Organic Fireplace Support

**Gunnar Alquist** · 09-08-2022, 03:38 PM

One of the districts where I inspect homes is an area that was used as a resort for the folks from San Francisco & Oakland in the early part of the 20th century. This was a hoppin' place where families would spend much of the summer hangning out, swimming in the river and dancing until late to the big-name swing bands of the 1930s that would come through.

But, residential construction was largely... creative, shall we say?

The first pic is a masonry fireplace in a home from that era. The second & third pics show the support for the masonry fireplace.

Don't you just love it?

Similar Threads:

**Jerry Peck** · 09-08-2022, 05:05 PM

That support looks like it may outlast the masonry fireplace.

**Gunnar Alquist** · 09-08-2022, 05:09 PM

Originally Posted by Jerry Peck

That support looks like it may outlast the masonry fireplace.

Jerry,

That is pretty much what I was thinking. A 200' tall, 7' diameter (at the base) coastal redwood weighs in at 50+ tons. A single-story masonry fireplace weighs-in at maybe 4-6 tons? Plenty of margin, the spread of the stump is more than I see for most fireplace footings, and this thing has been here for about 100 years now. But, I'm not sure that I want to guarantee it though.

I am hoping Bob Harper sees this and has a comment.

**Jerry Peck** · 09-08-2022, 06:13 PM

I would put it in the repor,, explain it's negatives, then point out that it's been there longer than the fireplace has been there.

Then recommend they get a qualified fireplace inspector to advise them of solutions.

Your photo reminded me of a deck support we had on our vacation house up here before we sold it: the deck had been there 30 years, supported by 4x4 posts, a tree had been planted at the edge of the deck.

After 30 years if tree growth, it broke a 4x4 post, pushed the post aside at an angle, and grew around the edge of the deck, fully wrapping and supporting the edge of the deck.

Our inspector wrote the broken post up as needing to be replaced.

Let's see ... a 3 foot diameter tree breaks a 4x4 post and is now supporting the deck, and ... that 4x4 post is needed? Really?

The inspector should have put it in the report as a 3 foot diameter tree has replaced a 4x4 post, which was in the tree's way, so the tree broke the 4x4 post and pushed it out of the way. Do so in a humorous way that Let's everyone understand that, with that 3 foot diameter tree holding the deck up, if that tree goes and takes the deck with it, one has A LOT more to worry about than that deck.

**Gunnar Alquist** · 09-08-2022, 08:26 PM

I forgot to mention. Evidently, two lenders have refused to lend on this home specifically because of the tree trunk supported fireplace.

Crazy, no?

**Jerry Peck** · 09-09-2022, 07:55 AM

One word: liability

Another word: fire

A third word: combustible

They aren't concerned with the support of the fireplace.

I wonder if that liquid applied fire-resistance/fire-proofing would work to solve that issue?

**Jerry Peck** · 09-09-2022, 08:41 AM

Maybe if they remove those wood 'form boards' (looks like concrete inside then through that opening), maybe that would solve the fire risk issue?

If not, then removing those form boards, temporarily supporting the fireplace, removing the concrete, removing the stump, then pouring a new concrete foundation footing (50 feet thick to make up for that stump

) should resolve the issue?

With all those wildfires around out there, I would think insurance companies would have greater concerns about insuring anything out there, that the issue for insurance wouldn't be that stump?

**david shapiro** · 09-09-2022, 11:50 AM

I wonder what a Field Evaluation Body would charge to label it. With their blessing, at least some insurers should give it a pass.

**Bob Harper** · 10-04-2022, 08:05 PM

Originally Posted by Gunnar Alquist

Jerry,

That is pretty much what I was thinking. A 200' tall, 7' diameter (at the base) coastal redwood weighs in at 50+ tons. A single-story masonry fireplace weighs-in at maybe 4-6 tons? Plenty of margin, the spread of the stump is more than I see for most fireplace footings, and this thing has been here for about 100 years now. But, I'm not sure that I want to guarantee it though.

I am hoping Bob Harper sees this and has a comment.

LOL. Thx Gunnar. Masonry fireplaces must have an independent masonry footing and foundation capable of supporting the full load of the fireplace and chimney. You cannot have any form of combustibles touching the underside of the fireplace for a 4" clearance. The hearth extension must be supported by the foundation or be cantilevered off it.

Easiest solution for me is to remove the fireplace to the subfloor level and replace with a factory built fireplace. You can do a woodburner listed to UL 127, a gas direct vent listed to ANSI Z21.88 or even a pellet stove. Believe it or not many pellet inserts are approved for built-in installation if meeting modest clearances to combustibles. I've built many cabinets over them.

Sorry I'm not always lurking here. In semi-retirement as technical adviser for a friend's fireplace shop in DE but ridiculously busy. I hope all are well.
Bob

**david shapiro** · 10-04-2022, 11:06 PM

Originally Posted by Jerry Peck

After 30 years if tree growth, it broke a 4x4 post, pushed the post aside at an angle, and grew around the edge of the deck, fully wrapping and supporting the edge of the deck.
, ..., if that tree goes and takes the deck with it, one has A LOT more to worry about than that deck.

The main reason to note your tree would be to say, keep an eye on things, because over time as the tree keeps growing it could shove the deck catterwompus, maybe tilt it off the supports for the other sides.

