Watch the Full DIY Build: The Barrington Outdoor Fireplace Assembly

A Professional-Grade, Solid-Masonry Build You Can Finish in a Weekend

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Building a professional-grade masonry fireplace doesn’t require a master mason, messy mortar, or dangerous stone saws. By using a solid-block, pre-cut system, any DIYer can create a permanent backyard feature in a single weekend. Here is the engineering logic and the step-by-step process to ensure your build is a success.

Stop worrying about messy mortar or complex stone cutting. This video walks you through the “Cornerstone Way”—a clean, modular system that turns a stack of blocks into a permanent backyard feature. Unlike thin-veneer kits, we use solid-block construction. It’s engineered to be easy enough for any DIYer to finish in a weekend, providing a professional result without the professional masonry price tag.

Project Duration: Weekend

Project Difficulty: Intermediate

You Will Need:

  • 4ft & 2ft Levels
  • Dead Blow Hammer (Essential for “locking” wedges)
  • Caulk Gun (High-quality)
  • Metal Tape Measure
  • 6ft Ladder
  • Electronic Leaf Blower (For cleaning blocks)
  • Instructions

Video Timeline

Timestamp

Step

Description

00:53

Squaring the Footprint

Use the "Arc Method" with a non-stretching metal tape measure to pull off a fence or house.

02:22

Wedge Block Basics

Understand the small, medium, and large wedge units. They create 6 different face sizes.

04:56

The Critical First Course

Leveling front-to-back, side-to-side, and crossways. This is the most important step.

09:31

The Hearth Safety Hook

Glue the ends and sides of the hearth blocks specifically to handle weight/sitting.

10:23

Firebrick Strategy

Start your firebrick from the front and work back. Ignore the corner gap.

12:26

The Lintel Step

Use angle iron to span the firebox. Use coins or washers as shims if it isn't flush.

13:54

The Support Column

Build a temporary column of block to catch the front edge of the lintel blocks.

16:00

The Smoke Chamber "Finger Trick"

Use your finger and thumb to lock in the setback distance on both sides of the rack.

17:44

Counterweighting the Mantel

Use extra blocks to counterbalance the weight of the mantel blocks so they don't tip.

22:54

Trimstone & Cap

Flip the "best-looking" side of the capstones downward so they look great from the patio.

Pro Tip:

The Leaf Blower Secret: These blocks come from the factory with a fine masonry dust. If you don’t clear it, your adhesive will bond to the dust, not the stone. Use an electronic leaf blower to blast the pallet before you start stacking. A clean block is the secret to a permanent, 50-year bond.

The Cornerstone Way: Building Your DIY Outdoor Fireplace

Phase 1: Planning and Squaring the Footprint

The foundation of a great build starts before the first block is even set. While you might be tempted to just “eye” the placement, squaring your fireplace to your house or patio is essential for a professional look.

The Arc Method: If you are pulling measurements from a fence or wall, use a non-stretching metal tape measure. Create two five-foot arcs in the dirt or on your pad using a nail or pencil. By pulling a string line across the peaks of these two arcs, you establish a perfectly parallel line to your reference point at any distance.

Phase 2: Understanding the “Wedge” Block System

Unlike standard rectangular blocks, our kits utilize a series of small, medium, and large wedged units. This engineering choice gives you six different face lengths, allowing for a natural, rustic masonry look without any custom cutting.

  • Pro Tip: Even though they are wedges, you can run a perfectly straight line by simply alternating the direction of the wedges as you lay them. Because they are tapered, they “lock” together when tapped with a dead-blow hammer.

Phase 3: The Critical First Course

I cannot overemphasize this: The first course is the most important part of the build. If you are off by a 1/16th of an inch here, that error will grow into a major problem by the time you reach the chimney.

  • Meticulous Leveling: Lay your entire base course before you start leveling. Level every block front-to-back, side-to-side, and crossways.

  • The Dust Secret: Masonry blocks come from the factory with a fine dust. Use an electronic leaf blower to blast the pallet and the blocks before you apply adhesive. If you glue a dusty block, you are bonding to the dust, not the stone.

Phase 4: Building the Hearth and Firebox

Once the base is level, the build moves fast. As you stack, check for “Plumb” every three courses to ensure your walls aren’t leaning.

  • Hearth Safety: When installing the hearth, apply adhesive to the bottom and the sides of each block. Since people will be sitting or standing on this ledge, we want it structurally over-engineered.

  • Firebox Lining: When installing your firebrick, start from the front and work toward the back. You will notice a small gap in the back corners—ignore it. Overlapping the firebrick creates a thermal seal that makes the corner void irrelevant.

Phase 5: The Lintel and Smoke Chamber

The most technical part of the build is the Lintel Install—the steel support that allows for the wide firebox opening.

  • The Flush Test: Lay a 4-foot level across your lintel blocks. Look underneath; there should be zero gaps between the level and the lintel shelf. If it’s not flush, use coins or washers as shims to get it perfect.

  • The Support Column: While the glue cures on the blocks spanning the lintel, build a temporary “dummy column” of block to catch the front edge of the middle stones. This prevents sagging and is easy to knock out once the structure is weighted down.

Phase 6: Racking the Smoke Chamber (The “Finger Trick”)

To create the “rack” or the inward step-down of the smoke chamber, you need to be consistent on both sides.

  • Jake’s Finger Trick: Instead of struggling with a tape measure on tumbled, rounded corners, use your hand. Lock your thumb against your finger to set the distance of the setback on one side. Move to the other side and use the same hand-span to match it. It’s faster, more accurate, and ensures a centered chimney.

Phase 7: The Chimney and Finishing Touches

As you move into the chimney, watch for “twisting.” Use your 4-foot level vertically on the corners and crossways on the faces to keep the build straight and plumb.

  • The Final View: When installing the Trimstone and Cap, remember that people will be looking up at them from the ground. Flip the “best-looking” side of the capstone downward. If a block has a chip or a rustic edge, rotate that toward the inside where it will be hidden from view.

Further Reading:

Master the Full Project: Watching the build is only half the battle. To ensure your fireplace lasts a lifetime and meets local standards, use these essential resources:

  • Plan Your Patio in Scale. Use this to visualize the Barrington’s footprint within your specific patio layout and furniture arrangement using our Scaled Design Guide.
  • Foundation First: This build was performed on a pre-set gravel pad. If you haven’t prepared your site yet, watch our Foundation & Layout Tutorial to lay the groundwork for your kit.
  • The Finish Line: Once your adhesive has cured, you’ll need the right accessories. Browse our Fireplace Grates & Gas Log Sets to find the perfect match for your Barrington build.

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