[jessica9405]

Hello all,
I am in the process of ripping up old ugly carpet in my home & replacing with porcelain tile (foyer, hall & dining room - @ 350 sq ft). I've had 4 contractors over to quote the job & am getting mixed answers. The sub-floor is cheap particle board (not plywood). 3 of the 4 contractors say we need to put down cement board first and 1 of the 4 says we need to use that wire mesh stuff under the tile. The 1 that suggest the mesh speaks very little English & came in with the cheapest quote....leaving me a little apprehensive. I have no idea what the best method is. Can anyone out there help?

Thanks much! Jessica

 

[Bud Cline]

The "wire mesh" procedure is strongly advised against by the entire mainstream tile industry. It has a very high failure rate and it is one of the cheaper methods. Anyone doing it in that fashion is not current on acceptable methods, get rid of him immediately.

The backerboard is one of the better ways to go but there is still a lot more to the process than deciding between backeboard and some hack-method using wire mesh. All cement boards MUST BE installed in a fresh bed of thinset mortar. The moisture in the mortar alone can be enough to trigger an expansion of the partical board.

Unfortunately (for you) partical board is also poo-poohed. A tile installation is no place for any type of partical board anywhere in the mix. Simply adding cement board over it doesn't change anything. Partical board will expand and swell under certain moisture conditions (and atmospheric changes) and take the tile installation with it wrecking everything. I guess if your insurance is paid you would have some recourse. Tile certainly cannot be applied directly to partical board.

 

[jessica9405]

Thanks for the reply Bud. Gives me more to think about. I didn't realize cement backer board was laid w/ morter. I thought it was glued & screwed to particle board (or whatever subfloor material), then the thinset is laid for the tile to adhere to. Guess I need to learn more before doing anything....

Thanks again

 

[Bud Cline]

All makers of ceramic tile backerboards want their product installed in a fresh bed of thinset mortar (in some cases unmodified thinset mortar), this is without exception.

This procedure is to eliminate any voids that would be created when the boards are fastened to the substrate. Thinset mortar is THE ONLY ACCEPTABLE form of adhesive. And even then it is not intended to adhere the boards but instead it is intended to fill the voids. The fasteners are what is to hold the board to the substrate. If your proposals don't include this method then your installers need to update their procedures. This method has been in existence for a very long time. Don't allow anyone to install your backerboard in any other fashion and don't except any excuses. The chosen tile is then also set with thinset mortar.

Partical board when exposed to moisture has the ability to expand to twice its original thickness while absorbing the moisture. In the event of a flooding situation this can happen quickly (overnight). In an intermittent environment of high humidity or moisture from another source it can take much longer but it still happens.

In some cases a slight expansion would/could go unnoticed but if rigid tile is involved the damage will be extensive and unrepairable. No professional knowledgeable tile installer will allow partical board to be present in his installation process.:no:

 

[bjbatlanta]

The mere act of putting the thinset on particle board to attach the cement board COULD cause swelling/separation problems. Not my field of expertise, but I would say the particle board needs to be replaced with plywood unless there is some sort of "membrane" installed to prevent (guarantee) the particle board isn't exposed to moisture. As Bud stated, it doesn't take much to totally ruin your new floor. Water can seep in through the grout if it isn't sealed properly or a fair sized "spill"/accident near a wall where it can get under the baseboard and penetrate to the particle board. When in doubt, go to the mfgr.'s web site for the tile you are going to use. They will have an outline for the proper installation procedure and the proper substrate necessary to keep your warranty valid. I'm sure someone more knowlegeble (in the trade) will reply......

 

[Bud Cline]

unless there is some sort of "membrane" installed to prevent (guarantee) the particle board isn't exposed to moisture.

All available membranes pose the same issue. They all require a moisture-laden adhesive application. The partical board can not be used.

Water can seep in through the grout if it isn't sealed properly

No grout can be sealed enough to insure against water/moisture migration. It just doesn't work like that. Grout sealers ARE NOT waterproofing products. They are simply stain retarders.

 

[Bud Cline]

I'm sure someone more knowlegeble (in the trade) will reply......

Should I be offended at that remark?

WHAT!!! My knowledge isn't good enough?

 

[bjbatlanta]

Sorry, Bud. I meant someone more knowlegable than ME would answer as to the use of a membrane and whether that in fact would work. And you did....

 

[Bud Cline]

:wallbash::laughing: