How To Safely Build A Fire Pit On Concrete

  • By: Mike Hale
  • Date: April 6, 2022
  • Time to read: 5 min.

When you are building a fire pit, it would be great to build it on something sturdy because of how it can help prevent things such as erosion and accidental excavation. This may give you the idea to want to build a fire pit on something as sturdy as concrete. Now, this could be anything such as your patio or a dedicated concrete pad for your fire pit. So, in that regard, how can you safely build a fire pit on concrete?

When building a fire pit on concrete, it is best to use something that is more resistant to heat as the base for the fire pit. That is why you might want to use fire brick on the bottom but including mortar or clay as the inner wall because of how they are much more flame-resistant than concrete. 

The thing about concrete is that, as sturdy as it is, it might not be a good idea to expose it directly to heat because of how it might end up expanding or cracking. That’s why, if you want to build a fire pit in a safe manner on concrete, use materials that are able to resist heat more than concrete can and use such materials as the base to make sure that you don’t expose the concrete directly to the flames.

Fire pit

Can you build a fire pit on top of concrete?

A fire pit is a great addition to your home especially because it gives your backyard an amazing atmosphere during the colder nights due to how it can keep you, your family, and your friends warm while you are enjoying an evening of food and drinks together. This is why you might want to think about adding a fire pit to your backyard.

When you are looking to have a fire pit in your home or backyard, one of the most ideal things that you need to consider is that it might be best to make sure that it is placed on top of something that is sturdy. That’s because erosion can be a problem when you build a fire pit directly on top of the ground. Moreover, you could also end up excavating the soil when you are cleaning your fire pit.

So, when it comes to something sturdy, a lot of people would immediately think of concrete as the best material to act as the base for your fire pit because of how is strong and sturdy enough to resist erosion. However, can you really build a fire pit on concrete?

Technically speaking, it should not be a good idea to build a fire directly on concrete. That’s because concrete isn’t very resistant to heat. You may have noticed this on buildings and roads that are regularly exposed to heat in hotter regions in the world as concrete will eventually expand and crack.

However, just because you can’t build a fire pit directly on concrete doesn’t mean that you can’t build it on concrete. You can still build a fire pit on concrete such as your backyard patio or a dedicated concrete plate. However, you shouldn’t build the fire pit directly on concrete, or else you might end up damaging the concrete. That’s why it is best to use a flame-resistant material on top of the concrete to protect the concrete from direct exposure to heat.

How to safely build a fire pit on concrete?

If you want to safely build a fire pit on concrete, here’s what you need to do:

  1. Go grab a compass and use a piece of chalk to draw a circle on the concrete base that you are planning to build the fire pit on. Make sure that you are using 3 feet as the diameter but you can use a bigger one if you want to. This circle is the inner diameter of the entire fire pit.
  2. Use a flame-resistant ready-mix mortar and mix it in a wheelbarrow together with the recommended amount of water. You can also mix it together with clay, which is another flame-resistant material that you can use. Continue mixing until it forms a thick consistency. You can then mix the mortar using a hoe. Before it dries up.
  3. Using a shovel or anything that can scoop, scoop up the mortar and place it on the concrete that is outside the circle that you just drew. Use precast stone blocks and place them on top of the mortar while making sure that there is at least half an inch of room between the concrete and the blocks.
  4. At the end of the blocks and the concrete, you can add a small amount of mortar before placing more blocks around along the ends of the circle that you drew earlier. Make sure that you are pressing the blocks against the ends of the first blocks that you placed. Continue doing this until you form a ring of blocks. From there, start another row of blocks by placing mortar on top of the first block layer until you reach a height of about one foot tall.
  5. Allow the entire fire pit to rest and set for about a week or so before using it or else you will end up damaging the fire pit if the mortar was yet to completely dry up.
  6. The last thing that you need to do is to place something that is flame-resistant inside the fire pit so that it will separate the concrete from the flames. You can line up some fire bricks inside the fire pit while forming a circle.

What do you put under a fire pit on concrete?

So, again, the safest way for you to make sure that your concrete is safe from getting damaged due to the fire pit is to put a flame-resistant material under the fire pit and just on top of the concrete so that it will act as some sort of protection between the flames and the concrete.

We recommend that you use fire bricks that are very resistant to fire. Again, line up a few bricks inside the fire pit until they are able to completely cover the concrete. But, if you don’t want to end up spending more money on bricks, you can also fill up the fire pit with at least 3 inches of gravel, which you can easily remove and replace every time you clean the fire pit. 

Sources:

https://www.hunker.com/13425458/how-to-build-a-fire-pit-on-concrete
https://www.quora.com/How-do-you-safely-build-a-fire-pit-on-concrete