How to Build an Outdoor Fireplace - Outdoor Cabinets

Building an outdoor fireplace can add warmth and ambiance to your patio, backyard or garden. With some planning and effort, you can create a beautiful and functional focal point for outdoor entertaining.

Introduction

An outdoor fireplace brings the comforts of an indoor hearth outside. Sitting around a cozy firepit on a cool evening provides a charming setting for relaxation or socializing.

Constructing an outdoor fireplace requires time, skill and hard work. But it is a very rewarding do-it-yourself project that will increase your home’s value. With proper materials and techniques, you can build a safe, durable and attractive outdoor fireplace.

This comprehensive guide will walk you through the entire process of planning, designing and building a stone, brick or concrete outdoor fireplace step-by-step. We’ll cover ideal locations, safety considerations, materials, tools, construction methods and finishing touches. Follow along to gain the knowledge and confidence to complete your own successful backyard fireplace project.

Planning Your Outdoor Fireplace

Careful planning is crucial for building a functional and visually pleasing outdoor fireplace. First, determine the optimal placement, size and design before gathering supplies and breaking ground.

Pick the Perfect Location

Choosing the right spot is one of the most important aspects of an outdoor fireplace project. Safety and convenience should be your top priorities.

Select a location at least 10 feet away from your home, trees or wooden structures. This safe distance reduces the risk of fires spreading.
Avoid areas under tree branches or power lines. Fires and sparks can reach up to 15 feet high.
Pick a spot that is downwind from your house. This prevents smoke from blowing indoors.
Ensure good ventilation so smoke and fumes don’t accumulate.
Choose a visible, high-traffic area for safety and enjoyment. Situate it where you can see the fire from inside your home.
Consider proximity to seating, pathways, lighting and utilities like gas and water lines.
Check local building codes for any restrictions or permits required. Many municipalities prohibit fires in front yards.

Picking the optimal placement from the start prevents headaches down the road. Identify a safe, convenient area that enhances your outdoor living space.

Determine the Size

The dimensions of your outdoor fireplace depend on a few factors:

How much space is available in your yard?
What is an appropriately scaled size for your property?
How large of a fire do you want to contain?
How many people do you plan to gather around it?

Larger fireplaces allow bigger fires for heating and ambient lighting. But they require more materials and construction work. Here are some typical size ranges:

Small: 3 feet wide by 2 feet deep
Medium: 4 – 5 feet wide by 3 feet deep
Large: 6+ feet wide by 3 – 4 feet deep

Custom fireplaces may be bigger to make a bold statement. Scale your outdoor fireplace appropriately for your needs and property.

Select a Design

Outdoor fireplaces come in many shapes, styles and configurations. Consider these common design factors:

Open or Closed

Open fireplaces have an unobstructed pit to contain a roaring fire. This style is popular for larger backyard gatherings.
Closed fireplaces feature a glass door or metal screen. These provide more heat control and keep sparks contained.

Permanent or Portable

Permanent fireplaces are constructed from heavy materials like bricks or stone. These withstand the elements year-round.
Portable fireplaces allow you to reposition them as needed. Look for durable metal basins on wheels.

Fuel Source

Wood-burning fireplaces provide rustic, smoky fires. You’ll need a stash of dry firewood.
Gas-burning fireplaces connect to your home’s gas line or use a propane tank. These ignite with the switch of a button.
Multi-fuel fireplaces accept both wood logs and gas for flexibility.

Shape

Round or square shapes contain fires equally well. Round has a more organic, natural look.
Rectangular pits maximize the viewing area from multiple angles.
Custom shapes like stars or triangles add personalized flair.

Determine the style you prefer based on aesthetics, intended use and budget. Visit home improvement stores to view different outdoor fireplace options in person.

Create a Budget

Constructing an outdoor fireplace costs $3,000 to $6,000 on average. Prices vary based on the size, materials and design details. Here are typical ranges:

Prefabricated fire pits: $300 – $1,500
Stone construction: $2,500 – $5,000
Brick construction: $1,500 – $4,500
Concrete construction: $800 – $2,500
Gas-burning fireplaces: $2,000 – $4,000

Draft up a budget for all supplies like concrete, bricks, stone veneer, mortar and tools. Don’t forget optional items like fire screens, spark arrestors, grates, firewood storage and decorative trim. Account for 10-20% more to cover incidentals.

Setting realistic expectations for project costs prevents financial surprises down the road. Get multiple vendor quotes to find the best prices on materials.

Design & Permitting

With basic parameters determined, it’s time for formal design work. Sketch plans viewable from multiple angles. Then acquire any required permits before starting construction.

Draw Plans & Sections

Clear drawings are essential references during the building process. Sketch ideas to scale including:

Plan view (top): Outline the fireplace’s length, width, shape and exact location. Include distances to structures. Note locations of utilities and grading.
Section view (side): Draw the fireplace’s base, hearth, smoke chamber, chimney, damper and other interior components from the side.
Multiple elevations (front): Sketch the fireplace from different angles to visualize the finished look.

