How To Use Lava Rocks For A Fire Pit

How To Use Lava Rocks For A Fire Pit in 2023

Lava rocks are an essential element in a propane or natural gas fire pit and can also be used in wood-burning fire pits. They are composed of basalt – rock that can tolerate extreme heat without exploding. Lava rocks help to evenly spread the flames, distributing and retaining the heat. 

To protect the critical components in a fire pit from the elements and shield them from the extreme heat of the flames, fill the base with 2 to 5 inches of lava rock. There are fire pit lava rock calculators to determine how much is needed for a particular size fire pit. They last around 2 years.

Compared to other fire pit media, like fire glass, lava rocks are affordable and durable. This article explains why and how lava rocks are used in fire pits and how to start a gas fire pit with lava rocks.

See Glass vs Lava Rock – what’s the difference. Plus how to use river rocks in your fire pit.

The Purpose Of Lava Rocks In A Fire Pit

Besides their aesthetic appeal, lava rocks are functionally important in a fire pit. Without them, the heat coming from the burner would radiate skyward.

Adding a layer of lava rocks to the bottom of a fire pit helps to distribute the flames and causes the heat to radiate outwards from the burner.

This creates a warm, comfortable campfire atmosphere for the people gathered around the fire pit. The rocks retain heat for hours. 

Lava rocks are also beneficial for the life span of the fire pit. They shield the burner from extreme, direct heat from the flames. This protects it from developing hot spots and cracking. 

The rocks also shelter the fire pit components from the elements. If your fire pit does not have a cover and gets rained on, the lava rocks help drain the water.

Can I use lava rocks with fire glass?

Should I put lava rocks in my firepit?
Should I put lava rocks in my firepit? They are a safe rock for a fire pit.

Lava Rocks In a Gas Fire Pit

Gas fire pits require some type of medium to help with heat distribution and protect the critical components from the heat of the surface flames. One can use fire glass, fire rock, or lava rocks.

Depending on the fire pit’s size and design, you will need to add a 2-to-5-inch layer of lava rocks. Read your fire pit’s user manual to see how much to use.

This online fire pit lava rock calculator can accurately determine how much you need.

Lava Rocks In Wood Burning Fire Pits

Wood burning fire pits need a 4- or 5-inch layer of lava rocks on the bottom to prevent hot spots from forming. These can cause the fire pit to crack.

Lava rocks help with heat retention and distribution in wood-burning fire pits. The logs are placed atop the lava rock layer.

How to clean a fire pit

How To Put Lava Rocks In A Fire Pit

Before adding lava rocks, make a base layer using sand or gravel. 

Use smaller sized lava rocks as the first layer. Add them to the fire pit so that the burner is just covered. This creates a sturdy foundation for the next layer and provides excellent drainage. 

Larger sized lava rocks, or ones that have been tumbled, are then packed on top of the base layer. To make your fire pit more decorative, you can mix in some fire glass.

It is essential to regularly check that the drainage holes in the fire pit do not get blocked. Water has to be able to flow out of the bottom of the fire pit if it is rained on.  The rocks should dry out before high heat is applied.

Where do lava rocks go in a fire pit?
Where do lava rocks go in a fire pit? Lava Rocks go on top of a sand base.

Lighting A Gas Fire Pit With Lava Rocks

For a fire pit with a push-start ignition button:

  • Remove the lava rocks around the burner.
  • Slightly open the gas valve
  • Press and hold the ignition to light the fire.
  • Using a pair of tongs, place the lava rocks back around the burner to cover it.
  • Toggle the valve to adjust the flame.

For a fire pit without an ignition button:

  • Remove the lava rocks around the burner and slightly open the gas valve.
  • Using a long match, light the burner.
  • Place the lava rocks back over the burner.
  • Adjust the flame by slightly opening or closing the gas valve

Can Lava Rocks Crack Or Explode?

Lava rocks can explode if the fire pit is used while they are wet. The rocks are allowed to get wet, but it is critical that they thoroughly dry before you light the fire pit. 

Because lava rocks are porous, they can suck up water like a sponge. If they are heated, the water inside them turns to steam and expands, cracking the rocks open.

To dry lava rocks that have gotten wet, light the burner and leave it running on low for half an hour. Make sure pets and kids stay far away from the fire pit during this time. You should hear the rocks popping.

To prevent this issue altogether, cover your fire pit when it rains or snows

What happens if lava rocks get wet?
What happens if lava rocks get wet? Water may get trapped in the rock – so make sure they are dry before you go high heat mode or they can crack or even explode.

Benefits Of Lava Rocks In A Fire Pit

Using lava rocks in your fire pit has many perks:

  • It is the most affordable fire pit medium, only costing $2-3 per pound (fire glass can cost up to four times more).
  • Low maintenance because it does not require frequent cleaning, like fire glass.
  • Lava rocks are easy to clean. Rinse them off once a year to remove dust.
  • They are safe to cook over, so you can happily roast marshmallows.
  • Lava rocks are durable and last for about 2 years, depending on how much you use your fire pit.
  • They extend the life of your fire pit by reducing wear and tear.
  • They look more natural than other fire pit mediums
  • Lava rocks come in a range of colors from grey to black and brownish brick-red. 


Lava rock is a brilliant, low-cost fire pit medium. Add a 2-to-5-inch layer to the bottom of a fire pit so that the burner plate is just covered. This will protect the burner components from heat, sun, and rain.