Build A Outdoor Fireplace With Cinder Block

Building an Outdoor Fireplace with Cinder Blocks

An outdoor fireplace can be a fantastic addition to any backyard, providing warmth, ambiance, and a focal point for gatherings. With its rugged and rustic appeal, a cinder block fireplace offers a cost-effective and readily accessible option for homeowners. Building a cinder block fireplace requires careful planning, preparation, and execution, but the process is achievable for DIY enthusiasts with basic construction skills.

Choosing the Right Cinder Blocks

Selecting the appropriate cinder blocks is fundamental to the structural integrity and aesthetic appeal of your fireplace. Standard 8x8x16-inch cinder blocks are a common choice, offering a balance of strength and affordability. However, consider these factors for optimal performance:

Type: Choose solid cinder blocks over hollow blocks. Solid blocks provide greater structural stability, especially when exposed to high temperatures.
Material: Concrete blocks are the most common and durable option. However, if a more rustic look is desired, consider using natural stone blocks.
Color: Cinder blocks are typically gray, but they are available in a range of colors to complement your backyard design.

Constructing the Foundation

A strong and level foundation is crucial for a stable and safe fireplace. Follow these steps to create a foundation:

Determine the Size: Plan the desired dimensions of your fireplace and allow for a 6-inch perimeter around the firebox for stability.
Excavate the Area: Dig a hole that is at least 12 inches deep and slightly wider than the fireplace footprint.
Lay a Gravel Base: Fill the hole with 4 inches of compacted gravel to provide drainage and support.
Pour Concrete: Mix and pour concrete into the hole, leveling it carefully to create a solid base for the cinder block structure.
Curing: Allow the concrete to cure for at least 24 hours before proceeding with the construction.

Building the Firewall and Firebox

The firewall and firebox are the core components of your fireplace. Constructing these with cinder blocks requires precision and attention to detail:

Firewall: Using mortar, lay the cinder blocks around the perimeter of the foundation, creating a solid wall that will contain the heat from the firebox.
Firebox Opening: Design the opening for your firebox by leaving a space within the firewall. The opening should be large enough to accommodate the desired fire and heat distribution.
Firebox Construction: Construct the firebox using heat-resistant firebricks or refractory mortar. This will withstand the intense heat generated by the fire.
Chimney: If desired, a chimney can be built using cinder blocks or metal flue piping, extending from the top of the firebox to vent smoke and gases.

Finishing Touches

Once the core structure is complete, it's time to add the finishing touches to your cinder block fireplace:

Mortar Joints: After the mortar sets, ensure the joints between the blocks are smooth and even. Use a trowel to create decorative curves or straight lines.
Fireplace Hearth: Create a hearth with a level and sturdy surface in front of the firebox. Stone pavers, concrete slabs, or brick can be used for this purpose.
Exterior Finish: Cinder blocks can be left exposed for a rustic look, or they can be painted, stained, or clad with stone veneer to enhance the aesthetics.

Safety Considerations

Safety is paramount when constructing and using an outdoor fireplace. Keep the following precautions in mind:

Fireproof Materials: Only use fireproof materials for the firebox and hearth, such as firebricks or concrete.
Chimney Clearance: If installing a chimney, ensure it extends at least 10 feet above the roofline and is properly vented to prevent smoke buildup.
Clearance Distances: Maintain adequate clearance between the fireplace and any combustible materials, such as vegetation, fences, or buildings.
Fire Extinguisher: Always have a fire extinguisher readily available in case of a fire.