Refer to design books and online resources for inspiration. An architect can create detailed plans for a custom fireplace.

Acquire Permits

Most municipalities require permits to construct outdoor fireplaces, particularly permanent masonry ones. Building permits may cover the:

Fireplace foundation
Masonry structure
Chimney/flue
Gas or electricity connections

Contact your city or county building department to learn about permit requirements in your area. Apply for the proper permits as early as possible. Pay any zoning permit fees.

Permits ensure your fireplace meets all safety codes. The city will send an inspector at intervals to check compliance. Don’t skip permits—unapproved fireplaces may need to be demolished.

Preparing the Site

With blueprints and permits ready, it’s time to start site preparation. Safety should be top-of-mind during each step of construction.

Clear and Level the Area

Select an area about 1.5 times the planned width and depth of your fireplace. Remove any grass, plants or debris:

Rent a sod cutter or rototiller to strip grass down to bare soil.
Level any humps or holes using a rake, shovel and leveling bar.
Compact the soil with a tamper, roller or hand tamp.

The fireplace requires a flat, smooth and stable base. Any bumps or uneven spots become visible in the finished structure.

Construct the Foundation

The foundation supports the fireplace structure and evenly distributes its heavy weight:

Dig a pit 12-18 inches deep—deeper in cold climates.
Fill with a 6 inch gravel base for drainage.
Compact gravel firmly and check for level.
Pour a 4-6 inch concrete slab over the gravel.
Let the concrete fully cure for 1-2 weeks before building.

This essential foundation step prevents settling cracks and water damage.

Install Gas and Water Lines

If building a gas-burning fireplace, run gas lines before construction:

Hire a professional plumber or contractor to install gas lines per code.
Position lines to enter the base from underneath the fireplace.
Install a manual shutoff valve accessible from outside the fireplace.
Perform thorough leak checks before proceeding.

A water line is useful for filling buckets or extinguishing fires. Coordinate underground line placement with other utilities.

Choosing Materials

Quality materials directly impact the safety, longevity and appearance of outdoor fireplaces. Select each structural component carefully.

Fireproof Construction Materials

The interior firebox carries intense heat and requires specialized materials:

Firebrick: Dense bricks made of refractory clay that withstand very high temperatures.
Castable refractory: A concrete-like material poured and cured onsite into fireproof shapes. Withstands over 3,000°F.
Steel: Used for grates, doors and other firebox components. Choose high-temperature paint if coating.

These certified fireproof materials contain and insulate the burning firewood or gas flames.

Outer Masonry Materials

The exterior structure lends aesthetic appeal and weather resistance:

Manufactured stone veneer: Faux rocks made of concrete molded and colored to mimic real stone. Most affordable option.
Cultured stone: Made of Portland cement for added durability over standard concrete.
Real stone or bricks: Natural quarried stone and clay bricks offer authenticity. Significant cost and weight.
Cast concrete: Poured concrete shaped into rock or brick patterns. Durable but heavy.

Select outer materials that match your home’s architecture and blend with the landscape.

Mortar

Mortar bonds masonry blocks together into a cohesive structure:

Type N Mortar: Fireclay cement blend suitable for firebox temperatures up to 2,000°F
Type S Mortar: Lime and Portland cement. Withstands high temperatures on exterior masonry.
Refractory mortar: Special high-heat mortar for firebrick installation.

Match mortar types to the correct application for optimal structural integrity.

Chimney Flue

The chimney carries smoke and embers up and away from the fire:

Prefabricated chimneys: Metal kits assembled onsite. Quick installation but prone to corrosion over time.
Triple-wall stainless steel: Resists corrosion at high temperatures. Install insulation between layers.
Masonry chimney: Brick, stone or stucco exterior with clay flue liner. Most attractive and durable option.

Proper chimney height and construction prevent deadly smoke inhalation and fires.

Tools & Equipment

Assembling the right tools makes construction much easier. Rent specialized equipment beyond standard hand tools.

Hand Tools

Have these basic hand tools on hand:

Tape measure
4′ level
Shovel
Hoe
Wheelbarrow
Trowel
Jointing tool
Brush
Gloves
Safety glasses
Ear protection

You’ll use these tools extensively during excavation, mixing, bricklaying and finishing.

Power Tools

Power tools speed up preparation and construction:

Circular saw
Miter saw
Power drill and bits
Mixing paddle drill bit
Masonry cutting blade
Hammer drill
Compressor and nails

Take safety precautions when operating all power tools. Wear eye and ear protection.

Masonry Equipment

Specialized masonry tools create professional results:

7 amp 4.5″ Angle grinder
Mason’s trowel
Grout bag
Jointer
Chisel
Mason’s hammer
Sponge
Edger
Broom

It’s worth buying or renting high-quality masonry tools you’ll reuse in the future.

