FirePlace in a Cave

[grottoman]

Hello all-

I didn't even know how to search for this in the forum (i.e., what terms?? cave??); sorry if it's already been discussed but I suspect not.
I found lots of references to 'man caves', but those are typically artificial converted garages and such.

I have a much more serious man cave. It's an actual cave; a unique location known as 'the Cave'. A large rock bluff, underneath which is on the left a free standing cabin, then a big open space, then a small structure (3 walls plus rock ceiling and 4th wall of rock) that is my 'VIP / Bar / Lounge' I'm putting together.

The cabin is free standing, but 90% of it is below the rock overhang. The front 10% or so is where the chimney from the wood fireplace (brick / mortar, old style) goes up 'in front' of the cave entrance.

You can see some pictures at
gogrotto.org

but attached is a wide view of the situation.

The cabin is on the left. The Bar structure is on the right.

My question is specifically around the Bar.
It is a three walled structure with a door, but not a fully enclosed space (i.e., there are gaps in certain places that will remain / are ok).
I'm about to put in walls and floor (i.e., decorative, beyond the existing substrates).
In the winter, I'd like to have heat in this structure.
My thought is to put in a small (loft size, for instance) wood burning fireplace.
In the picture attached, it would be on the outside wall of the Bar, facing into the room.
If I installed it 'flush' with the existing wall, it seems to me that it could have a chimney or something that takes the smoke out the front of the cave, high enough that it would continue up the rock face rather than come back into the cave.

My questions are things like
-is this a crazy idea? how crazy?
-would I have to cut all the nearby trees down that are up above that area?
-is there a screen / spark guard option that would make it safe?
-could I use some sort of stovepipe rather than a chimney with a fireplace? (I've thought of the woodstove but it would have to 'stick out' into the room, I think, and isn't the same as a fireplace).

I'm in an area where expertise and knowledge around codes and unusual installs is about nil, which is good and bad... I could probably disguise the fireplace as a still and nobody would give it a second thought.

But I want to avoid setting the neighborhood on fire.

So please feel free to ask followups in the course of providing what I'm sure will be respectful honest guidance, without the need to simply slam my idea and questions as moronic.

I mean, cut me some slack; people have been burning fires in this cave long before I got here. So is it that crazy to think I could add a fireplace right outside the cave?

Ha!

Thanks in advance for any helpful feedback.

 

[grottoman]

And an additional picture of the 'outside' of the Bar, with the rock cliff above it.

The fireplace 'rear' would be just to the right of these existing windows (which will likely come out).
So a full chimney seems like overkill, whereas maybe a 5-8 foot section of pipe or chimney would get the smoke going right up the rock face (but there is vegetation and such above there).

Thanks for feedback.

 

[Doc C]

A few thoughts come to mind.

1. What happens when you have an inversion?
2. Why would the 3/2/10 rule not apply? And since i think it will apply, how can you get your pipe to meet the requirements?


That is a cool place by the way!

 

[moresnow]

Sweet looking place! One question. Alabama + cave=SNAKES Aaaaaarrrrrgggggghhhhh

Maybe I am wrong altogether? Surely one of the resident pro's here will chime in on your situation.

 

[EatenByLimestone]

I'd start with the location you want a fire in if it was just a cave. That's not the entrance. I'm sure the main reason is you don't want to be trapped by the fire should things get a lot more exciting than intended.

 

[grottoman]

A few thoughts come to mind.

Thanks to all the respondents so far.
Have only seen a few snakes in over ten years, I think the slab floor maybe isn't to their liking.

Regarding the 3 2 10 rule, if I understand it correctly, I think the salient points are:
The fireplace will technically be outside the structure, with the chimney or pipe running straight up the rock face itself.

Regarding safe exit, the ceiling is rock, and there are only three walls to burn, so I don't see that as a big issue.

My main concerns are the sparks coming up the dace of the rock and perhaps catching a tree / vegetation, and whether I could get a prebuilt fireplace and some sort of metal prebuilt pipe or chimney rather than build a chimney, for instance. Although I suppose I could do a brick chimney that has three sides,the fourth being the rock that's already there...

Thanks for thoughta



1. What happens when you have an inversion?
2. Why would the 3/2/10 rule not apply? And since i think it will apply, how can you get your pipe to meet the requirements?


That is a cool place by the way!

 

[jatoxico]

Seems like the bar is recessed pretty far into the cave. Don't know if you could get a chimney to draft with the long horizontal run that looks like would be needed. If you did move forward I think you would need stove pipe and would have to be aware of clearances to vegetation. Definitely presents unique challenges.

Considering the stone will suck up heat up, the lack of local stds and the other aspects this may be good time for a rocket mass heater but can't tell if you have the room for the masonry bench or similar structure that's needed.

