Fireplace Hearth

[JohnL509]

We purchased a 1950s home last year and have been working our way through updating it. Decided to try to tackle replacing the tile on the fireplace hearth in anticipation of converting to a gas fireplace insert in the near future.

I was able to remove the tile today but the mortar bed (I think that's the right term) was not in as good a condition as I was hoping. Large chunks of it came out with the tile in one area and there are other cracks and divots as well. I removed all the loose pieces but stopped short of pulling it all out to do some more research.

There appears to be some type of brick/stone slab beneath the mortar bed. My understanding is that patching and leveling the existing bed is not a long-term solution as the new tile will be prone to cracking.

Is my only way forward to remove what remains of the mortar bed and replace it with a new one? Any other suggestions on a plan to finish out this project?

Thanks for any and all help!

[cx]

Welcome, John.

The only fix I would recommend there would be to remove the remainder of the mortar bed and replace it with another. Shouldn't be difficult to remove what's left and that also gives you the opportunity to create a new bed of exactly the correct height to accommodate your new tiles.

It's not a difficult procedure, 'specially in a small area such as that. And even if it takes more than one try to get it right, the materials are dirt cheap and the DIY labor's free, eh?

My opinion; worth price charged.

[JohnL509]

Thanks!

A new mortar bed appears to be the way to go. I'm sure I'll have some more, but my two immediate questions are...

1. What's the best mix to use for the new bed? I'm seeing bags of 4-1 Mud Bed Mix or Deck Mud as possible options, as well as talk of custom mixing your own. Any suggestions for a DIY with minimal experience?

2. I could be wrong, but it looks like the original mortar bed goes into the firebox and at some point maybe something was put on top of it to smooth or fill cracks. Regardless it's in pretty rough shape. (pics attached) Should I be ripping out what's in the firebox and making that part of the replacement effort as well? Or just worry about where I'll be tiling. It won't ever be used as woodburning fireplace again, so my only real concern is preparing the firebox for a gas insert.

[cx]

1. You want a 5 to 1, sand to Portland cement mix for your deck mud. If you'll look in the Shower Construction thread in our Liberry, you'll find various ways to achieve such a mix. You could also use one of the proprietary mixes, such as the MAPEI 4 to 1 mix you mentioned, but I think you'll find a plain sand/cement mix with no additives easier to work with exactly what you want for your mortar bed.

2. If you can ensure the firebox will never again see a wood fire, the mortar bed will be fine in that area, too. I think what you currently have must have been a mix using fire clay for it to have held up under wood burning conditions.

My opinion; worth price charged.