An outdoor fire makes a great gathering spot on a summer evening (or virtually any time of year), so whether you’re making s’mores or just fire gazing, it's a great addition to the backyard. Today I get to work with my son, Russ, as we build a fire pit using concrete landscape blocks. Russ is a fifth-generation Dunn family member who works for the company in design and merchandising. You’ll be seeing more of him in future Dunn DIY posts.
If you’re constructing your fire pit in the summer, make sure you look up any restrictions your city or county may have on outdoor burns. Here in Seattle we have hot, dry summers that leave us prone to wildfires, so we often have burn bans in place during particularly scorched spells. This blog from the Seattle mayor’s office has information specific to our area. Before you get started, be sure to review Seattle Fire Department’s home fire safety website (which includes a helpful fire safety checklist).
We built this specific fire pit for Eastside Academy’s New Housing Program. This program serves homeless and vulnerable youth in our community who also attend Eastside Academy’s nonprofit high school, where they receive education, recovery support, mental health counseling, and mentoring (with campuses in Bellevue and Redmond).
Step 1: Get your supplies
This is a relatively simple project with a few basic materials, but stacked together—it makes for a pretty heavy load. All that gravel and cement can be difficult to transport and maneuver. If you’re here in the Seattle area, Dunn Lumber offers a $40 flat-rate delivery for all local orders. (You can even purchase everything you need online and schedule your delivery.)
Step 2: Find a site for your DIY fire pit
Find a relatively level spot to place your fire pit. To minimize fire danger, locate the site away from buildings, overhanging trees, and bushes. It might seem obvious, but a fire pit will create a lot of smoke during use, so keep in mind the windows of adjacent buildings (and whether the smoke is likely to fill their rooms). Be considerate of neighbors too, and how smoke, or late night conversation around the fire may impact them.
Step 3: Prepare the area
Place 14 of the Windsor Stone blocks on the ground in a circle. Leave a small gap between the blocks (we’ll speak more on this later.) After you have your circle, mark the ground on the outside of the circle with marking chalk. We used the purple color; it's the least permanent and washes or dusts away easily compared to other chalk colors.
Step 4: Dig the pit
Now remove the 14 blocks you laid out, and you’ll be left with the outside diameter of your fire pit clearly marked on the ground (it will be about four feet across). It’s time to break out the shovels! We removed the grass and top layer of soil to a depth of 2-3” inches. (Note: we piled the dirt we removed onto a tarp so we could easily drag it to another area later.)
Our ground was very hard and rocky, so before the shovels went in, we used a pick mattock to break up the ground. You might not know a pick mattock by name, so just picture the tool a prospector mining for gold uses. A pick mattock is a tool with a narrow pick on one side of the head and a more broad blade or “adze” on the other. You can break up hard soil with the pick or the adze. Bottom line: The pick mattock made the job a lot easier.
Step 5: Lay gravel for the base of your fire pit
Once we had our circle cleared to a depth of 2-3” inches, we spread some gravel around the perimeter. This creates a bed for the blocks, keeps things level, and also provides drainage. Next, we dug a hole about 18” deep and 18” wide in the center of our area, and filled it with coarse gravel. This deep hole is optional, but we chose to add it to increase drainage in the hard-packed soil surrounding our particular site.
Step 6: Arrange the cement blocks
Place three layers of blocks. Fair warning: this step requires some “in-the-field” adjustments, because the Windsor blocks have a lip on their bottom back side, which makes each successive layer step back from the layer below. That means each of the three layers has a slightly different (and diminishing) circumference as the fire pit continues upwards from bottom to top. For the most complete look, you’ll want the blocks on the top layer butted neat and tight. (Again, this means the middle layer is a slightly larger circle and the bottom layer a bit bigger still.) This will require you play around a bit with the blocks to get the spacing right. Check each layer with a level as you go to make sure it's reasonably flat.
Long story short, lay the bottom layer of 14 blocks with a bit of spacing between the blocks. Then, lay the middle layer of 14 blocks while staggering the seams between each block—so that it is oriented over the middle of the blocks below. Lastly, place 13 blocks as your top layer, and adjust the blocks as needed to get a neat, tight circle on the top. (You’ll have gaps between blocks on the bottom and middle layers, and that’s fine.)
Step 7: Secure the blocks with adhesive
Once you have the top layer arranged nice and tight, remove each block of the top layer one at a time, gun out some Loctite Premium Construction Adhesive, and replace the block (pressing it firmly into place).
Spread gravel inside the walls on the floor of the fire pit, being careful not to disturb your careful placement of the blocks until the glue has dried.
Step 8: Add a metal screen (Optional)
For extra safety, consider adding a 40" metal fire screen to your pit. We found ours on Amazon.
Along with deep fireside chats and stargazing, s’mores are quintessentially linked with a roaring bonfire. With Dunn DIY's recipe for homemade marshmallows and this one for ooey, gooey, melty s’mores (using our hometown favorite, Theo Chocolate), you can step up your fire pit game from flickering to blazing hot!