 

[grottoman]

Seems like the bar is recessed pretty far into the cave. Don't know if you could get a chimney to draft with the long horizontal run that looks like would be needed. If you did move forward I think you would need stove pipe and would have to be aware of clearances to vegetation. Definitely presents unique challenges.

Considering the stone will suck up heat up, the lack of local stds and the other aspects this may be good time for a rocket mass heater but can't tell if you have the room for the masonry bench or similar structure that's needed.

Thank you!
Actually, though, the fireplace will almost be outside the rock, with almost no horizontal run needed at all...
It would be all the way to the right of the two windows, where that round wooden tabletop is leaning, roughly...
So from there, it would at most be a fot or two to get out to the face of the rock and then up.

I think a wood stove with a regular wood stove pipe with just a slight angle to or a slight elbow would be fine.

But I'm hoping to have a regular fireplace instead. Not sure if I can somehow get a prefab exhaust for such a fireplace or not..

 

[skw]

A couple of thoughts from a total newbie:

1) Yes, you can vent a fireplace to a prefabricated metal chimney. People in new houses do that all the time.
2) From a code perspective, the "structure" is probably the built man-made part not the whole cave. So for code you probably only "have to" get the chimney away from there.
3) From a drafting & venting perspective, the cave and the trees do matter. You probably need to get up at least 3 feet above the ground over the cave.

It would probably be easiest to fasten the chimney pipe to the stone of the cave, and run it out and up.

My suggestion:
It would be way cooler to drill a hole through the roof of the cave in the right location. I am not sure what kind of drill it would take, but a well driller should be able to do it. From a code perspective, you just tell the inspector that it is a masonry chimney. You would want to build a small rock chimney on the top of the cave so that people and things don't fall down the hole.

 

[Simonkenton]

That is wild! What a beautiful cave. Also I like the pic on the link of the girl with the American flag bikini bottom. What happened to her top?

You are a man after my own heart, I used to live in a cave in Washington state but it wasn't as nice as your cave, much smaller.
No bikini girls in my cave.

 

[begreen]

There are metal chimney fireplaces, but these are design properly so that the metal chimney matches the air volume needed for the fire. One solution might be to use a Malm metal fireplace. Note these require class A chimney pipe, not stove pipe. You may be able to put a pair of 30º elbows in the chimney pipe for the offset.
http://www.malmfireplaces.com/

 

[bholler]

You can also use a prefab class a chimney on a regular masonry firebox as well you just use a masonry anchor plate to switch to class a. But i will tell you that enough class a pipe to get up above the ground level above the cave and big enough for a fireplace is going to cost allot. I dont know what you budget is but i am sure you are looking at numbers north of $10000. Might even get to 20

 

[grottoman]

A couple of thoughts from a total newbie:

1) Yes, you can vent a fireplace to a prefabricated metal chimney. People in new houses do that all the time.
2) From a code perspective, the "structure" is probably the built man-made part not the whole cave. So for code you probably only "have to" get the chimney away from there.
3) From a drafting & venting perspective, the cave and the trees do matter. You probably need to get up at least 3 feet above the ground over the cave.

It would probably be easiest to fasten the chimney pipe to the stone of the cave, and run it out and up.

My suggestion:
It would be way cooler to drill a hole through the roof of the cave in the right location. I am not sure what kind of drill it would take, but a well driller should be able to do it. From a code perspective, you just tell the inspector that it is a masonry chimney. You would want to build a small rock chimney on the top of the cave so that people and things don't fall down the hole.

Well now, hey, that's an awesome suggestion.. A little scary but yes...

On your earlier points, #1 is part of what I was looking for, thanks.
#2, right, got it.
#3, I think it'd be better to stop the chimney 'on' the rock face, rather than run it up the 20 feet to the ground, and then up more from there, no? In other words, I have some 20 feet of rock face with just vines to remove, between where the fireplace is and where the 'upper level' and ground begins... So rather than run all the heat all the way up there, why not just vent it 6-10 feet outside the rock face and put spark arrestors and such on there?

Thanks for the excellent drill suggestion- no idea how feasible but definitely a cool idea...

 

[bholler]

Well now, hey, that's an awesome suggestion.. A little scary but yes...

On your earlier points, #1 is part of what I was looking for, thanks.
#2, right, got it.
#3, I think it'd be better to stop the chimney 'on' the rock face, rather than run it up the 20 feet to the ground, and then up more from there, no? In other words, I have some 20 feet of rock face with just vines to remove, between where the fireplace is and where the 'upper level' and ground begins... So rather than run all the heat all the way up there, why not just vent it 6-10 feet outside the rock face and put spark arrestors and such on there?

Thanks for the excellent drill suggestion- no idea how feasible but definitely a cool idea...

