How to Build a DIY Outdoor Fireplace in Your Backyard

An outdoor fireplace is a permanent, freestanding outdoor structure designed to safely house an outdoor fire and shelter it from the elements. Many homeowners use outdoor fireplaces to keep warm during outdoor activities in chilly months and as a centerpiece to increase the aesthetic appeal and ambiance of their backyard landscaping. While you can hire a professional to install this type of fireplace, you can also make one using an outdoor fireplace kit or assemble it from the ground up as part of a home improvement project.

Outdoor fireplaces are similar to outdoor firepits and outdoor pizza ovens. DIY fire pits are much simpler in construction, usually consisting of a simple, round structure that is often uncovered. Pizza ovens include an eye-level opening made of firebrick to use the heat of the fire for cooking pizzas, usually as part of an outdoor kitchen or outdoor living room.

Before you draw up plans for your do-it-yourself outdoor fireplace, here are the main structural components you should consider:

1. 1. Foundation: Outdoor fireplaces are large structures that need a strong, level foundation to remain stable. A concrete foundation is a simple DIY method that can offer good support without requiring technical skills or tools.
2. 2. Firebox: The firebox is the fireproof, innermost chamber of a fireplace, connected to the chimney flue (the duct inside the chimney through which gas or smoke passes) and the hearth (the floor of the fireplace). The firebox may be built directly on the foundation or raised off the ground, typically around knee-level.
3. 3. Chimney and related parts: The chimney is the long airway on top of the firebox that creates an airflow that feeds the fire while allowing smoke and toxins to escape. A chimney cap on top of the chimney protects it from weather damage. Some designs incorporate a flue, or inner chimney lining, to protect the material from soot buildup or excessive heat, though this isn’t usually necessary in DIY designs. Complex designs may incorporate a damper at the chimney base, which you can open and close to prevent cold air from entering the house through the flue when the fireplace is not in use.
4. 4. Screens or doors: Another common component of a fireplace is a fireproof screen in front of the firebox, which helps prevent sparks and soot from escaping the firebox.
5. 5. Decorative elements: A DIY outdoor fireplace can be as simple or as ornate as you make it. Options for decoration or complexity include a stone bench for seating in front of the firebox, a decorative brick or wood mantle for aesthetic appeal, or side structures to house wood or tools.

Here are the basic tools you’ll need to build an outdoor wood-burning fireplace as a DIY project:

• Accents: Most outdoor fireplace designs include a few stone or metal accents to increase the functionality or aesthetic quality of the fireplace. A chimney cap (metal or stone) keeps rain and snow out of the chimney and firebox, while screens or holes in the stone atop the chimney allow smoke to escape even when the cap is on. A metal screen or door in front of the firebox can prevent sparks or wood from escaping the box.
• Fireproof material: When selecting the material to make your fireplace, opt for a sturdy and fireproof option that can withstand wind and rain, like stone, brick, tile, cinderblock, stucco, pavers, and concrete.
• Foundation material: Outdoor fireplaces are large structures that need a strong, level foundation to remain stable. A concrete foundation is a simple DIY method that can offer good support without requiring technical skills or tools. For a concrete slab foundation, you’ll need a concrete mix, a shovel, a wood frame, a level, and, optionally, gravel for an underlayer.
• Mortar: Mortar is a spreadable paste that hardens as it dries and serves as the glue between each piece of material you use to build your fireplace. You’ll also need a trowel to spread the mortar.

Here are step-by-step instructions to build your stacked stone fireplace:

1. 1. Check local codes. Before making any decisions about a backyard fireplace, research local zoning restrictions to see if there are any rules regarding freestanding backyard structures or fires in outdoor areas.
2. 2. Draw your design. First, draw the shape of your fireplace with the necessary components, such as a foundation, firebox, and top-covered chimney that allows smoke to escape. Other accents include a stone bench, a mantle shelf, or storage areas for fuel or tools. If you’re having trouble with the basic shape, browse fireplace and chimenea (a type of frontloading outdoor fireplace) design ideas online to see what shapes you prefer. Once you have an idea, draw a more detailed outdoor fireplace plan with measurements to figure out how much material you’ll need.
3. 3. Choose the right spot. Many homeowners opt to place their fireplace in a focal-point spot centrally visible or nearby an existing seating area, outdoor patio, or pergola (open outdoor structure) so that they can enjoy it as much as possible. You can also choose to put your fireplace in a secluded area for a cozy hideaway or strategically place it to block the visibility of a utility pole or other functional object. Another option is to position your fireplace in a spot between your neighbors’ yard and your own to increase the privacy of your outdoor living space.
4. 4. Lay your foundation. Once you’ve chosen the right spot, it’s time to lay your concrete foundation. Use a shovel to dig out a rectangle that’s the approximate size of your fireplace’s base (using a level to ensure it’s even), and insert a wood frame to serve as the shaping structure. Optionally, lay a layer of gravel at the bottom of the hole, and then mix and pour the concrete according to your bag’s directions. Allow it to cure before building your firebox.
5. 5. Build the firebox. After your foundation is dry, you can begin building your firebox. Start with the first layer of stone or brick, laying it flat and in the shape of your fireplace’s base, securing each stone with a layer of mortar. Next, build up the sides and back of the firebox with additional stones. Once the sides and back are at your preferred height, set up a few temporary support stones in the open front and build the front overhang (called the lintel). Allow the firebox mortar to dry completely.
6. 6. Lay the chimney. Once your firebox is complete, continue building the structure upward by laying additional layers of stones on the firebox. Typically, these layers narrow to create a slender chimney atop the sturdy firebox.
7. 7. Install the finishing touches. Once you get to the very top of the chimney, follow your design to form your chimney cap, whether that’s incorporating metal screens and a metal vapor using a stone slab on top with evenly-spaced stones underneath to allow smoke to escape.
8. 8. Allow your fireplace to cure. Once every accent is in place, allow your structure to cure for at least 72 hours. Curing is the second part of the drying process in which the chemicals from the mortar complete their reactions and set. Once complete, your chimney is now ready to use.

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