Flooring Tile - How much mortar?

hi everyone

After doing about quarter of the tiling I decided to come and ask the pros before we really screw things up.

We're tiling over cork, and the tiles keep coming up uneven. Partly due to the floor having dips in some places (2nd floor condo, concrete floors) and partly because we used too much mortar probably or too little.

When I use the trowel at 40 degrees I can see the cork protruding from between the trowel lines. Is that normal or should the mortar go thicker so when I run the trowel the cork underneath isn't seen?!

We're using a 1/4 x 3/8 x 1/4 trowel

Thanks much

I am not sure I understand your application. You applied a cork underlayment and hope to apply ceramic, grouted tile over it?

right
we have cork as underlayment, it's required by the HOA to deaden from walking etc. So we have concrete, glued cork underlayment, mortar then tile.

So I want to know if the mortar should go on thick or if we should see some of the cork underlayment showing between the trowel lines?

I am lost myself. are you sure that the cork isn't just required for laminate or wood floors? I have never heard of laying tile over cork. Honestly it sounds like it couldn't possibly work. You want an extremely rigid underlayment for tile such as cementboard thinsetted to the subfloor. If there is a sponge effect I would think they would not adhere or keep from cracking. Also you talk about "mortar" mortar by definition is a heavily sanded portland mix most commonly used between brick and block walls. You should be using a modified thinset. 1/4"X3/8" Trowel is ok for flat ceramic tile. Please post back and tell us where you heard to put cork under tile. That is a new one to me.

Someone I know lives in a high-rise and they were required by the home owner's association to put down cork before laying tile.

The cork comes in a roll and isn't very thick at all, I think 1/4. 2 years later their tile hasn't moved, and that's with a 3 year old boy who rides a bike and a car toy back and forth in the livng room.

What I can't figure out is if the cork underlayment should portrude from between the trowel lines or not. To me it seems like it's too little thinset mortar having only trowel lines

no that's fine you just don't want it to stick up past where you will put your grout. After you lay a tile and move it around a little like your supposed to do. Pick one up with your margin trowel (if you don't have one get one) and see how much thinset is sticking to the tile. If it is spotty you might want to use a different trowel or method. The lines between the tiles are normal they just haven't been spread by any pressure like you have under the tiles. I still have a hard time understanding putting tile down on cork. Sorry but it makes absolutely no sense to me. I hope it comes out alright for you. Good luck!

great
Thanks a lot :)

I have never used cork as an underlayment before but apparantly it is acceptable. The cork needs to be 1/2" and must be over a concrete slab at least 6" thick. Additionally tile size must be at least 12" x 12" and epoxy grout must be used. It doesnt sound like it would work but apparantly it does.:)

He did say he was going over a slab. Still weird to me and I can't see an advantage to it. Must be one I am just not aware of. Epoxy grout? oh fun stuff!

Im also missing the point here. I dont see what advantage the cork would provide over a slab.:)

Im also missing the point here. I dont see what advantage the cork would provide over a slab.:)Me either as hard as I try. However I think of several distinct disadvantages

Here is a cork underlayment product I came across that is designed to be used with tile. Maybe this is something like what he is using.

http://www.tileprotection.com/product.php?productid=87&cat=63&page=1

-Parke