Granite 12x12 tile hearth installation [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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02-22-2008, 10:39 PM
I've purchased 20 12x12 granite tiles to use as a hearth & surround for my fireplace. There was previously a 1 1/4" solid slate hearth which I've removed.
The substrate is 3/4 in plywood flooring. Over the plywood & under the old slate stone is a shiny metallic covering extending 2' out from the wall. This has been nailed to the plywood substrate. I intend to leave this intact.

My prefab (yuk) fireplace is flush w/the wall, at the base of this metallic face is a row of vents for the blower & we don't want to block these so, this gives me approx. 1 1/4" of height to work with from the floor to the bottom edge of these vent openings. What my husband & I have come up w/is to create a concrete "slab" on which to place the granite tiles for the hearth. We thought of making it 3/4" thick--place approx 4 or more nails or screws into the floor within this 18" x 60" hearth area to keep this base from shifting. After this dries, we'll use a thin set mortar to set the granite tiles with and trim it out w/wood shoe moulding or quarter round to hide the 3/4" base & raw edges of the tiles. The tiles are not honed but I am going to buff them w/buffing pads on my Dremmel tool
Our questions are:
2: Is this an acceptable idea?

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Brad Denny
02-23-2008, 12:34 AM
Hello Sue,
You might need a few more posts before you can put up pics. How are you going to address the face of this mortar bed if it is going to be above the floor level?

02-23-2008, 05:02 AM
Thanks for replying Brad,

My picture didn't post because it said it was too large for the allotted space. I'll figure it out by the time I finish the project & post a before & after.

When u say the "face" of the mortar I'm figuring you mean the 3 sides that will hold the mortar in place? I thought of using boards like they do to pour a cement walk, 3 peices of wood, (1) 1" x 60" for the front edge & (2) 1" x 18" peices, 1 for each side. The 60" 's needed for the back edge would be the metal of the fireplace that the old slate hearth butted up against. My husband says the 1" is really a true 3/4" (which I'd forgotten from our past DIY framing projects, so, I figured that would be perfect to make my frame, check for level & fill it in, smooth it out. Also, I realized the tiles would be a hair more than the 18" x 60" which won't be a problem as our wood trim would hide any discrepancies.
FYI--I sound like a newbie, but to chalk up a list of my DIY projects, my husband & I have tiled a 9' x 13' master bath, installed a whirlpool tub,fiberglass shower, plumbed it, built the framing & installed all the walls for our bedroom/bath/office above our garage (30' x 24' area) ran the wiring & installed all of the electrical outlets, switches etc.
Also, I'm proud to report we finished our installation of the Schulter Ditra w/porcelain tile entry foyer project & it came out perfect. This last project is what led us to John Bridges web site & when we bought our Ditra our Home Depot didn't even stock it we had to order it---3 mos. later, they started stocking it!!!
Keep watching, because, our next projects are gutting 2 full bathrooms & tiling the shower & shower/tub area for each one, respectively. We've purchased John's book & are waiting for it to arrive, but I want to get started since it's a rainy weekend & I can't put up my new wood full surround mantel until I do the hearth & tile the face of the metal fireplace (we're debating wire mesh or hardibacker for this part. OK :blah: :topicoff: Sorry, I got carried away!!

Also, I'm wondering about the effect of the metal floor "flashing" (I guess you'd call it) affecting drying time for the concrete since I assume it would be non porous. Or, is this a non issue?
Thanx in advance if u decide to respond.

Brad Denny
02-23-2008, 06:56 AM
Sue, I was kinda thinking about the finished product. Are you going to put in hardwood around it to cover the change in height? Transition strip? You know, backerboard would be a whole lot easier unless you really need the thickness. I'm not particularly keen on the concrete idea, deck mud would be better if it was recessed, but maybe a dammed SLC pour would be best. Regardless, paper and lath should be used rather than the nails. I figure the flashing in your floor was installed to keep the heat away from something underneath. Oh, what type of joists do you have?? Here's a link to instructions for pic posting.

02-23-2008, 09:57 AM

I plan on trimming the 3 exposed sides w/hardwood trim. Thanks for the link to the pics & explanation.

I agree that cementboard would be easier, in fact, we glued 1/2" + 1/4" hardibacker together (our 1st mistake), the edges wouldn't lay flat so it wasn't level on the floor & hoping the weight of the tiles would help, didn't. So we opted for the idea of a pour. We're thinking we should go back to the hardibacker & mortar the 2 new peices together, then go with the paper & lath. Will update, hopefully w/photos.

Thanks for your input

Brad Denny
02-23-2008, 12:43 PM
While you into readin' stuff, Sue, try this link to get an idea of the SLC.

I'd go with that before laminating two pieces of CBU together. It's not intended for that. If it's not really out of level that bad you should put down ply and one layer of board. :)

03-08-2008, 07:25 PM
Hey All :wave:
Well, it's only taken me 3 wks to get cb ready for granite tile.
Hey Brad, I hope this works, we went against your good advice :sick: & used mortar to adhere the 1/2" & 1/4" hardibacker together to acheive 3/4" base for our granite tile, it's perfectly level!! We are praying this works.
Downloaded Irfanview, will try to post a "BEFORE" & an "IN PROGRESS", we hope there's an "AFTER" very very soon. Appreciate the granite tile cleaning advice. Doing that tomorrow (Sun.) still waiting for tile saw to come Will keep you posted!

Thankx, Sue