**Jerry Peck** · 10-05-2022, 05:30 AM

Originally Posted by david shapiro

The main reason to note your tree would be to say, keep an eye on things, because over time as the tree keeps growing it could shove the deck catterwompus, maybe tilt it off the supports for the other sides.

David, the way I've seen trees grow (versus tree roots) is that trees grow taller by growing up at their tops (base of tree doesn't grow up, doesn't push things up). And trees grow larger in diameter by adding more to their outside, growing around things and encapsulating things, not pushing things sideways.

The deck was straight, flat, and level, the tree had grown around the deck, holding it like a vice.

I remember seeing a cow pasture fence totally encapsulated by a tree, but still in line with the fence going out each side from the tree.

Tree roots under slabs, sidewalks, driveways, streets, yep, as the roots grow larger, those things are slowly pushed upward.

**david shapiro** · 10-05-2022, 07:20 AM

Thanks for the clarification, Jerry. You have a wonderfully broad range of knowledge. You're right in thinking I was extrapolating from what I've seen the roots do.

**Gunnar Alquist** · 10-05-2022, 05:06 PM

And trees grow larger in diameter by adding more to their outside, growing around things and encapsulating things, not pushing things sideways.The deck was straight, flat, and level, the tree had grown around the deck, holding it like a vice.

That may well be the case, but I suspect it isn't going to do the tree any good. My understanding is the phloum, cambium, and sapwood are the living/growing parts of the tree trunk. It seems to me that a tree that is completely encircled with a deck could be significantly damaged if it is completely encircled and choked-off.

Originally Posted by Jerry Peck

Tree roots under slabs, sidewalks, driveways, streets, yep, as the roots grow larger, those things are slowly pushed upward.

Indeed. I see lots of failing decks and patios in the same area because of trees and the damage (albeit slowly) they can do.

**Jerry Peck** · 10-05-2022, 06:13 PM

Originally Posted by Gunnar Alquist

It seems to me that a tree that is completely encircled with a deck could be significantly damaged if it is completely encircled and choked-off.

Aye ... but ... you are referring to 'the deck' encircling the tree.

I was referring to the tree growing around and encapsulating/encircling a portion of the deck., or in the case of the fence I mentioned, the tree completely grew around and encapsulated the wire pasture fencing. It appeared that, originally, the fence was installed next to a relatively small tree, then over the years, as the grew in size (height and diameter) the tree grew around the fence, healed itself, and at the time I saw it, there was a fence 'going through' the tree, quessing that 1/3 of the tree was on the side of the fence I was standing on, and the other 3/4 of the tree was on the other side of the fence.

You are correct in that when one wraps a rope/wire/whatever around a tree, as the tree grows, it will grow around and encapsulate that 'band', and that 'band' will likely damage the tree, and could even eventually kill the tree.

Years ago I read stuff on the proper way to attach framing to a live tree for a treehouse, and just as importantly, how "not" to attach the framing to the tree. And the most important way (with regard for the tree) to "not" attach the framing to the tree is to wrap or 'pinch' the tree between framing on opposite sides of the tree. The preferred way was to through bolt all the way through the tree, the tree will heal itself around the bolt.

Nowadays, they make special bolts for attaching framing to trees as they have learned how to best protect the tree from injury and damage before the tree can heal itself (which takes a lot of time). I've never used those special bolts as I haven't built a treehouse in a very long time, but the last time I looked up "the how to do it", those special bolts are EXPENSIVE. And special brackets are now made to fit on those bolts to allow the trees to move in the wind without tearing the framing apart (the brackets slide on the bolts to allow for tree movement perpendicular to (to/from) the framing; and the brackets slide on the bolts to allow for tree movement parallel with the framing; combine the movement of the brackets on the tree in those two directions and they allow for all angles of tree movement related to the treehouse framing.

Sorry ... got a bit long winded on that treehouse framing ...

**Bob Harper** · 10-06-2022, 04:28 PM

Either the foundation meets the code, or it does not. Not only does this fail by a mile to meet the code but it fails as combustibles are under the firebox. You cannot make anything I'm aware of into meeting ASTM E-136 as "non-combustible" therefore, treatments, which coat the surface, such as reducing flame spread, are not recognized and not the same thing. An ASTM E-84 flame spread rating is referenced to red oak in a 25 foot Steiner Tunnel test. The time it takes red oak to burn the 25 LF is referenced as 100. If your material is rated at, let's say 25, that means it burns 25% as fast as red oak....BUT IT STILL BURNS!

That stump may seem solid as a rock on the date of inspection. Chances are WDI's or rot will set in one day. Do you want your daughter and grandkids living in that house when the firebox settles?

What if the stump just pyrolyzes until weakened where it bears? Suddenly, the chimney collapses killing your grandkids. Seriously? Not worth it and definitely not insurable. I doubt you could get a termite letter on it, either.

There is no justifiable reason to take a chance on this. You are bringing fire deliberately into a structure. That, ordinarily, is nuts. The only reasonable way we do that is by abiding by codes and standards to achieve some reasonable degree of risk of harm. I'd love to be sitting in the courtroom when Dale Feb testifies, they built a fire on top of an old tree stump.