installing granite for fireplace surround

[bc]

I am using 12x12x3/8" granite tiles to build a fireplace surround and hearth.  What product should be used to install the tiles to the wall and also to the floor (cement) for the hearth?

[Mark D.]

Let's break this down into two parts for you. First, the floor is the easier install. You can use just about any thinset to adhere it to the floor. You did not tell me how big a grout joint you are using, but let's say it is 1/8" thick. I would use spacers to keep all the joints the same size and as you set them make sure you are keeping all the tiles level and on the same plane. Use a square notched trowel for this application, floating the floor with thinset and buttering the back of each tile.

For the vertical, I need to know what you are adhering it to - is the fireplace brick? Is it stucco? Generally speaking you can use spacers and either mastic or thinset, but with the thinset I would set no more than 3 courses in height each day as if you put a wall up 9 tiles tall the weight can make the bottom courses buckle or lose their bond with the thinset. The trowel of choice for this application is a 'V' notch trowel.

With either of these once the mortar has fully dried (overnight) you can pull out the spacers and grout with a nonsanded grout colored to your preference. Before you grout I would seal the granite with a stone sealer like Hydrex by Tenax. this protects the stone from getting etched by acids as well as making it stainproof, but the big plus for you is that the sealer will act like a grout release also.

If you have any other questions let me know. I hope you find this helpful.

Mark

[bc]

The granite tiles will adhere to a sheetrock wall.  Does this make a difference in the application?  I had planned to use 1/8" spacers.  Thanks for your help.  bc

[Mark D.]

Ummmm...Some people would go right over the sheetrock, but I think that is a bad idea, what my Mom would have told me was "penny wise & dollar foolish". A couple of reasons why are that you won't get a solid bond with the drywall, and even if you did the weight of the thinset and tile would rip the bond away from the sheetrock unless your wall is graded away from vertical, which is unlikely.

A better idea would be to get a cementuous product like Wonderboard and screw it in over the drywall according to code. Wonderboard, Hardibacker, whatever as long as it is a fiber-cement product. After you install that the thinset (or mastic) will bond easily enough to it, and the board has strength so it's not going to tear off like sheetrock would.

You can get materials like Wonderboard at any Lowe's or Home Depot...while you are in there check out how expensive their diamond blades are and then call me to save money. By the way, those cementuous boards cut easily with a turbo diamond blade that goes on your Sklisaw.

Mark

[bc]

Thanks for the tip.  I did have some reservations myself about the sheetrock supporting the weight of the granite.  But let me ask you about a product I saw on your website called Instant Install Epoxy.  Would this work better than thinset or mastic for the wall application?  And could it also be used for the joints instead of grout?  If so, even if I use thinset for the floor could the epoxy be used in those joints?  I am thinking of reducing the size of the joints to 1/16" or even abutting the tiles (my wife likes the look of a solid piece of granite).  If the tiles are abutted (or is this a bad idea?) is there a need for anything in the seams?  Again, thanks for your help.  bc

[Mark D.]

If you butt the tiles together there is still a slight bevel on each tile that will cause the appearance of a joint. Do not use epoxy for this install. If you want stone with no grout lines you need to use a slab, not tiles. Also, if all the tiles are not exactly the same size you will have gaps anyways. You can try it but I cannot recommend it.

Mark