How to Build Your Own DIY Outdoor Fireplace

I spent a whole October convincing myself the backyard was fine as it was. The flower rows were wrapped up for the season. My two dogs had already dug up the garlic bed. That part was decided for me.

But every evening around six, the light dropped, and the air had that first real bite of fall.

I kept standing at the back steps. Something was missing.

It wasn’t a garden problem. The garden was good. It was a staying outside past dark problem. And the only thing that fixes that is fire. I’d been going back and forth between a fire pit and an outdoor fireplace for two seasons.

A fire pit made sense on paper, but I wanted something that looked like it belonged there. Not just a ring I could carry off in a truck. A fireplace has weight to it.

It gives the backyard a reason to exist even on the nights you don’t light it.

This guide covers design styles, a full step-by-step cinder block build, materials, and costs. By the end, you’ll know which build fits your backyard, your budget, and your skill level.

Why a Fireplace Beats a Fire Pit (For Some Backyards)

Choosing between a fireplace and a fire pit comes down to how you want your outdoor space to function. Both create warmth and a gathering spot, but they serve very different purposes.

A fire pit offers flexibility. It is easier to install, costs less, and creates a casual seating area where people can gather from every direction. It is also a better choice for renters or anyone who may want to change their backyard later.

A fireplace is a more permanent feature. It becomes part of the landscape design, height, and a visual anchor even when no fire is burning. Unlike a fire pit, which can feel temporary, a fireplace looks intentional year-round.

If you want a backyard feature that feels built-in and permanent, a fireplace may be the better investment. If you want something simple, flexible, and easy to change, a fire pit is likely the smarter choice. 

The right option depends less on which one is better and more on how you plan to use the space.

Questions Worth Answering First Before You Start

These are the things I wish I’d sorted out before pricing materials.

1. Check local codes and HOA rules first: Most municipalities require 10 feet of clearance from structures and property lines. Some areas ban open wood fires entirely. Permits for wood and gas builds usually run $50–$500.
2. Pick your fuel type before picking a location: Wood is atmospheric but needs a chimney, seasoned hardwood, and dry storage. Electric needs only an outdoor outlet and skips structural fireproofing entirely.
3. Think about wind direction: Figure out which way the smoke blows before you decide which way the opening faces. Smoke aimed at seating areas or toward the house ruins the whole thing fast.
4. Plan the foundation: Any permanent cinderblock fireplace requires a concrete pad. It should be at least 4 inches thick and reinforced with steel. Don’t pour directly on soil.
5. Sort out firewood storage: Only burn dry, seasoned hardwood: ash, maple, and oak burn hot and clean. Never burn treated lumber. Plan where the wood lives before you start, not after.

Tools and Materials for Your DIY Fireplace

Sizes vary, but a typical DIY outdoor fireplace runs about 7 feet wide, 2 feet deep, and 7–8 feet tall.

Materials:

• Cinder blocks (CMUs): for the main structure
• Firebrick: for the firebox interior lining
• Type N mortar: for above-ground block laying
• Type S mortar: for foundation-level blocks (stronger mix)
• Refractory mortar: for setting firebricks (heat-resistant)
• Rebar and wire mesh: for the concrete foundation
• Concrete mix: for the foundation pad
• Steel lintel: to span the firebox opening
• Clay flue liner or metal chimney: for the chimney stack
• Chimney cap with spark arrestor: for the top
• Stucco mix and masonry paint: for the exterior finish

Tools:

• Masonry trowel and pointing tool
• Spirit level
• Rubber mallet
• Circular saw with masonry blade
• Drill with a masonry bit
• Mixing tub or wheelbarrow
• Tape measure and chalk line
• Safety gloves and eye protection

How to Build a DIY Outdoor Fireplace Step by Step

This is the full cinder block build, the most common DIY method. It gives you the most control over the finished result. Budget two to three weekends from foundation to veneer.

Step 1: Check Local Codes and Mark Your Location

Check your local building codes before you touch a shovel. Most areas require 10 feet of clearance from structures, fences, and property lines. Some require a permit for any wood-burning structure.

