Hi Oliver,
I'm no pro, but I'm an avid Landlord that likes to do my own work. Many of the things that I'm suggesting are because I myself learned the hard way by overlooking the "not so obvious" myself. But also consider that I might also be missing something that a Pro knows, because they deal with Tile every single day while I'm only dealing with it a few weekends every year.
3/4" subfloor + 1/2" Fiber-rock should be more than enough. But, make sure you've spread thinset between the subfloor and the fiberock. This is to ensure that the voids are filled. When you're dealing with tile (which is a very hard material), you need a perfectly flat surface to tile on, if there are any voids, there will be movement, and when there is movement, your tile will eventually crack.
As for buttering your tiles, there shouldn't be a need for it. Most folks that back-butter are only back-buttering because they don't trust the thinset adhesive and they believe that more is better. But more isn't better, it's just "squishier" and more messy. Just make sure you're using the correct sized trowel. Floor trowels spread out more adhesive because you'll need it for the traffic on the floor, wall trowels spread less because there is far less foot traffic.
There's no need for thickset because you're dealing with little tiles. Thinset will be just fine.
As for spacers, they're for creating a uniform grouting space between your tiles. Use as many as you feel is necessary to maintain your spacing, there's absolutely no harm in going overboard with spacers. They're little and very cheap to come by.
To help you keep your tiles level (little or no lippage) you might consider using the QEP LASH system, or the Tuscan Leveling System. Although it's not absolutely necessary, they will give the DIY some piece of mind and it will help you create a Tile Project you can be proud of in the end. |