Hearth tile cracking

[Adios Pantalones]

Folks that have installed tile over plywood/cement board/other R rating boosting materials:

have you had problems with tiles cracking?
Is this due to uneven load bearing (more weight on one stove foot)?
Were the tiles fairly thin?
If the tile were say a full 1/2" thick- do you think that would solve the problem?

I assume that flat, inflexible substrate under the tile is pretty key

edit: full disclosure- I don't have cracking hearth tile but have heard the complaint before. I'm contemplating making tile, so am asking in order to gather experiences on this.

 

[begreen]

From the little experience I have, the key is not the tile thickness, it's having a rigid substrate underneath. A 1/2" tile can crack if the substrate is not solid and something heavy is placed on top of it. If the floor is slightly uneven, I'd use a thicker plywood (like 5/4 plywood), insulation board, 1/2" cement board, then tile. If the floor is really uneven, it will need to be shimmed and leveled under the plywood. Otherwise the plywood may eventually sag and try to conform to the irregularities.

 

[Adios Pantalones]

It sounds like even with heavy substrate, there's a potential for sagging. This is my worry- even if I made awesome heavy duty tile- I'd get blamed for cracking if the install has dips etc. in the substrate pieces.

 

[Jags]

I even if I made awesome heavy duty tile- I'd get blamed for cracking if the install has dips etc. in the substrate pieces.

I know that I would blame you! :coolsmile:

Solid substrate is the key to ANY tiling job. Without it - it doesn't matter WHAT kind of tile you apply, the ~100 pounds per square inch that is being applied to a very limited "zone" for a stove install is gonna crack it.

 

[CarbonNeutral]

I have 1/2" concrete board mortared and screwed into the sub floor. The front two legs sit on this, the back two on the concrete fireplace slab with tiles over. We walk on it as well year round. No cracking after 1 year.

 

[FWWARDEN]

Built my raised, tiled hearth with 2x6 stringers every 12". Top sheathed in the thickest plywood I could find, followed by two layers of 1/2" concrete board that were both mortared together and screwed down like a bastard. I also put cross members between the stringers for lateral stability. 3 years worth of 24/7 burning during the season, kids and dogs walking all over the hearth year round, and not a cracked tile or grout line to be found.