Hello everyone. I do alot of work as a sub contractor and it seems the product alot of flooring companies are using lately is Fiberrock. I personally like it better than the bs scratch coat method (never on my custom work btw), but at the same time find it awakward to work with and I dont know if its any good. I've gone to fix other guys work over Fiberrock and there seems to be no bond what so ever to the product. Could this be just a matter of poor workmanship, or the Fiberrock itself being the problem. Please discuss

I know exactly what you mean. I have seen tile come up from Fiberock with 100% coverage on the tile and being able to see the contours from the shape of the surface of the Fiberock and even the ink from the printing on the surface of the Fiberock in the thin-set on the back of the tile, yet it still did not bond. The flip side is that I have also tried taking tiles up from Fiberock and having to destroy the substrate to get the tile up.

Personally, I really think that it is the mix that you use. I like Fiberock and use it quite often - usually either Fiberock or Ditra. I have found that some of the lower end thin-sets, particularly if you let them slake for too long in the pail, have a hard time bonding to the Fiberock. I know that you are supposed to be able to use an unmodified mix, but I simply feel more confident with a good quality modified thin-set that starts out a little on the wet side (not too wet of-course) knowing that if it gets too dry it may not bond as well to the Fiberock.

Installing it, we always use thin-set and staples. The Ditra trowel is a nice notch for this.

Right now I'm using Laticrete modified thinset, and it seems to be doing well. But with other thinsets such as Ardex x3 I've seen what your talking about. The ink from the Fiberrock is literally on the back of the tile when you pull it up.

I've inquired a bit about this and from what I understand Fiberrock can have ZERO dust on the surface when installing tile takes place. I've been wetting an area with a damp sponge before back blading the thinset onto the Fiberrock. Weather this makes a difference or not remains to be seen, but it sure is a pain in the butt.

As far as un-mod thinset to install on Fiberrock goes, thats a new one to me.