Safety Gear

Don’t overlook personal safety:

Work gloves
Safety goggles
Dust mask
Ear plugs
Hard hat
Steel-toe boots

Wear heavy, protective gear to prevent injury from hot materials, heavy lifting and tools.

Constructing the Fireplace

Now for the fun part—it’s time to start building. Follow these step-by-step instructions to complete your outdoor fireplace properly from the ground up.

Build the Firebox

The inner firebox forms the pit that holds the fire. It must withstand extreme heat.

Lay a bed of sand inside the concrete foundation. Pack it down evenly.
Arrange the first row of firebricks side-by-side around the perimeter.
Apply a 1/4″ layer of refractory mortar between each brick and course.
Check level and plumb with a 4′ level frequently. Tap bricks into alignment.
Build upward in a running bond pattern, offsetting vertical seams between rows.
Install firebrick on the rear wall and floor last. Cut bricks as needed with a wet saw.
Allow mortar to fully cure for 48-72 hours before lighting a fire.

The firebox walls should be 2-3 bricks thick or 12-16 inches wide. Resist the urge to rush—precision laying results in a stronger, safer firebox.

Construct the Chimney

The chimney carries smoke, gases, sparks and heat up and away from the firebox.

For prefabricated chimneys:

Assemble chimney sections according to manufacturer instructions.
Maintain the proper clearance from combustible surfaces.
Install insulation between triple-wall chimney layers.
Seal all connections thoroughly.

For masonry chimneys:

Build the interior flue first with 4″ firebrick and refractory mortar.
Construct the outer wall around the flue, at least 4″ wider all around.
Use clay flue liner blocks with weep holes to drain moisture.
Install chimney flashing at the roof junction.
Cap the flue outlet with a rain guard spark arrestor.

The general rule is to make the chimney 3 feet higher than any roof or tree within 10 feet horizontally. This ensures good draft and smoke dissipation. Use stout safety ropes and scaffolding when building tall chimneys.

Install the Smoke Chamber

The smoke chamber provides a transition space between the firebox and chimney:

Construct walls between the firebox and base of the chimney.
Angle the smoke chamber walls inward slightly to direct smoke upwards. Allow at least 16″ x 16″ of space.
Build the walls with firebrick and refractory mortar rated for high temperatures.
Keep the smoke chamber clean of ash buildup for proper airflow.

This crucial intermediate structure improves draft and reduces the chance of smoke backflow.

Apply the Outer Masonry Facade

The attractive exterior finish dresses up your fireplace:

Build a supporting wall around the firebox, leaving at least a 1″ gap for air circulation.
Apply manufacturer stone veneer using Type S mortar. Allow mortar to ooze out.
Maintain straight level courses and check for plumb lines. Keep bond spacing consistent.
Stuff sponge pieces into large joints during construction to prevent mortar oozing. Remove once dried.
For non-veneer finishes like stucco, follow specific application techniques.
Let mortar fully cure for 72 hours before fire use. Keep the outside damp to slow drying.

Take care to keep the exterior masonry pristine and soot-free when building interior components.

Install the Hearth

The hearth protects the ground in front of the fireplace from errant sparks and embers.

Measure the fireplace opening. Extend the hearth at least 16″ beyond the front and 8″ beyond each side.
Dig a 4-6″ depression and fill with a gravel base. Pack down flat.
Lay concrete pavers, stone, bricks or other non-combustible materials over the gravel. Maintain 1/8″ – 1/4″ joints.
Some hearths are constructed from a poured concrete slab. Allow to fully cure before use.
Leave the hearth surface smooth and free of trip hazards.

The size and depth of the hearth help contain messy wood ash and prevent fires from spreading.

Add Design Details

Optional finishing touches give your fireplace personality:

Mantel: A mantel offers a perfect spot for decorating with vases, garlands and candles. Use stone, exposed aggregate concrete or weather-treated wood.
Gas burner: Add a gas line, burner and ignition system for instant ambiance with the push of a button.
Glass/metal screens: Screens contain sparks and cut down on wind. Lift out when maximum heat output is desired.
Benches: Built-in benches maximize seating around the cozy fire. Leave enough room for safe furniture placement.
Landscaping: Place attractive pavers or stones around the pit. Plant heat-tolerant plants and shrubs nearby to complement the fireplace.

Apply any finishing design flourishes after completing major structural construction.

Using Your Outdoor Fireplace

Once construction is complete, it’s finally time to break in your new outdoor fireplace! Follow these usage tips for safety and enjoyment.

Season the Fireplace

Slowly seasoning the fireplace prevents damage:

Keep initial fires very small to allow materials to cure fully.
Burn fires for 2-3 hours on first use. Slowly increase duration over several weeks.
Expect tight mortar joints to expand and contract during the seasoning process. This stabilizes the structure.
Be patient during curing—gradual seasoning ensures your fireplace ages gracefully.

Don’t build roaring fires too soon or place firebricks under extreme heat before they are ready.

Practice Fire Safety

Always practice extreme caution with outdoor fires, especially around children:

Keep a fire extingu