Replacing Loose Floor Tiles

The house was built in '05 and we purchased in '09. In the master bath, there were some loose grout lines at the time and two tiles directly in front of the heat vent (and directly below the window) were loose. While we have certainly gained some additional loose grout since then, I can't say it has been much. The issue now is to finally get around to replacing the loose tiles.

My initial thought was that they simply let the mortar dry too long before laying the tiles down as there is zero adhesion to the tile backs. My second thought was that it dried too much due to location in front of the vent when the heat was on. (It may have been finished in late fall '04.) Now, having started removing grout I find a few additional loose tiles. Won't guess if they were just held in by the grout or I popped them loosed while removing the grout. But, I am leaning back toward they just let it dry too long because these tiles also show zero adhesion.

For a longer term, permanent fix, I am sure the subflooring needs to be improved. For now, can I just re-lay these specific tiles somehow? Is it possible to chip away the old mortar off the backer board? Cut away and replace the section of backer board?

 

How many times do you want to redo this?
First thing I'd do is figure out what's below the tile.
Under sized, over spanned joist?
Backer not installed in a bed of morter.
Tile is a one shot deal.

 

What size are the tiles? If over 8x8" then it is not recommended to use mastic, which is premixed mortar from a tub instead of a mix of mortar from a dry powder. When you remove the grout and expose the adhesive underneath, is it rock solid or does it have some give to it, like pushing a knife into a rubber gasket? Preliminary questions as we need to investigate what went wrong. Cracked grout, as Joe mentioned, usually is a subfloor issue related to over spanned undersized joists or insufficient subfloor thickness. Bare with us as we investigate your situation.

 

The tiles are 11-3/4 inch square. The photo, assuming it sizes well enough, shows two tile backs and the bed they came out of. I assume they should not be so clean. My need right now is just to get them back in place for a few months while we plan a more permanent fix. Timing for a full on project does not work at all right now.

I have read enough recent posts to recognize that the subfloor is insufficient for tile and this is the only area in the house that has it. We have tile and backer on 3/4 OSB on 2x10 joists at just under 14 foot span. We experience a lot of bounce throughout the house in general. This bathroom is on an outside corner, if that adds any support.

I can't tell if the backer was placed on mortar or not. I don't see any showing around the vent cutout and I get some movement where I can get a fingertip under it. Given the other shortcuts we have found in the house, I would guess there is mortar there, just not complete coverage.

 

Using a hammer and a 3" wide stiff putty knife as a chisel, remove the old mortar down to the backer board, just hit across the trowel lines and it should pop off. May take some effort, but you may get lucky and it releases as easy as the tiles did. Without seeing the mortar first hand, it is tough to tell why here was no grab or coverage transferred to the tile itself. To reset the tiles , get a bag of modified thinset. Mix up small batches, back butter each individual tile with a 1/4" notched trowel, set the tiles in place and give them a wiggle to help set the mortar to the backerboard so that you get good coverage. The idea of a notched trowel, is that when you wiggle the tile into place, it collapses the mortar in the voids for better coverage and bond.

 

Just take it easy with the removal, it will come up but if you are doing a repair you dont want to make it bigger than needed,

When I did my bathroom I popped up all the tiles, they were not back buttered, and with a thin putty knife I could easily scrape away the mortar off the cement board.

 

Thanks for the advice. Kinda sounds like the idea of removing the original mortar is not as far out as I had feared. I definitely will have to work more carefully going forward. While checking, I found two additional tiles that "crunch" slightly with weight on them. It has been my observation that every job takes three times longer than expected, five times if I've never done it before.

Unfortunately, the wife wants to change the grout color, so it seems I will be at this for some time. At least that can be done in easy stages, right?

Back butter is in addition to the layer on the backer board, not in place of, right? I assume this is to ensure complete, direct contact with the tile? The original layer of mortar was definitely uneven, had gaps, but it seems very solid on the backer board. Will see tonight how easily it comes off.

 

You clean the existing mortar completely off. Back butter is that you spread the mortar on the back of the tile, pull trowel grooves on the back of the tiles and then place on the floor with a twisting motion to set the mortar. You do not trowel the floor and then trowel the tile, it is one or the other. Back butter approach helps when you have to replace individual tiles and it would be a mess to try to trowel into an 11x11 space.

Changing grout color will be best left to when you look for the more perm. solution to your problem and rip all this stuff out. For a short term fix, stay with the same color, unless you are fond of opening up other cans of worms.