Combustibles in hearth extenstion with fireplace mounted stove

[asteiger]

Recent avid reader, first time poster.

I moved to new house last year, midcentury-ish colonial (if thats a thing) in NJ, built 1950. It has a nice looking but small fireplace. I had it inspected last winter and they pretty much said nope, you can't use this without rebuilding it. Problems found were chimney lining issues, wood forms left underneath the firebox hearth (under 12" brick/masonry), and floor joists built into masonry of the hearth extension, which also likely run underneath the face brick of the fireplace.

I think i can remove the forms via the outdoor cleanout door, but the joists are going nowhere. as of the two that are in there, one spans a supporting length. The other (closest to firebox) I see no reason it should have been there in the first place.

The closest joist to the firebox is about 6" off the opening. The extension is concrete, which contains the joists, with a layer of brick on top (assuming ~2" thick). The brick sits flush with the hardwood floor. Firebox opening is 27"h x 34"w in the front.

I thought I could maybe install a Jotul F100 fully into the firebox (only thing I've found that would fit) since it has only non-combustible floor clearance requirement, no R-value. But when the installer saw the joists he said he wouldn't do it. The stove would also be a pretty tight fit. I know I wouldn't get a ton of heat out of it, I just want to have something (anything) without having to completely rebuild the chimney.

So my question is. Why is this not ok given the floor requirement? Would heat from the side of the stove conduct down through the side brick and into the lower bricks, thereby heating the wood?

I've mostly resigned myself to the fact that I have a solely decorative fireplace that I can only burn candles in but part of me just keeps thinking... really? Plus the fact that I have the opportunity to purchase a secondhand unused F100 from someone.

 

[asteiger]

I also can't tell how/where exactly that cast iron pipe runs without cutting a hole in the wall above the face brick. The pipe is waste drainage from the second floor bathroom, which sits roughly right above the fireplace. It almost seems like the chimney is built around the pipe.

 

[jetsam]

Either get an insert or build the hearth out. Jamming a freestander into a fireplace is a real waste, as a lot of the heat ends up outdoors.

An insert bypasses the above concerns

A hearth extension and a rear venting freestander also takes care of things because you can build the new hearth on top of the existing hearth and floor, and honor all required insulation values and clearances.

The existing hearth is too shallow for practical use anyway!

The f100-in-the-fireplace plan gets you a tiny stove with short burntimes and crippled heat output due to its installation.

I'd personally be thinking about a hearth extension and a much larger rear venting freestander if there is room, and a hearth extension and a semiflush insert if there is not.

As far as joists under the hearth bricks... you just need to honor all of the stove's clearances. I don't see why the setup you described is a problem, if all clearances are met.

 

[asteiger]

Thanks for your reply. I don't think I can do an insert due to thickness of the extension. Basically, the constructions does not meet NFPA 211 section 11.3. I believe all wood and gas inserts require NFPA 211 compliance when installing into a masonry fireplace.

 

[asteiger]

I pretty much expect I wouldn't get heat out of the tiny stove. But I wouldn't mind having a pretty fire to look at. As it stands, I have a fancy looking pile of useless bricks in my living room.

 

[bholler]

Either get an insert or build the hearth out. Jamming a freestander into a fireplace is a real waste, as a lot of the heat ends up outdoors.

An insert bypasses the above concerns

A hearth extension and a rear venting freestander also takes care of things because you can build the new hearth on top of the existing hearth and floor, and honor all required insulation values and clearances.

The existing hearth is too shallow for practical use anyway!

The f100-in-the-fireplace plan gets you a tiny stove with short burntimes and crippled heat output due to its installation.

I'd personally be thinking about a hearth extension and a much larger rear venting freestander if there is room, and a hearth extension and a semiflush insert if there is not.

As far as joists under the hearth bricks... you just need to honor all of the stove's clearances. I don't see why the setup you described is a problem, if all clearances are met.

An insert absolutely does not negate these concerns. They are designed to be placed in a code compliant fireplace with the proper completely non-combustible floor. This is not what he has.

 

[bholler]

I pretty much expect I wouldn't get heat out of the tiny stove. But I wouldn't mind having a pretty fire to look at. As it stands, I have a fancy looking pile of useless bricks in my living room.

Any stove with an ember protection only hearth requirement will be fine assuming it meets all other clearance requirements

 

[asteiger]

Any stove with an ember protection only hearth requirement will be fine assuming it meets all other clearance requirements

So the stove would only have about 7" of side clearance to the edge of the firebox at the farthest part in the front, which would taper back to about 2" in the back. The stone is obviously not an issue, but I have no idea how thick it is before it hits wood.

 

[bholler]

So the stove would only have about 7" of side clearance to the edge of the firebox at the farthest part in the front, which would taper back to about 2" in the back. The stone is obviously not an issue, but I have no idea how thick it is before it hits wood.

The only way to know if the side walls are the proper thickness is by drilling a few test holes.

 

[supremeastra]

Have you looked to see if you can find a zero clearance high efficiency fireplace insert that would fit? Maybe something like this? https://www.supremem.com/fusion_18.php

 

[bholler]

Have you looked to see if you can find a zero clearance high efficiency fireplace insert that would fit? Maybe something like this? https://www.supremem.com/fusion_18.php

That is just a regular insert meant to go in a code compliant fireplace

 

[asteiger]

Huh, yeah. The manual does state only non-combustible hearth, but it also states code compliant masonry fireplace.

 

[bholler]

Huh, yeah. The manual does state only non-combustible hearth, but it also states code compliant masonry fireplace.

Non combustible hearth and ember protection only are not the same

 

[Nigel459]

Non combustible hearth and ember protection only are not the same

What’s the diff? Specified r value? I’m putting in a stove that states “Ensure you protect combustible flooring with a covering of noncombustible material.” Does this mean the same as ember protection only?
It also states no r value required so I think that may me the crux of it, just looking for confirmation and elaboration on your statement.

 

[asteiger]

Non combustible hearth and ember protection only are not the same

That makes sense. All the different manuals lay out their specs in different ways. Unfortunate that there isn’t a standard way to list specifications, clearances, etc. that all manuals must follow.

 

[begreen]

A freestanding stove with a blockoff plate and a blower can do a decent job of heating.

What are the fireplace dimensions with the door assembly removed?

 

[asteiger]

A freestanding stove with a blockoff plate and a blower can do a decent job of heating.

What are the fireplace dimensions with the door assembly removed?

The opening is 34”w x 26.5”h

 

[supremeastra]

That is just a regular insert meant to go in a code compliant fireplace

Yeah, looks like it will still have the same issue. You could put up a couple lally columns for support, cut out the offending joist then fill in the void with new concrete and another support.

 

[begreen]

The opening is 34”w x 26.5”h

The F602CB might just squeak in there. If the hearth needs extending, it can be a sheet of metal or simple protector.