Denver Decorative Concrete & Custom MasonryI have big pcs of flagstone in my yard and I wanted to use it to make a firepit, can flagstone withstand heat?
My goal was to dig a hole and lay a couple of the larger stones on the bottom, grade up the sides and cover them with smaller stones, then make a few layers of the flagstone at the top. I heard that some stones can explode (ie. sandstone). PS. I am time challenged right now and in a pinch for a firepit so this is just a temporary fix, since I have a bunch of flagstone laying around, I thought I would put it to use and I would solve the fire dilemma. I just do not want to explode!!!
I would think it is ok, it is a rock material, they also place it on homes, if its short term i would do it, try burning a piece with gasoline or wood, i still think its ok its rock
The only thing that can be a problem is rapid heating or cooling or uneven heating or cooling. This can cause just about any rock to crack.
If it is really wet and you start a fire you can be an explosion from the trapped moisture but I doubt it will be much more than the type of popping you can get with slightly damp firewood.
I would heat it slowly the first time and then you should be okay.
You’re correct in thinking sandstone will shatter,slate and granite are probably the only materials that would withstand the heat of a fire.
Any stone is liable to suffer thermal shock if some part is exposed to greater heat,unequal expansion could cause breakage.
Using firebricks,or casting a rough firepit from concrete would be cost effective and a long term solution.
you’re taking a risk if you do not use ‘firebrick’ to line the bottom and sides where the actual fire will be…. once you have that, you can decorate with the flags any way you like, but the firebrick should be the containment… that’s what they’re made for…..
http://www.home-landscape-plan.com/building-a-fire-pit.html
another possible is the steel ring, like here…
http://www.thisoldhouse.com/toh/how-to/overview/0,,1636191,00.html