What to use to fill this in?

[mrblotto]

Hey hey everyone! Long time no visit. Was doing the 'hurry up and wait' song and dance for a vid card for almost a year....so there's that......

Anyhow, after over a year, we're finally tackling (or getting tackled by?) the fireplace. I'll include pics because they're better than words and such.
We're fixin to start attaching brickface (is that what it's called?) to the existing fireplace, but there's a noticeable 'gap'. I dont think slinging mortar in there is the way to go (because gravity, no wire mesh, whatever else) so I'm looking for possible solutions as what to use to 'level it up'
Any ideas out there in AT HG land? The fireplace is not going to be used (had it cleaned and then blocked off/plugged). It's just a wacky original pattern. I'll ask a visitor to look at it and ask them 'what's different about it?' Most look at it weird but can't figure it out. Maybe it was just
the style when it was made *shrugs*

TLDR;
-Original fireplace is fugly
-need something to level the sides before applying brickface
-what do?

 

[Mr.IncrediblyBored]

Why wouldn't mortar work? That gap is at most a quarter inch. It's not uncommon for folks to put a scratch coat of mortar over the whole thing anyway before applying the stone veneer. You could easily fill that in.

I like the brick though. I'd clean it up and leave it as-is. At most paint it a nice color.

 

[Greenman]

Thinset mortar is what you need to attach the thin brick, and it will easily fill the minor gaps you have.

Do yourself a favor and toss that plastic level in the trash. For that installation, I wouldn't use a level at all unless the existing fireplace is perfect.

 

[mrblotto]

Thinset it is then! Thx for the advice

 

[deadlyapp]

While you're doing the fireplace can you please make those two outlets the same height

Side note: You probably don't want to do more work, but if I was you, and that fireplace is no longer being used, I'd put an electric insert in there (or gas insert if you have gas nearby), then at least you have some functionality to the thing.