A fire pit can be an excellent addition to your backyard to provide warmth, ambiance, and an elegant touch of rustic charm.
Beyond the undeniable aesthetic appeal, fire pits are also practical because they can extend the usable season of your outdoor space while boosting the overall value of your property.
While building one, a crucial element to consider is the kind of stones and rocks to use for a fire pit, and that’s where this guide comes in handy!
In this article, I’ll walk you through some of the common materials to consider and avoid, along with their advantages and drawbacks. Let’s dive right in!
Common Types of Stones and Rocks Used for a Fire Pit
There are a variety of popular choices when it comes to stones and rocks used inside and outside fire pits.
Here’s a brief overview of each one of them along with their advantages, disadvantages, and best use cases.
1 – Lava Rocks
Lava rocks, also known as “Basalt”, are one of the most popular types of rocks used in fire pits.
As the name suggests, lava rocks are a type of volcanic rock with natural heat-resistant properties.
It also has a unique heat circulation due to its high porosity in which it absorbs heat and radiates it throughout the day.
Additionally, lava rocks come in a variety of natural colors and sizes, so you can pick the ones that suit your style the best.
These advantages make it a perfect choice to use around the fire pit as well, especially if you want to keep the fire pit area warm for longer.
Can You Use Lava Rocks in a Fire Pit?
Lava rocks are one of the best materials to use as a base inside a fire pit. They’re highly durable and resistant to heat, so they last a fair bit of time.
Lava rocks also don’t require high maintenance or upkeep, as you only need to soak them in water, remove debris, and let them dry completely before they’re ready to be back in the fire pit.
Additionally, lava rocks are readily available in a variety of looks while being fairly affordable.
The high porosity of the rocks means that they stay dry and don’t hold in moisture after rain. However, they do pop loudly quite often due to their porous nature, so you should keep that in mind.
How Long Do Lava Rocks Last in a Fire Pit?
The answer mainly depends on how often you’re going to use the fire pit and the level of maintenance and care you’ll put into keeping the rocks clean.
Ideally, you should expect lava rocks to last anywhere between 3 to 5 years in perfect conditions. Keep in mind that moving them around while it’s hot can break them up faster.
2 – Glass Marbles (Fire Glass)
At first glance, regular glass marbles might seem like a good material for a fire pit, but unfortunately, this is not the case.
While these marbles may seem heat-resistant and provide a unique aesthetic, they’re not designed to withstand the high temperature of a fire pit. As a result, they can crack and explode under pressure.
However, you can still use glass beads and marbles in fire pits, but you must make sure that they’re made from fire glass.
Fire glass is a type of tempered glass specifically designed to handle the high temperature of a gas fire pit without collecting soot or exploding.
Can You Use Glass Marbles in a Fire Pit?
You can use glass marbles as a base material and insulator inside a fire pit, but you have to make sure that they’re made from fire glass rather than regular glass.
Besides the reliability of fire glass, they can be made in a variety of colors, so they can even enhance the appearance of your fire pit with their vibrant colors and reflective properties.
3 – Limestone
Limestone is generally a strong and durable stone that can withstand the heat of fire to a certain extent and has a unique texture that gives it an attractive appearance.
Similar to lava stone, it’s also a porous material that can radiate heat and make it comfortable to sit around the fire pit. This makes it a perfect material to build the walls of a fire pit.
Can You Use Limestone in a Fire Pit?
While limestone is a decent choice for a fire pit design and exterior walls, it’s not always a good choice as a base material inside the fire pit.
The extreme direct heat, combined with high moisture from rainfall, can increase the pressure inside limestone, causing it to pop and explode.
For that reason, limestone is only suitable for fire pits if you live in a relatively dry region with little rainfall or roofed outdoor areas.
4 – Sandstone
Sandstone is a type of rock formed by compacted sand grains over thousands of years. This gives it a natural beauty and a unique layered look, thanks to its variety of colors and earthy tones.
Despite being essentially sand, sandstone is remarkably durable and resists heat from the fire pit. It can also radiate the heat back like limestone.
Can You Use Sandstone in a Fire Pit?
You can use sandstone inside a fire pit, but keep in mind that it’s not the most durable material out there when it comes to heat resistance.
In other words, while it performs decently well, sandstone typically crumbles and chips away when exposed to direct heat.
5 – Granite
Granite is easily one of the most popular choices when it comes to building a fire pit.
As an igneous rock formed from cooled, crystallized molten lava, it’s incredibly strong and sturdy. It also offers an unmatched resistance to heat, scratches, and weathering.
Granite also retains heat remarkably well, so your fire pit will stay warm and cozy long after the flames have died down.
Additionally, the sleek appearance of granite adds an incredible touch of elegance and sophistication to your backyard.
6 – Concrete
Concrete is a decent choice if you’re looking for a sturdy fire pit, but it still has its limitations.
For instance, concrete is fairly strong and can withstand the heat emitted from fire pits.
It’s also one of the most affordable building materials for fire pits, compared to other types of stones and bricks, which makes it a perfect pick if you’re on a strict budget.
Yet, it’s not the most durable material to opt for, so you should be prepared to see some small cracks here and there with time.
Stones to Avoid for a Fire Pit
Now that you know more about stones and rocks to use for a fire pit, here are some materials to generally avoid:
- Decorative/Painted Stone: Stones with paint, varnish, or other coatings can emit harmful fumes when heated to such extreme levels. Unless the paint is rated to withstand extreme heat, you should generally opt for natural-colored stone.
- Pea Gravel: While large gravel might work to a certain extent, small pebbles of pea gravel don’t heat up evenly. Additionally, their small size raises the internal pressure in the rocks significantly, so they dislodge when they pop.
- Pumice: Some homeowners are tempted to use pumice as a filler for fire pits due to its unique texture. However, being extremely porous, it can hold onto a significant amount of moisture when left outdoors, which causes them to explode aggressively when heated
Final Thoughts
This wraps it up for today’s guide which walks you through the most common types of stones and rocks to use for a fire pit.
Remember to consider the size and shape of your fire pit when choosing stones. Additionally, make sure that the material you’re using is suitable for your outdoor weather.
It’s also a good idea to purchase a little extra of the rocks/stones you’re using to refill them after maintenance.
Ben has a bachelor’s degree in construction engineering. When not constructing or remodeling X-Ray Rooms, Cardiovascular Labs, and Pharmacies, you can find him at home with wife and two daughters. Outside of family, He loves grilling and barbequing on his Big Green Egg and Blackstone Griddle, as well as working on projects around the house.
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