It will probably not wrork well at all if you just stop it on the rock face. Not to mention the creosote buildup all over the rock face

 

[grottoman]

It will probably not wrork well at all if you just stop it on the rock face. Not to mention the creosote buildup all over the rock face

Hello bholler, thank you-

I understand the point of the creosote buildup (although the cave interior has had lots of fires in it and it's all part of it), but what do you mean when you say it wouldn't work well- the draft, or ?

I guess the way to think about it is; pretend the structure is a normal house. I put a fireplace (prefab) 'outside' the wall, with the surface flush with the interior wall, and the chimney just goes up what in this case is the outside wall. But it's rock, rather than the house. So why wouldn't it draft up the side of the rock and go on?

I have about 12 firepits I run inside the cave center (between the cabin and the structure). They all draft just fine up and out even starting inside the cave...

But maybe I missed your point.

 

[Doc C]

Hello bholler, thank you-

I understand the point of the creosote buildup (although the cave interior has had lots of fires in it and it's all part of it), but what do you mean when you say it wouldn't work well- the draft, or ?

I guess the way to think about it is; pretend the structure is a normal house. I put a fireplace (prefab) 'outside' the wall, with the surface flush with the interior wall, and the chimney just goes up what in this case is the outside wall. But it's rock, rather than the house. So why wouldn't it draft up the side of the rock and go on?

I have about 12 firepits I run inside the cave center (between the cabin and the structure). They all draft just fine up and out even starting inside the cave...

But maybe I missed your point.

What bholler is talking about is the 3/2/10 rule I also talked about earlier. It has been shown many times over the years that if you do not have your chimney a few feet above anything with 10’ then the draft suffers.

I would not go as far as to say that it won’t work but I think that you will have a battle.

Also since it seems that my post earlier was overlooked I think you should also think about when you have inversions. If you don’t get your pipe above the top of the cave I think you will be in a really smoky situation.

I think what you are trying to do is awesome! Also I think that you are going to have to start with the basics that have been tested over the years and then make adjustments for your specific situation.

I really hope you do it because it would be cool to see the outcome!

 

[bholler]

Hello bholler, thank you-

I understand the point of the creosote buildup (although the cave interior has had lots of fires in it and it's all part of it), but what do you mean when you say it wouldn't work well- the draft, or ?

I guess the way to think about it is; pretend the structure is a normal house. I put a fireplace (prefab) 'outside' the wall, with the surface flush with the interior wall, and the chimney just goes up what in this case is the outside wall. But it's rock, rather than the house. So why wouldn't it draft up the side of the rock and go on?

I have about 12 firepits I run inside the cave center (between the cabin and the structure). They all draft just fine up and out even starting inside the cave...

But maybe I missed your point.

It may work fine. But in many cases when the chimney outlet is to close to an object it can effect the draft severly. In some wind conditions it can reverse. That is the reason for the 3 2 10 rule. And firepits dispersing their smoke across the whole roof of the cave is very different from a chimney dumping smoke in one spot on a rock face. You will have massive amouts of buildup there.

 

[grottoman]

What bholler is talking about is the 3/2/10 rule I also talked about earlier. It has been shown many times over the years that if you do not have your chimney a few feet above anything with 10’ then the draft suffers.

I would not go as far as to say that it won’t work but I think that you will have a battle.

Also since it seems that my post earlier was overlooked I think you should also think about when you have inversions. If you don’t get your pipe above the top of the cave I think you will be in a really smoky situation.

I think what you are trying to do is awesome! Also I think that you are going to have to start with the basics that have been tested over the years and then make adjustments for your specific situation.

I really hope you do it because it would be cool to see the outcome!

Hello Doc!
I'm sorry, I didn't totally miss your earlier post but I wasn't quite sure I understood and forgot to poke about some of it.
I don't know what you mean by inversion, for instance (some sort of down draft or the like, or reversal of the airflow down into the structure?)
Regarding the 3/2/10, help me understand 'having chimney a few feet above anything with 10'. Ten feet of clearance above the top of the chimney, or ?

Thanks for educating me.

It will be cool if I can figure it out, ha!

 

[Doc C]

Hello Doc!
I'm sorry, I didn't totally miss your earlier post but I wasn't quite sure I understood and forgot to poke about some of it.
I don't know what you mean by inversion, for instance (some sort of down draft or the like, or reversal of the airflow down into the structure?)
Regarding the 3/2/10, help me understand 'having chimney a few feet above anything with 10'. Ten feet of clearance above the top of the chimney, or ?

Thanks for educating me.

It will be cool if I can figure it out, ha!

No worries. I call it analysis paralysis. So much information sometimes.

Inversion is seperate from the chimney. In layman’s terms it would be when air is trapped near the ground. It would be something to consider in your case because if you are not getting enough to draft and you have an inversion happening in your area then your problems will be compounded by the smoke coming straight back down to the ground and into your cave.

