What do I put in the bottom of my fire pit? [ANSWERED]

You all know that we feature an assortment of DIY fire pits — folks frequently use the pictures as inspiration for their own designs and projects. Reader Sarah H. was browsing earlier this week and had a question regarding something we frequently overlook when adding fire pit content.

“Hey guys, great site. I was wanting to build a fire pit in my backyard and was wondering what do I need to put in the bottom? Thanks!” – Sarah H.

We’re always excited to help our readers begin their journeys, so rather than sending her a short email we decided to fully answer the question. To save some time for you experienced fire pit masters, I’ll give the TLDR right here:

Fire Pit Liner Materials

Which Material Should I Put In The Bottom of My Fire Pit?

Each of the materials listed above have their own pros and cons. You’ll have your own priorities / trade-offs in mind and I can’t make the decision for you. I can say that the most versatile material to put in the bottom of your fire pit would be sand. It’s relatively cheap, easy to install, and provides an excellent heat shield. But if you’d like to know more about the various options and how they might apply to your situation, feel free to read on.

Can I Put Dirt In The Bottom Of My Fire Pit?

Dirt has the benefit of being free, easy to install (it’s already there!), and resistant to heat. However, the ash can mix with the dirt and create a terrible muck. If this muck were to get wet, you’d have a real mess on your hands. It’s easy enough to clean — if you have a shovel you can dig it out and start over. But if you’re putting dirt in the bottom of your fire pit, you should know that it can be higher maintenance.

Are Lava Rocks Good For Fire Pits?

Lava rocks are specifically designed to be placed in the bottom of your fire pit. Not only are they pleasing to look at, but they’re extraordinarily conducive to heat. Unlike other stones, you don’t have to worry about them cracking, breaking, or exploding either!

“Lava rocks” are typically made out of obsidian, created from magma. If they didn’t explode then, they won’t in your fire pit. Just like with dirt, you might have higher maintenance overhead (unless you also have a gas fire pit).

We actually have a recommendation for the type of lava rock to purchase.

Our Recommendation

American Fireglass LAVA-M-10

They may not look like much, but they do the job. Not to mention they’re incredibly economical (I’m not kidding: check out the price. It might make your jaw drop!).

Should I Line The Bottom Of My Fire Pit With Sand?

We’ve already covered the benefits of sand, but to recap:

Pros:

However, we didn’t address the potential concerns for putting sand in the bottom of your fire pit. For one, it’s harder to install than dirt. You have to buy the sand from a landscaping store, transport it home, carry it to the site, and put it down. This requires a lot more involvement than shoveling dirt from one location to another! Additionally, the ash can mix with the sand just as it does with dirt, creating a less messy but similarly problematic muck.

Lining The Bottom Of Your Fire Pit With Fire Pit Glass

Fire pit glass is another great alternative to line the bottom of your fire pit. Unlike the lava rocks mentioned above, fire pit glass is man-made and can come in a wide assortment of colors and patterns. It doesn’t radiate heat as well as lava rocks (and it’s more expensive than sand/dirt), but some folks love the way the flames dance in the reflection of the glass.

If you’ve built your own wood burning fire pit, you’ll also have your hands full cleaning the fire pit glass every few weeks. But it can make for a marvelous sight!

Our Recommendation

Mr. Fireglass Recycled Fire Glass

We chose the Mr. Fireglass fire pit glass for a reasons:

Can I Line My Fire Pit With Rocks?

In another article we covered the dangers of building your fire pit out of river rocks. But can you put rocks in the bottom of your fire pit? Although smaller rocks carry less of a danger of exploding like large river rocks might, we’d still suggest avoiding this option unless you use tiny rocks (around the size of a dime). This will reduce the danger by reducing the damage an exploding rock can do. But it doesn’t completely eliminate the danger, and we would urge you to use caution!

Lining the bottom of your fire pit with gravel

One of the first fire pits I ever built had gravel in the bottom. I was living on a farm and we had an ample supply of the stuff, so it seemed like a natural fit. It worked well enough, although if you don’t already have a good supply of it, sand seems like the better choice. However, it’ll do great in a pinch!

Can I Put Sand In A Metal Fire Pit?

So far, I’ve been assuming your fire pit is built into the ground (a DIY fire pit, essentially). But if you have a metal fire pit, can you still put sand in the bottom of it? While sand retains moisture extremely well, I’d still recommend you put about an inch or two of sand in the bottom of your fire pit. Reason being, the sand helps evenly distribute the heat from the burning fire. This helps you and your guests stay toasty!

I would honestly avoid putting any sort of liner in a metal fire pit (the metal handles this job fine). But if you’re worried about heat transfer, you can always try and get a heat shield or fire pit mat (We wrote an article on fire pit mats, you should check it out!).

Can I Put Sand In A Gas Fire Pit?

Finally, can you put sand in the bottom of a gas fire pit? Yes — but you have to pay special attention not to cover up the gas outlets / igniters. If you’re careless with the installation, you’ll find that you won’t be able to produce a meaningful flame! And of course, there are other materials better suited to line gas fire pits (fire glass and lava rocks come to mind!).

Final Answer

How you set up your fire pit is completely up to you. But yes, you can put sand in the bottom of your fire pit. There may be other materials better suited for your purpose (like gravel if you have it, or dirt if you don’t want to spend any extra money/time). If you have a gas fire pit, your options open up quite a bit.

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6 Comments

  • Judy Lease says:

    I want to use black obsidian rock in my new firepit with a metal pan. I just read that with larger stones on the bottom I will risk gas pooling–not sure what problems happen. Do I need small pieces all over the bottom of the 20″ pan? How small? How thick? How high do i put the rock?

    Do I need to worry about obsidian blowing up? I think it will look beautiful; I plan to add some fire rock for color and reflection. Good idea?

    I’d sure appreciate some comments. Judy

  • Roger Mort says:

    Can I use Sand under my Metal Liner? I have above ground stone fire pit. Sets on a paver patio. The liner needs to be raised anyway. I was wandering if I could just use enough sand to raise and then insert my liner.
    One last question: what gauge steel would you recommended for a good liner?

  • Stephen J. Lestingi says:

    I have a pressed concrete patio, when it was poured we didn’t have a whole put in the patio. Eventually my wife wanted a pit, so I built a block fire pit now, what Can I put down or need to be done to be able to use the fire and keep the the damage to patio to a minimum??
    Please help!! Haha

  • Seaside Brian says:

    How about seashells as a filler?

  • Veronica kalmes says:

    I have a Weber 2726 firepit For years which we love and have had the lid and bottom replaced and would like to replace again! Years of enjoyment

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