Floor and wall tile question

metamel · 07-19-2006, 09:04 PM

The adhesive was MasterBlend which was mixed as prescribed with water, but no acylic and no custom-flex stuff was used as mentioned on the bag for stronger bonds. The grout was put in the cracks and let dry for a day, so I'm not sure about any cleaning that you mention. I noticed that some of the tile (13 x13 in) are somewhat loose with small wiggles on a corner, but the surrounding area is stable. Somebody else did the screwing of the CBU to plywood, and I think that not enough screws were used. Maybe I should put another 1/4-inch CBU on top of the existing 1/4-in CBU and screw it down with 3-in spacings, and then try to hit the joists or not hit the joists, depending on whether or not the joists should be hit.

metamel · 07-19-2006, 09:08 PM

How much does the membrane add to the tile elevation over and above what it is now without the membrane? Maybe I could just put the membrane over the CBU and redo the tile and hope that it will work. What about adding another layer of wood over the CBU? Removing the CBU would be a lot of work, which I would to avoid if possible. Does 1/4-inch plywood add much to the strength or do I have to go 1/2 inch? Thanks, Metamel

R&D Tile · 07-19-2006, 09:13 PM

Let's try this one more time, that floor needs to come up as well as the CBU if it was installed incorrectly, NOTHING you do to it or put over it will help, not going to write a book on why at this point.

Floorwizard · 07-19-2006, 11:31 PM

I am really liking those questions FM

metamel · 07-20-2006, 12:41 AM

Well, there are sections of the floor, mostly where nobody walks, that have un-cracked grout. So it's not a simple thing as installed correctly or un-correctly, a binary state. I look at it as the areas under changing stress, such as walking, need some firming up. So let's say the whole problem was caused by not enough screws in the CBU to plywood floor. Then it would be a relatively simple fix to add more screws in the walking areas, and then, perhaps, also add an acrylic to the thinset for stronger bond, and, lastly, use a chaulk for the grout, so that any small movements would bend instead of crack. However, I'd like to not do the chaulk instead of grout thing, because I would have to take up all of the other good grout and redo it. If there weren't enough screws in the CBU, then why take it up and do it all over, when it's much simple to just add more screws. metamel

R&D Tile · 07-20-2006, 07:18 AM

Quote:

Originally Posted by metamel

Well, there are sections of the floor, mostly where nobody walks, that have un-cracked grout. So it's not a simple thing as installed correctly or un-correctly, a binary state. I look at it as the areas under changing stress, such as walking, need some firming up. So let's say the whole problem was caused by not enough screws in the CBU to plywood floor. Then it would be a relatively simple fix to add more screws in the walking areas, and then, perhaps, also add an acrylic to the thinset for stronger bond, and, lastly, use a chaulk for the grout, so that any small movements would bend instead of crack. However, I'd like to not do the chaulk instead of grout thing, because I would have to take up all of the other good grout and redo it. If there weren't enough screws in the CBU, then why take it up and do it all over, when it's much simple to just add more screws. metamel

Boy oh boy, you CAN NOT add more screws, it won't do a thing, for one if there is no thinset under the boards, that's one issue, if there is and you screw through it, it will cause more voids, FORGET about caulk for grouting the joints, modified thinset will only help with the bond to the substrate, it will NOT help strengthen the floor and keep it from failing, small movements that bend?, are you kidding, tile and grout don't bend, there are no quick easy fixes, it HAS to come up and be installed correctly, do you want to know how, not a problem, OR you can do it your way and have to go through all of this again real soon, sorry to be so blunt, but your not listening to the real issues here.

metamel · 07-20-2006, 02:35 PM

R&D Tile: Thanks for the response. Essentially, you're saying that thinset is needed between the plywood and CBU, so if it's not there, then I have to start all over. So the minimum fix that you forsee is that I take up the CBU, add a thinset and 1/2-inch CBU, and then do as a before with the tile laying. Would it do any good to strengthen the thinset for either the plywood top or CBU top? The whold idea of the chaulky grout is that it would bend, supposedly, so small movements don't fracture it like a regular hard grout. However, you're saying forget about the chaulky grout, right? Do you thing the above will work, as I don't see adding a 1/2-inch extra layer of plywood, because the floor would be too high relative to other floors, etc.