Once you’re clear on the rules, pick your spot. Look for level ground, away from overhanging trees and covered structures. Think about the prevailing wind.

Mark the foundation area with stakes and chalk lines. Double-check the corners are square by measuring across the diagonals.

Step 2: Pour the Concrete Foundation

Dig down 6 to 8 inches across the marked area. Fill the bottom 4 inches with compacted gravel for drainage, then tamp it flat. 

Build a wooden form around the perimeter to hold the concrete pour.

Lay rebar in a grid pattern inside the form and add wire mesh for added strength. Mix and pour concrete to fill the form, smooth the top with a magnesium float, and check for level. 

Allow the foundation to cure for at least 72 hours; 5 to 7 days is better. Don’t rush this step. A cracked or uneven foundation causes problems at every stage after it.

Step 3: Lay the First Course of Cinder Blocks

Spread a layer of Type S mortar over the cured foundation, then set your first course of cinder blocks. Start at a corner and work outward. 

Keep the center open for the firebox, lay blocks in a U-shape, open at the front.

Use a level on every block as you go. Check for plumb vertically and level horizontally after each one. Use a rubber mallet to tap blocks into position before the mortar sets. 

Don’t skip the level checks. A small error on the first course gets worse with every row you add.

Step 4: Build Up the Walls and Firebox

Stack additional courses of cinder blocks, staggering the joints as you go, like bricklaying. Staggered joints give the structure strength.

Apply mortar to the top and sides of each block before placing the next.

Use a level frequently as the walls rise. A standard firebox opening runs 36 to 44 inches wide and 24 to 30 inches tall. It should be at least 20 inches deep. 

These proportions help the fire draw properly and keep smoke from spilling forward.

Step 5: Install the Steel Lintel

The lintel is a steel angle bar. It spans the front of the firebox opening and supports the block courses above. Cut or buy the lintel to size. 

It should extend at least 4 inches past each side of the opening.

Lay it across the top front edge of the firebox. If it’s not perfectly level, use coins or sand as shims until it sits flush.

Once positioned, continue laying blocks on top of it to build the structure above the opening.

Step 6: Line the Firebox With Firebrick

Regular cinder blocks can’t handle the direct heat inside a working firebox. Firebrick can.

Use refractory mortar, not standard mortar, to set firebricks along the floor and interior walls of the firebox. Work in a staggered pattern for stability.

Apply the refractory mortar in joints no thicker than 1/4 inch. Thicker joints trap air, which weakens the bond under high heat. 

Allow the firebox lining to cure fully before lighting any fire inside. This step is what protects the structure in the long term.

Step 7: Build the Chimney

Continue stacking cinder blocks above the firebox in a running bond pattern to form the chimney flue. Keep all four sides plumb; use a level on every course. 

The flue opening should match the proportions of the firebox opening below it.

The chimney needs to be cleared of any structure within 10 feet by at least 2 to 3 feet. This height creates the draft that draws smoke up and out.

Short chimneys produce smoke problems in the seating area. Plan the height before you start the build, not after.

Step 8: Install the Chimney Cap

Fit a prefabricated chimney cap over the top of the flue. 

The cap keeps rain, birds, and debris out of the chimney. It should include a spark arrestor: a mesh screen that stops hot embers from escaping.

A spark arrestor is required by code in most areas for wood-burning fireplaces. Even where it isn’t required, it’s a good idea. Embers landing on dry grass or a wood deck are a bad way to start the season.

Step 9: Apply the Exterior Finish

Allow all mortar to cure fully, at least 24 to 48 hours, longer in cold or humid weather. 

Then apply your chosen exterior finish. For stucco, apply in even layers with a trowel. Let each coat dry before adding the next.

For stone veneer, use masonry adhesive and press each piece firmly into place. Work from the bottom up. 

For painted finishes, use exterior masonry paint rated for heat exposure. The finish is what turns a concrete block structure into something that actually looks like a fireplace.

