This post may contain affiliate links. If you click an affiliate link and make a purchase, I may earn a commission. Also, as an Amazon Associate I earn from qualifying purchases.
Building a cinder block fire pit is a simple do-it-yourself project. Simply look at the images below and decide for yourself how simple it is to construct one.
You may have Cinder Blocks or Concrete Blocks laying around your backyard. You could also find them on Craigslist, possibly for free.
Let me show you some ideas and plans for making a budget-friendly fire pit. The most affordable plan would rely solely on blocks.
If you’re willing to spend a little more money, you could use other types of outdoor stones or pavers to decorate or enhance the look of your pit. Which, in my opinion, is completely unnecessary.
How To Build A Cinder Block Fire Pit?
A cinder block fire pit is a very common type of outdoor fireplace. It’s easy to build and will add both charm and function to your yard or patio area.
The most commonly used material is cinder blocks. They are cheap and easy to find which makes them a popular choice for fire pits.
Cost Of Building A Cinder Block Fire Pit
The average cost to build a cinder block fire pit is between $40 and 60$.
Let us look at the costs breakdown:
A 16′′ L x 8′′ H x 6′′ W cinder block (with holes) starts at $1.15 at Home Depot and $1.13 at Lowe’s for the same size and shape.
The largest size block – 16′′ x 8′′ x 8′′ (with holes) – that most people use for fire pit projects costs just $1.37 per piece. A 16′′ x 8′′ x 4′′ Cap block costs only $1.55.
You can build your own or have one built by a professional if you so choose, but it’s really not that difficult of a process to complete on your own with the right tools and materials at hand.
Cinder block fire pit ideas range from basic designs using only four walls with an open-top to more complex ones that include seating areas around the base as well as covering over part of the structure in order to allow people who would like some time out away from the heat during colder months while still enjoying their outdoor space comfortable when warmer weather returns again.
In addition, there is usually no setup time involved with assembling a cinder block fire pit, and the structure is sturdy enough to hold up under most weather conditions.
Cinder Block Types
There are several different shapes and sizes to choose from (see image above). Those with through-holes are hollow all the way through. The remainder is solid blocks. Caps are the skinny ones with no holes (16′′ x 8′′ x 2′′).
Lowe’s 8-in x 8-in x 16-in Standard Cored Concrete Block is a popular choice. It costs $1.35, which is two cents less than the Home Depot price.
- Cinder Blocks are inexpensive and large, so it only takes a few to make a large fire pit at a low cost.
- Because they are so heavy, you don’t have to secure the blocks together. This makes assembly a breeze.
- They are widely available. Some will give them away for free in order to clean up their yard.
- They are not fire rated; instead, they are fire resistant. There is a significant difference. More on that debate can be found further down.
- They are not very aesthetically pleasing (when compared to other landscaping stones and bricks).
- It is difficult to construct a nice-looking round fire pit with these blocks. However, it is not impossible – see ideas below.
Check Out Our Other Calculators:
- Free Concrete Slab + Bags Needed Calculator
- Free Pea Gravel Calculator
- Free Picket Fence Calculator
- Patio Paver Calculator + Cost
Fire Resistant vs. Fire Rated
Cinder Blocks are fire-resistant, which means they will not burn, but they are not fire-rated, and prolonged and repeated fire exposure will cause them to crumble.
The National Masonry Association website – ncma.org – has more information on concrete masonry assemblies fire ratings.
TIP: I now understand why people fill holes in Cinder Blocks with gravel or crushed rocks after doing some reading on that site – it improves the fire rating of the blocks. So that’s a helpful hint!
If you read reviews, the general consensus is that they should not be used in fire pits because they are not fire-rated (see home depot reviews).
To protect the structural integrity of your pit, some people recommend placing a steel fire bowl or a fire pit ring on top. Others would use firebricks to line the pit. However, this would significantly increase the cost of your do-it-yourself project.
But, hey, you’re making a low-cost firepit out of free or recycled blocks. Expectations should be kept low.
How To Build A Cinder Block Fire Pit
The materials you will need for this project are cinder blocks, mortar, and a few tools. Cinder Blocks not only can be used to build fire pits but also any other structures such as steps or benches.
Step-by-step instructions on how to build a cinder block fire pit.
Follow the steps below that show you how to create this simple outdoor masterpiece in minimal time and cost!
