking for big trouble. Tiling entire wood-structured staircases is very problematic. Using slate (of all things) to do so is even more troublesome. Especially if it is the bargain basement slate from Home Depot or one of the other big box importers of slate from China.

If you "know there may still be a little movement" as you have stated then you are in fact wasting your money and time on this one.

FlexBond is an OK modified thinset but it isn't anything fantastic, you should be looking at MegaFlex maybe if you insist on moving forward with this project.

Thanks Jaz - good eye.

It's not a cheap flakey slat - it's a blue montauk tile and seems to be very high quality

I know that this is a little risky but I have seen it done in my neighborhood and it seems to have held up well. My only question is, other than recommending for me to stop the project altogether, what's the best mortar for the job (that might allow a little flexing)? Is MegaFlex available at Lowes?

Take it Jaz!

MegaFlex is a product of Custom Building Products and is available via special order from Home Depot. It would also be available from any "real" tile store.

Lowe's will have something comparable but I'm not familiar with their line these days.

Lowes should have Mapei Ultra Flex 2 ($20 per bag). I personally am A big fan of Mapei products. As for using nails with the fiber rock, I always use screws when installing any kind of underlayment. I have torn out hardibacker before that was nailed down and it came out way too easy. As for the general idea of tiling a staircase, If the staircase is solid (no squeaks/movement) and you use a high end modified thinset mortar over properly secured hardibacker (fiber rock), the Installation should stand the test of time. I have tiled several staircases over the years and have never been called back for anything more than a grout touchup. However I have always used 1/2 Hardibacker and screwed it down.

Steve: I am very interested in how your project turns out, and how it fares after a couple months or so of wear. I also want to tile my stairs. What is the strongest tile available for this project? For me it is the stairs to the lower level of the house. Thanks for posting!

Just for anyone paying attention - - -

Mapei Ultraflex II in no way compares to Custom's Mega Flex, no way. Those two products are on opposite ends of the spectrum from one another.

I'm not comparing manufacturer's because Mapei will have a product comparable to Mega Flex but I promise you Ultraflex II is not it. That suggestion is merely inexperience talking.