Need help on fireplace tile install

[dborns]

First off, great site! I'll be using it quite a bit on all the projects we have planned on our home.
One of the projects on our new home is removing the old granite tile around the fireplace to update to new. I started by breaking out the tile on the hearth, and found a 2" mortar bed under it, that was on top of cinder blocks that spanned the hearth. On each end, there's about 7" of mortar poured in to fill the complete hearth. I'm wondering if they didn't have a way to cut a cinder block to fill the shorter span on each end, so they just filled it in with concrete. Now with everything removed down to the blocks, I have about a 2" depth that I need to refill to get the tile flush with the wood on the hearth. When I go to lay new tile, what's the best underlayment to put down to fill that 2"? Can I put a couple sheets of concrete board down, with mortar in between each along with screwing them to the cinder blocks?
As you can see in the first pic, there was tile around the outside of the front of the fireplace, then approx. 4" of oak trim on each side, and about 14" of plywood above. I've removed all of that back to the cinder blocks of the chimney. That leaves about a 3/4" gap between the back of the column and the wall cinder block. What's the best way to install tile on the wall portion? Again, I had thought of mortar/ screwing concrete board to the cinder blocks and installing the tile over that? That would make the wall flat, and would also fill the gap between the end of the column, and the cinder block where the oak trim was.

Sorry if that's not a good explanation, but maybe the pics will help. Thank you.

 

[Snoonyb]

The mortar in-fill was more than likely the shortest distance between two places.

I'd pour the hearth because any foot traffic can cause flexing.

On the vertical, screwing a substrate will cause a reveal at the fire box that will need to be addressed, so does your new feature have a method of coping with that reveal.

 

[dborns]

"The mortar in-fill was more than likely the shortest distance between two places. I'd pour the hearth because any foot traffic can cause flexing."

So when you say pour it, does that mean going back to a mortar bed?

I did not think about the edge of the concrete board showing at the fireplace opening; thanks for mentioning that. What if I cut the concrete board a little shy of the fire box opening, and then use mortar and span from the fireplace brick to the edge of the tile? That would cover that reveal, and we could then paint it black to match the inside of the firebox, (which the previous owners had painted the inside bricks).
That is basically what they did at the back of the hearth where it meets the firebox because the fire box is the same height as the cinder blocks, and the front of the hearth is almost 2" taller, so they used mortar to slope up from the bottom of the fire box to the top of the tile.

I'll also add, in case it means anything, we plan on never moving again, and we don't plan on ever using this fireplace to burn. Unfortunately, when we have used it, the house actually got colder.... It's an older home, so there are some gaps to address somewhere. So, it's basically just going to be for looks.

 

[Snoonyb]

Exactly.
There are add mixes that will color the mortar.
The fireplace should not draw it's combustion air from inside the dwelling, so if you address that, add a glass encl. and a heat-a-lator, the fireplace can be made functional.

 

[dborns]

Yeah we came from a new home with a zero clearance gas fireplace that would run you out of the room, so when we fired this one up and just got cold, it was a downer. I had a chimney company come over to check/ clean the flue, but he said it looked like it had never been used it was so clean.
The idea of an insert was shot down when my wife learned it would cover quite a bit of the designer tile we ordered, so we may never use it.


So build the wall out with concrete board with mortar and screws, making sure it’s plumb and flat, then install tile. Mortar bed on the hearth.

Thank you for the suggestions.

 

[Snoonyb]

Rather than an insert you could core drill the existing firebox and duct to fresh air, for the combustion air.

 

[slownsteady]

We don't have any masons show up regularly, and outside of general advice i don't think our usual crowd would be expert enough for this kind of project. If Stadry shows up, he might have some ideas. may be best in this case to consult a local expert...might be worth the money.