1. Gather Materials
Materials needed are as follows – Cement, Mulch (optional), Sand (optional), Barbecue Grill (optional). Note: You can use any type of grill for this project.
2. Layout and Cut Blocks
Using a tape measure, layout your cinder blocks in the shape you want to build your fire pit or barbecue. Then use a hand saw or masonry knife (if they are not square) to trim off any excess material on the edges of the blocks so that all sides will be even when placed next to each other.
3. Prepare Cement Mix
Make sure you have enough cement mix for at least two bags per block section as well as sand and water if using mortar and grout instead of plain concrete mix with just gravel aggregate added per bag instructions.
(If the wall is under 24″ inches high do not fill more than three-quarters full). To make enough mix for one section will require two bags of ready-mix concrete, four to six quarts of sand, and about five inches deep of water.
4. Mix Cement
Mix the cement with a shovel or hoe until it is well blended then add more dry material gradually while mixing in some water at a time just enough so that you have good consistency without any lumps.
If using mortar instead, blend all ingredients together before adding small amounts of water as needed to get a proper mixture. (Water should be added sparingly because too much can cause cracking).
5. Prepare Fire Pit Foundation
Start placing blocks on the bottom row (at least three) working across each block facing up toward the top center where they are joined. Be sure to make a nice level bed across all fire pit layers.
(Blocks should be placed with the flat sides and ends touching each other and their joints staggered by at least one-half block length.)
6. Fill Fire Pit Layer One
Using mortar, start filling in the next layer starting from the center bottom of blocks working toward the top or end then fill in the middle using concrete mix without gravel aggregate.
Finish this layer off before moving on to the third layer. (To prevent cracking do not add water while mixing cement; instead, wait until the layering process is finished).
7. Fill The Third Layer With Mortar And Grout
Fill the last two rows with mortar and grout mixture if desired for decorative appearance. (If making a barbecue place grill on top after filling final layer).
8. Clean Up
Clean up excess grout or mortar from blocks with a wet sponge before it dries. You can also use a wire brush to lightly scrub off any remaining cement mix stuck in the crevices of the block.
(Fill pit level full before adding any type of fuel, then wait for the fire to start burning and flames have turned into glowing embers.)
Burn your new cinder block fire pit by placing dry wood down slowly building the size of all the pieces gradually larger as they burn away creating coals that will last several hours without needing more wood until you are ready to go home.
10. Grill (optional)
Place barbecue grill on top of finished product and enjoy cooking a meal over a nice bed of coals especially if using charcoal instead of wood so there isn’t any smoke from burning logs.
(You can also place pre-charcoal in center bottom first then add chunks along sides.)
How to Join Cinder Blocks Together?
Using a cinder block is convenient, but they can easily be separated. This doesn’t have to be the case when you need them for a specific project or building because there are ways that you can use these blocks together. Here are some of the best methods:
- By using mortar and cement
- By drilling through all of the rows
- By filling in around each row with smaller pieces after it has been laid out
Is it necessary to glue the blocks? You don’t have to – they’re heavy enough to stay put as long as no one tries to push them apart on purpose. However, if you have small children, it is safer to glue them together.
Based on my research, I discovered two adhesives that would be ideal for connecting Cinder blocks when building a firepit: Liquid Nails FuzeIt and Quikrete Fireplace Repair Mortar. In the store, a good question to ask is which one holds up better near the fire.
13 Great Cinder Block Fire Pit Ideas
So roll up your sleeves and prepare to put in some elbow grease because we’re going to show you 13 amazing cinder block fire pit designs to inspire your own.
This cinder block fire pit appears to be an indoor fireplace! We adore the grate and the pebbles that surround it. It’s ideal for sitting outside on a summer evening and roasting marshmallows.
Decor And Fire Pit
The treeline in the background casts a lovely evening shadow, allowing you to start your fire earlier! We adore the landscaping that surrounds the beautifully crafted cinder block structure.
Big Daddy Fire Pit
This solid-looking cinder block fire pit has a large air inlet at the bottom to ensure that the fire can roar! This is good news, given the size of the logs in the background.
The lava rocks complement the geometrically pleasing concrete block fire pit. We don’t know what kind of cinder blocks they used, but the result was a very smooth exterior. There’s also plenty of room for your cold beverages!
