cobblestones for outdoor fireplace?


  #1  
Old 09-12-16, 07:21 AM
eddieo45's Avatar
Member
Thread Starter
Join Date: Feb 2005
Location: Milton, MA
Posts: 316
Received 0 Votes on 0 Posts
cobblestones for outdoor fireplace?

I'd like to relocate my patio firepit to a spot atop a large granite slab, in an effort to reduce the amount of smoke wafting into my eyes. I had initially built the patio around the firepit location as seen in these photos, which also clearly show the granite slab on the right:

Name:  fire pit.jpg
Views: 2188
Size:  50.4 KB
Name:  patio, phase 1.jpg
Views: 1737
Size:  50.5 KB

I've seen some simple designs that maximize the open view of the fire while guiding the smoke upward:

[ATTACH=CONFIG]70782[/ATTACH]
[ATTACH=CONFIG]70783[/ATTACH]
[ATTACH=CONFIG]70784[/ATTACH]

Cobblestones seem a better choice for this than the random beach stones I used before but what should I use for mortar? The examples I cite above appear to NOT be mortared in place but I'd rather have some durability and permanence.
 
Attached Images    
  #2  
Old 09-12-16, 09:16 AM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 25,238
Received 892 Votes on 822 Posts
Most regular stones and concrete pavers are not good for a fire pit. The heat from a fire will cause them to split and sometimes even explode. If you want something formal and mortared I would build the interior of the fire pit with fire bricks. Then you can use whatever material like field stones or pavers on the outside.
 
  #3  
Old 09-12-16, 01:37 PM
eddieo45's Avatar
Member
Thread Starter
Join Date: Feb 2005
Location: Milton, MA
Posts: 316
Received 0 Votes on 0 Posts
If I go without "formal and mortared", would stacked cobblestones like the first two photos work okay? Seems like most of the heat would go straight up and out....
 
  #4  
Old 09-12-16, 04:35 PM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 25,238
Received 892 Votes on 822 Posts
Most rocks and standard bricks can crack, pop and rarely explode when exposed to the heat of a bonfire. If you've ever stood beside a fire and felt the heat you know that heat not only goes up. It is radiated out in all directions.
 
  #5  
Old 09-12-16, 04:52 PM
B
Member
Join Date: Oct 2008
Location: New England
Posts: 10,524
Received 37 Votes on 34 Posts
To keep that smoke from chasing you all around the fireplace you need a chimney of sorts. Once you establish a vertical column of lighter air above the fire, that will be the direction of air flow. Left open the hot air above a fire can easily be blown away with a slight wind and then the smoke is free to go after you.
Google "open fire pit with chimney pictures" for some ideas.

And I agree with Pilot, anything but a fire rated brick is a potential problem. Add to that, that a completely open fire has a risk of someone falling into it. Some of the enclosed ones you will see in that link will have screens to keep embers where they belong.

Bud
 
  #6  
Old 09-13-16, 05:48 AM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 25,238
Received 892 Votes on 822 Posts
Notice that the photos you included in your post don't show those fire pits being used. Most are perfectly clean with logs "staged" inside. The one photo that does show a fire you can see that there is no soot or charring on the rocks so that's possibly it's first use.

Read a bit of history and you'll find that fire was one of the methods used to break rocks when mining and tunneling before the invention of explosives. There are some stones that can withstand the heat of a fire. Lava rock is best known and seen in many propane grills. There are others but often you'll have to experiment to find which will work and which won't.

I had a dry stack fire ring made with bricks and local field stones. After each fire a few more rocks & bricks would crack and break. There were a few stones that withstood it though but it's hard to tell just by looking at them if you haven't studied a bit of geology.
 
  #7  
Old 09-13-16, 09:45 AM
eddieo45's Avatar
Member
Thread Starter
Join Date: Feb 2005
Location: Milton, MA
Posts: 316
Received 0 Votes on 0 Posts
I appreciate your expertise and your advice. I must have gotten quite lucky with the beach rocks I lines my current fire pit with (second photo from top). I've had several fires with both brush and hardwood and haven't cracked a stone yet. I'm gonna talk to a stone mason near my house as well. Thanks again for the tips.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: