Can heat from a homemade stone fireplace make the rocks explode or is that just a myth?

The reason i'm asking is i want to build a stone fire place for my cabin and i don't want the rocks to blow up on me when i light the fire.

Public Comments

1. unless you are burning jet fuel i think you'll be safe. there is no way a typical wood fire can get stones hot enough to explode.
2. i've had 4 geology classes and i have NEVER heard that myth. i think you'll be ok.
3. It's not a myth. A wood fire can make rocks explode. Here's why and how: Some rocks are porous and hold a considerable amount of water. If the wet rock is heated, the water will boil at 212 degrees F. well within the capabilities of a wood fire. Steam will be created at a considerable pressure, and the rock will explode. This is why you should never use rocks from a stream when building a campfire. Cement blocks and bricks also hold water and can explode if heated quickly enough. Having said all that, you can safely build your own fireplace. Get a book that explains the technique and follow the directions. Pick stones that are solid, and ensure that they have had a long time to dry if you use something like sandstone which can hold a lot of moisture. Solid granite stones might be best but you can use whatever is available in your area. Just ensure they are well cured before setting any fires.
4. Trapped water and air can both cause rocks to explode. What happens is you are heating an enclosed area. The heat causes expansion and if there is no release for the pressure, it explodes. You could always "test fire" the rocks in an outside fire before installing inside.
5. The inner core of the fireplace should be made of fire brick,not stone.The stone is for cosmetic use only on the outside.They will crack and split apart with high heat.
6. Hi - Don't, under any circumstances, use ordinary pebbles/rocks. You need to purchase pebbles/stones made from refractory ceramic fibres (RCF’s) which vary in composition but are non hazardous. The dies and stains used to colour them are also non toxic. Google 'Fire Pebbles' to track down a source local to you.
7. Rocks will crack and pop and explode if they get to hot especially ones that are very porous such as sandstone...you will be just fine though as long as you use firebrick inside the fireplace...one of the most importsant things to worry about is that you get the foundation for the chimmney properly made so it will not settle to much or be unable to properly hold chimmney up...
8. you will build your firebox out of firebrick so there will be no problem with exploding stone...use solid red brick for the throat and flue liners for the stack
9. If your fire gets hot enough to explode stones you'll have nothing to worry about because you will already be a dead pile of ashes in the middle of that room before it gets hot enough to explode rocks. Most of your cabin will also be gone too, well except for the fireplace and chimney.
10. In Finland we had maybe million+ saunas which were heated by wood under regular stones, granite or river rock. The stones made the sauna hot, like 240F air temp. We would throw water on the rocks to get hot steam and get the temp to go upto a point that we would get goose bumps (pores open up) and start heavy sweating I never heard of exploding rocks. Many people built saunas on their on out in the country by one of the country's 200K+ lakes. I would still make the inner walls and chimney out of concrete blocks or fired bricks. You need the inner surface to be smooth for cleaning out soot to avoid fp to get a burn inside the chimney (very dangerous - I don't know what it is called) Also get info on how to build an air circulator - the system sucks cold air from bottom and blows hot air over the top of the fp. It's pretty inexpensive to do and pays for it self if u live in a cold climate. A fp is ineffective as a heater since it sucks warm air out of the house upthe chimney. That air will be replace from leaks into the home from the outside.