Updated January 15th, 2023
Nothing beats sitting around a fire with friends in the evening. Lava rocks are a popular filler for gas and propane fire pits. Nothing ruins that evening faster than lava rocks exploding in fire pit flying out at everyone. Why do lava rocks explode in the fire? More importantly, how do you stop lava rocks from exploding in the fire? Let’s take a look.
Lava rocks exploding in fire pit. Why do lava rocks explode?
Lava rocks are very porous like a sponge. Water can get trapped inside of lava rocks when they get wet. When the wet lava rocks get heated up by the fire, the water inside turns to steam and expands. This creates pressure inside of the lava rocks which can cause them to explode open.
There are a few easy things to do to stop lava rocks from exploding in your fire pit.
Step 1 – Cure new lava rocks
When you get a new propane or gas fire pit that includes lava rocks, it is a good idea to cure them first. Even if they say they are pre-cured it is a good idea to follow this process. If you get new lava rocks to add to your fire pit or replace old rocks, you will want to do this again.
- Put your lava rocks into your fire pit.
- Light your fire pit and turn it up to high
- Cover your fire pit with a metal grate. This will prevent lava rocks from flying out of the fire pit.
- Stand at least 15 feet back from the fire pit while it is burning.
- Let the fire pit burn for at least 10 minutes on high while standing away from it. This will dry out the lava rocks. If the lava rocks start exploding you should continue heating them on high heat until they stop. If the rocks haven’t been cured before it may take up to 45 minutes to completely dry out the rocks.
After this you can use the fire pit normally without covering it or standing back from it.
For more information on curing lava rocks see the instructions included with Camp Chef Portable Fire pits. You can also read more information from Flame Creations that they include with their lava rocks.
Step 2 – Cover your fire pit when not in use
To keep your fire pit from having exploding lava rocks you want to keep the lava rocks dry. If you leave your fire pit outside, cover it so that the lava rocks won’t get wet. Keeping your fire pit covered when not in use will keep the lava rocks dry. If you have a fire pit outside in a low lying area that can collect water, or have a water feature such as a waterfall with your fire pit, you should look for a different filler for your fire pit. Consider lava glass instead of lava rocks if you know you can’t keep the lava rocks dry.
Step 3 – Dry out lava rocks if they get wet
If your lava rocks do get wet or rained on, you will want to dry them out. If the lava rocks get really soaking wet, you will want to go through the curing process again. If they just got a little wet you don’t need to cure them again. You should run the fire pit on low for 15 to 30 minutes first to warm and dry the lava rocks before turning it up to high.
Hopefully these steps will keep you from having lava rocks exploding in fire pit in the future. Always use caution when using fire pits and never leave them unattended while burning.
Lava Rock FAQ
Q: Why are my lava rocks exploding?
If your lava rocks are exploding in your fire pit, it is because they have water inside the rocks. Lava rocks are porous like a sponge. If the rocks are wet, water can get trapped inside of them. When you heat the lava rock up, the water turns to steam. When it turns to steam it expands. This expansion of the water can break open the lava rock making it explode. The below video demonstrates how wet rocks can explode in a fire.
Q: Does lava rock explode when heated?
Lava rock can explode when heated if it has water trapped inside it. If the lava rock is dry it won’t explode. If you have new lava rock or lava rock that got wet you should cure it using the method listed above.
Q: Is lava rock good for fire pits?
Lava rock makes a good substance to put into your fire pit. Lava rocks help disperse the flame giving it a more natural look. They will look similar to a flame coming up through hot coals. Lava rocks help spread out the heat. Heat coming out of the burner will go straight up. If you put a layer of lava rocks on top of the burning it will redirect the heat all around. The rocks themselves will heat up and start radiating heat. This gives a gas fire a much warmer feel for sitting around it.
A fire pit full of lava rocks will look like a more natural fire flame and it will radiate heat better.
Q: Why is my fire pit popping?
If the lava rocks in your fire pit are popping, they have water trapped inside. This water is turning to steam, expanding and blowing open the rocks. If this is happening you should stand back from the fire pit for 15 minutes until all the lava rock has cured or dried out. Once the lava rock is dry inside it won’t pop or explode anymore.
Q: Is fire glass better than lava rock?
Lava glass gives a different appearance from lava rocks. Lava rocks are porous and look rough. Lava glass has a dark glass appearance to it. Lava glass isn’t porous so it won’t get water trapped inside it. This means it doesn’t need to dry out to stop exploding. Lava glass is much better to use if your fire pit is somewhere it will get wet.
Q: Can rocks explode in fire?
Some kinds of rock can explode in your fire. Rocks that are porous such as lava rock, river rock or sandstone can have water trapped inside of them. As they get hot the water turns to steam and expands breaking open the rock. The answer to this is to cure or dry out the rocks so they don’t have any moisture in them.
Q: Should I put sand in my fire pit?
There are good and bad reasons for putting sand into a fire pit. You should check the manual for your fire pit to see if it recommends using sand. Sand can protect the metal bottom of your fire pit from the flame. If your fire pit burns wood, the sand will mix with the ashes. Some people use the ash for fertilizer or other purposes and sand will contanimate it.
Q: Can rocks explode when boiled?
Yes. If the rock had water trapped inside of it before being heated in boiling water it can explode. The trapped water inside will turn to steam and expand cracking open the rock. If you use rocks to boil water, you should use dry rocks. Choose rocks you found in a location that wasn’t likely to get wet. Don’t choose rocks from a stream bed or dried up pond. These rocks may have been underwater and have water trapped inside of them.
You might also like:
- The Best Portable Propane Fire Pits Helpful Guide
- How Long Do Lava Rocks Stay Hot? 9 Helpful Facts About Lava Rocks
- Can You Use A Propane Fire Pit On A Trex Deck? 5 Helpful Fire Pit Tips
- 5 Easy Ways to Keep Your Fire Pit From Filling With Water
About the author
My name is Doug Ryan. I am a homeowner and love having get togethers and finding the best things to make spending time at home easier and more fun. We spend a lot of time at home so why shouldn’t we have a great time there? I decided to start Great Home Gear as a way to share my knowledge and enthusiasm for all things home living with everyone.