Best way to remove old tile, backer board and all?

[gpm1976]

The room I've decided to tile already has an existing tile floor. I thought the tile would come up easier, but the first few tiles didn't come up very easily. Getting these tiles up are not my main concern. I'm more concerned with how to get the old backer board and screws up without totally destroying the subfloor... or am I just going to have to get the sawsall out and remove the subfloor and screws like that and just replace it all?

If I do have to remove the subfloor, can I cut it back all the way to the walls and replace the sections that span the room? If I do that, what's the best way to brace the edges.. 2x4?

[Kman]

This is one of those jobs where you really hope the original installer took many shortcuts and did a crappy job, thereby making your job easier.

Unfortunately, the best way I've found to take up tile and backer board is with a prybar and hammer. Remove a tile or two, then start working the prybar under the backer. As you pry up, use the claw of the hammer or a second prybar a few inches away to start pulling up a larger section. With most backers, the screws/nails will pull through and the backer will come loose.

It's not likely to come up in big sheets, but rather in one or two foot squares, if not smaller. I did 55 square feet over hardibacker a couple of weeks ago and it took about two hours to get it all pulled up, the nails pulled, and everything hauled out. The installer didn't use thinset under the backer, but used construction adhesive instead. I used a chisel to scrape the glue off.

If yours has thinset under the backer, you might try scraping it off. If that doesn't work, or if it seems like it's going to be a nightmare, you might be better off replacing the subfloor altogether.

[gpm1976]

Thanks for the reply, Kman.

I think I need to get rid of the subfloor. I cut a hole in it, and it's 3/4" particleboard over top of 1/2" OSB. I don't see any water damage, but I don't see the particle board coming up nicely either.

The big problem I see is that it looks like the screws holding down the backer board run right along each joist. I can't back the screws out because the heads are filled with thinset. Any harm in ripping up the floor then using a sawsall to cut the screws off?

[cx]

This the same floor where you didn't use thinset under the CBU, Greg?

If you elect to rip up the floor without removing the fasteners, I'd recommend an angle grinder with a very thin abrasive cut-off disk rather than a Sawzall for cutting off the fasteners. You'll find some of the CBU screws are just gonna smirk at your Sawzall blades. The abrasive disks, on the other hand, will do a splendid job of removing them. Do wear appropriate protective gear.

My opinion; worth price charged.

[Bodie Powers]

Greg, no problem doing that. If drywall screws were used, you might be better off removing all of the CBU and snapping off the screws with a hammer....common DW screws are very hard and not easily cut with a sawzall blade, however they're also very brittle and will easily snap off with a blow or 2 from a hammer.

[gpm1976]

This is actually a different room with older tile. I'm just planning on doing this one the right way.

For that matter, I removed the tile in the back entry way and it was sitting on just 1/4" ply. It was there for almost 20 years and not a sign of cracked grout or tile. How is it that there are zero issues with a method like this that from what I've read on here is completely wrong? What did they do differently that made this tile hold up for this long?