Resurfacing a raised hearth without a subfloor

[dave11]

This hearth was built in 1951 and covered with thick marble slabs. Eventually they cracked and loosened in places, and I recently removed them. Beneath them was a heavy slab of concrete and metal lath, which I also removed.

The first pic shows the current layout. There is 1x lumber spanning the top of the raised hearth, but there's no subfloor beneath them. You can see between them right into the basement below.

The second pic shows a view from the basement looking up at the left side of the hearth from below. Again, no subfloor. There is no ledger board joining the hearth to the masonry. Instead, you can see short 2x4s standing to the right, they stand on a ledge made of brick built into the masonry there. To the left, the 2x4s are nailed into the sides of the first floor joist.

The framing of the hearth seems solid enough, at least to stand on.

I'm curious if anyone here has seen this before, or if anyone thinks it should be altered before the hearth is re-covered. Also looking for suggestions on best substrate for hearth before tiling, cbu/wood/mortar etc. to make up the large distance between the top of the framing and the floor of the firebox. There's 3.25 inches between the top of the rectangular framing of the hearth, and the floor of the firebox.

Thanks.

 

[bholler]

You need to take all of that wood out and pour a slab. You are not alowed to have any combustible material incontact with the bottom of your hearth extension. it also needs to be tied back into the body of the fireplace with rebar.

 

[dave11]

The fireplace has been perm altered for a gas insert and can no longer burn wood. The damper is out and the warning placard is in. The hearth ext is purely decorative.

 

[bholler]

The fireplace has been perm altered for a gas insert and can no longer burn wood. The damper is out and the warning placard is in. The hearth ext is purely decorative.

It should still be done right. Read the installation instructions for the gas insert I am sure it says it needs to go into a fireplace that was capable of burning wood. I think with a gas insert the risk is low but what if the next person pulls the insert and converts back to wood?

 

[dave11]

Actually since I'm not demo'ing the fireplace or it's framing, it is grandfathered into the code. I'm not going to tear down anything and rebuild it on the tiny chance someone in the future will ignore common sense and the warning placard and try to build a fire in a fireplace with a closed off flue containing two stainless vent pipes. Even if they got a fire going, such fires haven't burned down the house in the past 66 years.

My question is about the suitability of the pedestal for tiling, because the original marble had cracked/loosened in places, and whether anyone here has seen this sort of pedestal before, and how they handled it.

 

[bholler]

Actually since I'm not demo'ing the fireplace or it's framing, it is grandfathered into the code.

No it isn't you have done enough work that it is no longer grandfathered in sorry. I do this for a living in pa and I can gaurantee you that with the ammont of work you are doing on the hearth extension it need to be brought up to modern code

I'm not going to tear down anything and rebuild it on the tiny chance someone in the future will ignore common sense and the warning placard and try to build a fire in a fireplace with a closed off flue containing two stainless vent pipes. Even if they got a fire going, such fires haven't burned down the house in the past 66 years.

Yes but they might take those liners out and fix the damper so it would again be suitable for burning wood. And they would assume that because the insert requires a wood burning fire place that your fireplace would be able to burn wood. As far as not burning the house down in 66 years have you ever heard of pyrolisis?

whether anyone here has seen this sort of pedestal before, and how they handled it.

Yes I have seen them and I have torn them out and replaced them with a proper hearth extension.

 

[dave11]

No it isn't you have done enough work that it is no longer grandfathered in sorry. I do this for a living in pa and I can gaurantee you that with the ammont of work you are doing on the hearth extension it need to be brought up to modern code


Yes but they might take those liners out and fix the damper so it would again be suitable for burning wood. And they would assume that because the insert requires a wood burning fire place that your fireplace would be able to burn wood. As far as not burning the house down in 66 years have you ever heard of pyrolisis?


Yes I have seen them and I have torn them out and replaced them with a proper hearth extension.

You obviously have an excess of free time and an odd itch to scratch. I do not, so this is my last reply to you, just in case someone else reading this one day thinks you have it straight.

The building inspector here has already told me that this doesn't need to be changed because I'm just resurfacing and because the fireplace is no longer considered wood-burning. I'm sure you know better than he does though.

I'm out of here.

 

[bholler]

You obviously have an excess of free time and an odd itch to scratch. I do not, so this is my last reply to you, just in case someone else reading this one day thinks you have it straight.

The building inspector here has already told me that this doesn't need to be changed because I'm just resurfacing and because the fireplace is no longer considered wood-burning. I'm sure you know better than he does though.

I'm out of here.

Well sadly if he said that then yes i do. The big difference is i am liable for any inspections i do building inspectors in pa have no liability at all. Did he even look at the instructions for the insert? If you didnt want to hear how to do it right then why did you ask for advice?