“An inversion can also suppress convection by acting as a "cap".”

https://en.m.wikipedia.org/wiki/Inversion_(meteorology)

It’s very common in certain areas of the country.

The clearance requirements for the top of the chimney, put simply, any structure within ten feet of the top of your chimney as measured to the side of the chimney will have a negative affect on draft. This is the reason that chimneys need to be above the ridge on a house, assuming the ridge is within 10’ of the chimney. I would think the same should apply in your case to the cave.

 

[grottoman]

That is wild! What a beautiful cave. Also I like the pic on the link of the girl with the American flag bikini bottom. What happened to her top?

You are a man after my own heart, I used to live in a cave in Washington state but it wasn't as nice as your cave, much smaller.
No bikini girls in my cave.

Ha!
Thanks Minister.
I like my cave, and the visitors, as well.
I don't know the answer to your question- but a general response may suffice as 'what happens in the cave stays in the cave'.

 

[grottoman]

There are metal chimney fireplaces, but these are design properly so that the metal chimney matches the air volume needed for the fire. One solution might be to use a Malm metal fireplace. Note these require class A chimney pipe, not stove pipe. You may be able to put a pair of 30º elbows in the chimney pipe for the offset.
http://www.malmfireplaces.com/

Thank you, begreen.
Those are interesting. Putting one just outside the structure with the face flush to the interior might work.
But a bit too formal for the cave environment I think.

 

[grottoman]

Thank you all for your feedback, it's been enlightening and unlike many bulletin boards, I got zero snarky replies about how stupid my thoughts were, ha!

But let me throw this last log on the fire:

If I had the cave and not even the house inside it, and I made this little first structure with 3 walls and a few windows, and the year was 1750 or 1850, don't you think it would be reasonable to think that a small brick and mortar fireplace that had a simple brick chimney that went up just above the bottom of the rock face (as opposed to ten feet above the top) would have been successful?

I guess I'm asking
-have our regulatory and performance and safety guidelines gone too far?
-or is it unreasonable and unsafe for me to try sticking a small woodburning pref fireplace in, and having a 20-30 degree bend in a prefab metal chimney that went up about 6 feet?

On that last note, here is the closest I've gotten: I think there may be a 42", but as an example, this 36" that seems to have a circular chimney vent. Could I not just add a circular metal vent to this, and put a spark arrestor / spark guard at the top of it? And have that fireplace butt just up to the cliff edge, and the chimney pipe run about 6 feet up? I find it hard to believe that on cold days (when I'd use it), it wouldn't have plenty of draft, but I guess I could make the pipe taller until it worked well, no?

[prefab fireplace]
https://www.efireplacestore.com/sup...MI3ZSv6pnl1wIVwoKzCh1TYAMKEAQYASABEgJ7__D_BwE

[chimney pipe]
https://www.efireplacestore.com/fsd-148-8dm.html?refnum=NOV-663-2878

 

[jatoxico]

Wait, the cave has goddess rituals?? This deserves much more serious thought.

 

[jatoxico]

If I had the cave and not even the house inside it, and I made this little first structure with 3 walls and a few windows, and the year was 1750 or 1850, don't you think it would be reasonable to think that a small brick and mortar fireplace that had a simple brick chimney that went up just above the bottom of the rock face (as opposed to ten feet above the top) would have been successful?

I guess I'm asking
-have our regulatory and performance and safety guidelines gone too far?

Thing is we know better now what reliably works day in and day out and what could potentially be an issue. So you can't expect anyone here to recommend something that has the potential to be unsafe.

 

[grottoman]

Thing is we know better now what reliably works day in and day out and what could potentially be an issue. So you can't expect anyone here to recommend something that has the potential to be unsafe.

Regarding your earlier post- Ha!

Regarding this-

Right; I'm not asking for something to be unsafe- my point is that the regulations and reliability guidance may not be applicable to a cave.
In other words, all the regulations around the fireplace box itself, the flooring underneath it, and the distance to combustibles around it are logical and apply to the structure.
But the rules around the chimney and its distance from objects for both safety and reliability don't seem like they are all necessarily applicable to this context (i.e., an outdoor location with a rock wall and some 20 or 30 feet up to trees above..)

If a tree were above a house chimney, but it was 30 feet above the chimney which had an arrestor, would that be an issue?
Regarding the reliability, do I care that much about draft and creosote on the rock wall, as long as the smoke doesn't sit inside the structure?

Again, thanks for the thoughtful commentary, and glad some of you are enjoying the images.

Did you not see the firedancers? The live Dracula performance was also epic. He was slain in the back of the cave with a spike to the rock through his heart.

Good stuff.