If you like what these people have done here, there is a similar-looking free-standing gas fire pit on Amazon that you might be interested in (here’s the link if you’re interested).
The red brick at the base of this fire pit is particularly appealing to us. It’s still a mystery how the creator got the cinder blocks to be that unusual shade of green, but the results are undeniable.
The Backyard Beast
We’re not sure if this is a do-it-yourself fire pit or not — the craftsmanship appears to be excellent. We’ll give the creator the benefit of the doubt, but it’s clear that he or she can do amazing things with his or her hands. The color is also pleasing to the eye and makes the lawn around it stand out.
The Paver And Cinder Block
Here are a few more DIY projects and plans made from cinder blocks and paver bricks.
To improve air intake, use blocks with through holes on the bottom.
To reduce the heat effect on the concrete blocks, place some pebbles or landscape rocks on the bottom.
The below design is made entirely of concrete block caps. It’s the best design I’ve seen so far – a quick and easy assembly made of uniform bricks.
Level the surface with gravel then lay out the caps and you’re done. Caps are a few cents more expensive than blocks. We’re only talking about a couple of dollars here.
This design employs skinny blocks on top to create an eye-catching oversized fire pit.
2 DIY Cinder Blocks Plans FREE
Cinder Block Fire Pit Under $40
The original design, as well as some guidelines, can be found here. It’s worth noting that the image there says they used 24 blocks, but I believe this is an error. There are a total of 28 blocks required for this project: 8 for the base, 8 for the top, 8 for the outside frame, and 4 for the inside supports (one on each side). And the notes back this up.
According to the DIY designer, all supplies were purchased from Lowe’s and the project took about 3 hours to complete.
It’s a good-sized square pit. They used fire-resistant concrete Caps (shown below), which are available here. More detailed instructions on how to build it can be found here.
What other people made using the above instructions and photos is shown below. Some claim to have spent even less than $40. There are as many DIYers as there are ideas.
Easy Movable Cinder Block Fire Pit
According to the designer, the above-shown fire pit plan requires 8 cinder blocks ($1.45 each), 8 cement caps ($.95 each), 2 bags of lava rock ($2.75 each), and optional 1-foot square pavers ($3-ish). There won’t be much for you to do. This is one of the quickest and most affordable plans we’ve seen. You would level the ground, place the blocks, place caps on top (to cover the holes), place lava rocks in the pit, and finish with a few pavers.
Is Cinder Blocks Safe For A Fire Pit?
We recommend using cinder blocks that are fire-rated. You don’t want to use a block that is too compacted in a fire pit.
It must be porous enough to allow steam to escape as trapped water transforms into steam. If blocks aren’t permeable, they might blow up when the pressure inside builds up owing to the accumulation of steam.
Do You Need A Liner For a Cinder Block Fire Pit?
There are many different options for building a fire pit. One option is to use cinder blocks as the foundation of your outdoor fire pit.
If you have chosen this route, then you should seriously consider using an insulating material between the outside wall and the first layer of blocks so that heat doesn’t escape through gaps in mortar lines.
Using a liner will also help prevent moisture from seeping into materials used inside or around your block foundation which can lead to an explosion.
Are Cinder Blocks Heat Resistant?
Cinder blocks are heat resistant. However, this does not mean that they will be completely safe if exposed to extreme heat for a prolonged period of time. Cinder blocks can crack if exposed to extremely high temperatures or flames over an extended timeframe.
The cinders inside the block are pressed together tightly by mortar which prevents them from breaking apart easily when heated up – but do not mistake that as complete resistance to fire damage!
Will Cinder Blocks Explode In a Fire Pit?
Yes, they can. When cinder blocks are not porous, they can explode as the steam builds.
When cinder blocks aren’t porous, water can be absorbed into the material and then released when heated again which will negate any pressure that would lead to an explosion.
How Long Does Cinder Blocks Last In A Fire Pit?
Cinder blocks are a cheap alternative to building materials. They are strong enough for structural elements, but can also be used in less demanding residential applications such as fire pits and planters.
Cinderblocks have been known to last up to 50 years or more if they were not exposed to water when originally constructed, the mortar is still intact, there was no damage during construction that allowed moisture leakage into the brick itself, etcetera.
The following chart outlines how long cinder blocks generally last based on their use:
Firepit = approx 15-20 years with little maintenance required.