Step 10: Cure Before First Use

Before lighting the first fire, let everything dry for at least 72 hours. Check the firebox for any cracks in the mortar or firebrick joints and seal them with refractory mortar before use.

Light a small, low fire for the first couple of burns to allow the mortar to cure gradually in the heat. Don’t go straight to a full blaze. Rapid heat on fresh mortar can crack joints that would otherwise hold for years.

You can also design your garden around the fireplace to create a more balanced and visually appealing outdoor space.

DIY Outdoor Fireplace Ideas by Style

The style you choose will affect material costs, the required skill level, and how the finished structure looks year-round. These are the most common builds, with honest notes on who each one suits.

• Stucco Over Cinder Block: A popular DIY finish, stucco creates a durable, paintable surface over concrete blocks. It suits modern and Southwest styles and is ideal for beginners.
• Stacked Stone Veneer: Stone veneer adds a classic farmhouse or cottage appearance over a cinder block base. It delivers a natural stone look without masonry costs.
• Fiber Cement or Shiplap Cladding: This modern finish uses fiber cement boards installed over a framed structure to create clean lines. It offers durability, weather resistance, and contemporary style.
• Brick: Brick fireplaces provide timeless appeal, strong durability, and excellent resale value. They require more effort and cost but suit traditional home styles beautifully.
• Mixed Stone and Wood: Combining stone around the firebox with a wooden mantle creates a warm indoor-outdoor feel. It adds customization while balancing durability and character.
• Fireplace With Built-In Log Storage: Integrated log storage keeps firewood organized, dry, and nearby. Adding this feature during construction is easier than modifying the fireplace later.

What It Actually Costs

The honest answer: it depends almost entirely on which method you choose and how you finish it.

What I Learned From Planning Mine

I went back and forth for two seasons before I picked an electric insert in a wood frame.

I could probably have handled the cinder block method. But I wanted to finish it in a weekend and had no interest in pouring concrete in November.

The frame went up on a Saturday morning. My husband handled the insert while I cut the paneling. 

We used tongue-and-groove boards for the cladding and painted everything dark charcoal. It went against the back fence near the garden. It looked right from the first evening we lit it.

What I’d do differently: plan the firewood storage from the start. I have a stack of oak sitting in a corner with nothing covering it, and that’s fine until it isn’t.

A side compartment built in from the beginning would have solved that in an afternoon.

The other thing: I didn’t think through seating enough. The fireplace is in the right spot. The chairs weren’t the right distance. I spent the first few evenings shuffling them around before settling on what worked.

If you’re building from scratch, plan the seating layout at the same time as the fireplace placement.

Conclusion

A DIY outdoor fireplace is one of those projects that sounds bigger than it is. 

Ten steps for the full cinder block build. A weekend for the electric insert method. Either way, you end up with something that changes how you use the backyard from October through April.

Whatever method you choose, sort out local codes, pick your fuel type, and get the foundation right before anything else. Those three decisions shape everything that follows.

And figure out your seating before you pour a single bag of concrete. I’m still moving chairs around on this farm, and the fireplace has been up for two years.

Frequently Asked Questions

What Is the Easiest DIY Outdoor Fireplace to Build?

An electric insert in a wood-framed surround is the most beginner-friendly option. No masonry, no gas line, no permit in most areas. Two people can finish it in half a day.

How Many Cinder Blocks Do I Need for a DIY Outdoor Fireplace?

A standard 7-foot-wide, 8-foot-tall fireplace uses roughly 150 to 200 cinder blocks, depending on the design and wall thickness. Always buy 10 to 15 percent more than your estimate to allow for cuts and breakage.

Do I Need Firebrick Inside a Cinder Block Outdoor Fireplace?

Yes. Regular cinder blocks crack under the direct heat of a firebox. Firebrick is rated to handle extreme temperatures without failing. Line the all interior walls of the firebox with firebrick and use refractory mortar.

How Tall Does an Outdoor Fireplace Chimney Need to Be?

The chimney should clear any structure within 10 feet by at least 2 to 3 feet. This height creates the draft needed to pull smoke up and away. A chimney that’s too short causes.