Blocks used to make retaining walls not only make a great looking diy fire pit, but they also have relatively easy installation. Depending on your design, this is a project you could start in the morning and have a campfire burning in it by afternoon.
Find out how many retaining wall blocks you will need to build your own fire pit, along with other tips in the post below!
How Much Wall Block You Need for a round Fire Pit
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There are a few common sizes of trapezoid pavers: 8″x 3″x 4″, 10.25″x 3.5″x 7″, and 11″x 4″x 6″. The table below shows how many of each type of block you would need to get the size of fire pit you want to build.
The estimates given below are for a fire pit that has 4 layers of wall blocks, as shown in the photo below.
If you want more or less layers, simply divide the number given below by 4 and multiply by the number of layers you would like.
Number of Wall Block Needed to Build a Fire Pit
What is nice about wall block fire pits is that you usually have easy access, they are simple to build, and they don’t require mortar, fire brick, or pit liners, if you want to keep your pit as easy and inexpensive as possible.
Plus, there are so many colors and styles of wall brick available, you will easily be able to find one to fit the look you are going for.
Fire Pit Brick & Block Calculator
If you are in the planning stages of your backyard fire pit and still not positive what kind of material you would like to use to make it, take a look at our Fire Pit Brick & Block Calculator.
It features many common sizes of bricks and blocks available at home improvement stores.
Select the diameter you would like your fire pit to be and the number of layers you would like to build, and it will offer an estimate of the number of bricks or blocks needed.
Using retaining wall blocks with a lip on the bottom
Some retaining wall blocks come with a 1″ lip on the interior side of the bottom of the block.
This lip is used to help secure and align the block when building walls.
These kinds of retaining wall blocks can definitely still be used for your fire pit walls as well, but you just need to be aware of how this lip will affect the design of your diy fire pit.
Rather than each new row of block fitting perfectly on the last, these lipped retaining wall blocks will recess in 1″ on every new ring.
As you can see from the photo above, these lipped retaining wall blocks can still make very attractive pits.
This inset of every row will need to be taken into consideration when determining the inner diameter of your pit, especially if you are planning on using a fire pit liner, like the one in the picture above.
Make it easy on yourself and have high-quality steel fire pit liners from Titan Great Outdoors, with or without a built in cooking grate, shipped right to your door. Click here to see their current selection.
Using Mortar in your Retaining Wall Block Fire Pit
Mortar is optional when building a fire pit made from retaining wall blocks as these blocks are designed to be stacked into a sturdy wall with no mortar to hold it together.
However, if you like the rustic lodge feel that mortar adds to a fire pit, you could choose to use that, as well.
When using mortar, this will typically add around .375″ to every joint.
That will need to be figured into the design of your fire pit.
For a high heat area, such as a fire pit, refractory mortar, otherwise known as refractory cement should be used.
Refractory cement comes in a bucket, is premixed, and ready to use.
If you don’t live near a hardware store, you can find this high-heat mortar online here.
A soft-bristled brush can help wipe off excess mortar and clean up the look of your joints in your retaining wall fire pit.
Extending the life of your wall block fire pit
Just because with retaining wall blocks you have the option to simply stack the stone and be done in an hour doesn’t mean that you can’t put a little more effort and investment in to make your fire pit look a bit more polished and extend its life.
There are 2 ways to do this, fire brick or a fire pit liner.
Fire brick is designed to hold up to high heat environments, like inside your fire pit walls.
These are typically only used to line the inside of a diy fire pit and are then covered with a more decorative material, like wall block.
Fire brick is typically installed in a fire pit with the long side going up and down.
They can be set inside your pit dry and get the job done. Just know that they will shift as the ground shifts and will need to be readjusted periodically.
Typically, fire bricks are installed in a fire pit using refractory cement as mortar.
Refractory cement is also designed to hold up to high heat.
This could be done in conjunction with a dry-laid retaining wall block fire pit that doesn’t utilize mortar, but adding mortar to your entire fire pit would give it a more polished and permanent appearance..
Fire pit insert
A steel fire pit liner, can also be used in a retaining wall block pit fit to extend the life and give the pit a more finished appearance.
Fire pit liners only come in specific sizes so you will need to purchase a liner before you begin your fire pit project.
Custom sized inserts can be found and purchased online, but this adds to the cost.
Titan Great Outdoors offers high quality fire pit liners in sizes that will fit retaining wall block fire pits with interior diameters of 27″, 32″, or 42″. They are 10″ tall and have a 6″ lip on the top that helps to hold the ring in place.
See what Titan Great Outdoors currently has available on Amazon here.
How to prepare the ground for your wall block fire pit
We preach about proper preparation of the ground before building a fire pit or any type of wall or patio.
The ground WILL shift, and if you live in a climate that freezes, this will happen more sooner than later!
However, what is nice about wall block fire pits is that you could skip much of the prep in your fire pit area if you are dry-laying your pit (not using mortar).
If you simply want to grab some wall block, throw down a few rings on the grass, and have a fire in it immediately, with retaining wall blocks you can absolutely do that.
This is perfect if you don’t want the fire pit there permenantly as you can easily pick up the blocks and move them later, just leaving a burnt place in your yard, obviously.
Even if you would like to keep your wall block fire pit where it is for a few years, you can still just dry-lay it, knowing that you may have to pull some or most of the blocks off at some point and reset them after they have shifted and look uneven.
But, with wall block you have the option to do that.
Definitely properly prepare the ground for your retaining wall fire pit if using mortar on any parts of your pit, however.
Shifting ground and mortared blocks are a waste of time and money, so do take the time to prep your fire pit area if using mortar.
What to put in and around your fire pit
A retaining wall block fire pit could just be set on the ground, but there are other materials that could be used inside a fire pit.
Gravel, lava rock, dirt, sand, or a layer of refractory cement are common materials used at the bottom of a fire pit.
Avoid pea gravel as they can have air pockets inside that could explode when exposed to high heat.
You have more choices when it comes to what to put around the outside of your fire pit.
Any fire-resistant material would work, including all of the ones listed above, plus cement, pavers, and flagstone. Of course, nothing is also an option if you are wanting to keep things simple.
Avoid wood mulch as it could easily become a fire hazard when embers land on it.
Another great option for the area around a backyard fire pit are pavers like the ones shown below.
They are modular and easy to install, but the irregular shapes and crevices that allow for sand and grass give you the look of a natural material.
Hopefully now you have the the information you need to build your own fire pit, prep your fire pit area, and know if you need to use mortar or fire pit bricks in your build.
And if this seems like something you don’t want to tackle, you can always purchase a fire pit kit available at many hardware stores where all parts are included and ready to go.
* As an Amazon Associate I earn from qualifying purchases.
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You may also enjoy our other articles:
When to Use Fire brick in a Fire Pit and When to Skip It
How Many Brick Pavers You Need for a Fire Pit