Building a fire pit with retaining wall blocks

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Wall block not only makes a great looking fire pit, but it is also a material that is relatively easy to build and work with. 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 wall blocks you will need to build your fire pit, along with other tips in the post below!

How Much Wall Block You Need for a Fire Pit

There are a few common sizes of trapezoidal wall block: 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 block, 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.

What is nice about wall block fire pits is that they are so simple to build and don’t require mortar, fire brick, or fire inserts, 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.

Using retaining wall blocks with a lip on the bottom

Some retaining wall block comes 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 blocks can definitely still be used for fire pits, but you just need to be aware of how this lip will affect the design of your 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 fire 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 Wall Block Fire Pit

Mortar is optional when building a fire pit made from wall block 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. One bag of 60lb. mortar mix should be enough for most sized fire pits.

Mixing your mortar is most easily done in a wheelbarrow. A garden hoe can be used to mix the mortar and a masonry trowel can be used to apply the mortar between your wall block. A soft-bristled brush can help wipe off excess mortar and clean up the look of your joints.

Extending the life of your wall block fire pit

Just because with wall block 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 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

Fire brick is designed to hold up to high heat environments, like inside your fire pit. These are typically only used to line the inside of a 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 brick is 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 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 if using wet-laid fire brick.

If you’re struggling to find fire brick and refractory cement around where you live, you can have them shipped right to you. Find fire brick here and refractory cement to order here.

Fire pit insert

A steel fire pit insert, also known as a fire pit liner, can also be used in a wall block pit fit to extend the life and give the pit a more finished appearance.

Fire pit inserts only come in specific sizes so you will need to purchase a liner before you begin your fire pit project. Custom sized fire pit inserts can be found and purchased online, but this adds to the cost.

Titan Great Outdoors offers high quality 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 this step 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 wall block 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 you 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 area if using mortar.

What to put in and around your fire pit

A 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 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.

Fire Pit Brick & Block Calculator

If you are in the planning stages of your 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.

* As an Amazon Associate I earn from qualifying purchases.

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