Step-by-Step Guide to Building an Outdoor Fireplace or Fire Pit
How to Build an Outdoor Fireplace
Before you begin to research how to build an outdoor fireplace, be sure to check with your city and county to get a list of the different ordinances and codes that may apply and permits and licenses you may need. Some cities have regulations regarding the type of fireplace you can have and what fuel can be used, so check with your building inspector. Also be sure to check with your homeowner's insurance to see if it will require changes to your policy. If you know what to expect ahead of time, then you will not get broadsided halfway through your building project by an inspector putting a hold on the work.
Once you have that worked out, it is important to consider your home design as well as the design of your garden, patio, and other landscaping and hardscaping features. Keep the style and materials of the fireplace similar in look to the rest of the patio area. This does not mean that you can' t make it stand out, just design with an eye toward fitting it in to the rest of your outdoor plan.
If you are unsure whether you want an outdoor fireplace or a fire pit, you might want to read The Difference between Patio Fire Pits and Outdoor Fireplaces.
Choose a Location Carefully
As you look around your property for an ideal spot to build, you will want to consider carefully the characteristics of the location you choose.
Your location should:
- Be a safe distance from your house
- Be a safe distance from any other buildings, barns, garages, sheds, playhouses, etc.
- Clear of trees and overhanging vines and branches
- On level ground
- Not have any underground wires, cable, or pipes (call your utilities company to ask about underground pipes and cables on your property).
If you are building on an existing deck, consider whether or not your deck can support the weight of the fireplace. A wood deck could also present a fire hazard, so you may need to cover the area around the fireplace with heatproof masonry. Be sure to keep these things in mind and always double-check your plans with your local building inspector.
Outdoor Fireplace Design
The next thing to consider is how are you going to use your new outdoor fireplace? Make a list of all of the roles you want your outdoor fireplace to play and try to find a design that fills as many of those desires as possible.
If you will be using it mostly for ambiance and don't need the heating aspect, then you can go with a traditional-looking enclosed fireplace with a chimney and firebox. If you are interested in the warmth as well as the ambiance, then an open pit fireplace may be just what you are looking for. Are you going to want to use your fireplace for outdoor cooking? If so, you may need to consider what size grate you will need.
Keep an eye on the style of your home's architecture and your decorating style when you are choosing the look of your new, outdoor fireplace.
Always maintain at least a three-foot space between your seating area and the fire, no matter what design you use.
Building an Outdoor Fireplace, Step-by-Step
No matter which type of outdoor fireplace you plan on building, you will first need to prepare your building site. Remove any plants, vines, trees, or other landscaping features such as wooden fences, trellises, and the like. You don't want any fire hazards, and you don't want anything to be in the way of the various structures you may need to build.
Two Options: Fire Pits or Fireboxes
Below, you'll find instructions for both: Fire pits, then fireboxes.
A fire pit is very much like a campfire in your backyard. It can be as simple as you like, or you can build seating around it. It is the easiest type of fireplace to build for the do-it-yourself-er.
You will begin by deciding what diameter you want your fire pit to be. Once you have decided on the size, drive a stake into the ground in the center of where you want the pit. Attach a cord to the stake and attach a funnel with a small hole to the cord. If the cord is two feet long, this will give you a four-foot fire pit. Fill the funnel with flour and scribe a circle around the stake, keeping the cord taut. Repeat the process with a cord that is 12 inches longer: This will give you the area where you will build the walls, which are normally about 12 inches thick.
Remove the grass inside the small circle and dig a one-foot deep hole with straight sides. Pour in pea gravel to a depth of four inches. This will help with drainage. Add three inches of sand on the top of the pea gravel (to help contain the fire by protecting roots that may be underneath the fire pit).
Dig a four-inch deep trench with straight sides in the area between the two circles. Now, building the wall can be accomplished in several ways.
For a Dry Stack Wall
Laying down a layer of cushioning sand to level the area is a good idea, whether you are laying loose pavers or making a masonry wall. You can dry-stack concrete pavers easily to make the wall. Be sure not to use any adhesives because they could give off toxic fumes when heated.
For a Masonry Wall
For a more permanent structure, you can make a rock wall. You will need the following materials:
- Mixing tool
- Iron rake
- 1/2 inch jointer
- Chipping hammer
- Safety glasses
- Wheelbarrow to mix concrete in
- Wall stone or heat-resistant brick
- You need stones for the sides of the fire pit as well as "capstones" which are flat to make up the top of the fire pit.
- Gravel mix concrete
- 1/4-inch rebar cut into 2-foot pieces
- Pre-mixed mortar mix
- Fire bricks
- Landscaping mesh and crushed stone or gravel or bricks and additional mortar
You will build your fire pit with an inside layer of fire brick to provide a flame retardant wall, and then surround this with face stones or brick for decorative purposes. After the walls are built, the flat capstones will be used to make the top look finished and even. The wall should be no more than 18 inches high.
Take all of your measurements when you go to buy your supplies because the sales people at the home improvement store or quarry will be able to help you figure the amount of stone you will need.
Mix your premix concrete with water in the wheelbarrow, according to instructions on the concrete, until it is a soft, spreadable consistency. Spread it where the base of your wall is going to be, in the area between the two circles. Spread the concrete and tamp it down with the rake until it is within an inch or so of ground level. Smooth it carefully with a trowel.
Place the rebar in the wet concrete and tap them in until they are completely covered with concrete. Allow the concrete to set completely.
In the wheelbarrow, mix the premix mortar, one bag at a time. You do not want it to dry out as you set your stones. Spread the mortar on the outer portion of the concrete base and begin setting the stones. Set the face stones first, on the outer edge, and then come back in and set the fire brick. Continue in this way on each course, setting the facing materials first, and then setting the firebrick.
If you have never done masonry work before, you will need to refer to a guide to setting bricks. After you have set the final course, top it with the flat capstones.
For a Traditional Firebox
A traditional outdoor firebox fireplace looks very much like an indoor fireplace. It may have a mantle, hearth, chimney, and other elements of a fireplace, except it is outside.
Build a Platform
The first thing you need to do is to build a platform with concrete. Make a wooden form the same size as the base of the fireplace that you are planning on building. Prepare the base area with cushioning sand (as in the directions for the fire pit above), and then pour the concrete until the platform is the same level as the deck. Allow it to set according to the directions on the concrete mix.
Once the concrete has set, go back in and frame in the fireplace area and chimney. Double check to see that you have followed any height requirements that the city has specified. Use 2x4s to outline the shape of the chimney and the fireplace and cover carefully with plywood. Add the firebox and flue according the manufacturer's instructions.
Complete your fireplace according to your plan by covering it with stucco, a masonry veneer, or your material of choice. While there are many metal fireplaces by various companies, masonry should be the first choice for its durability and easy installation. Metal tends to rust and weaken after a few years exposed to the weather.
Make sure that there is at least one inch of non-combustible material between flammable materials and the fire.
Building with Brick
If the fireplace is to be brick, then no framing is needed. Use firebrick, a heatproof brick, and refractory mortar. Both of these materials are made to withstand the heat from a fire. Regular brick can explode when exposed to high heat, and while regular mortar will work with firebrick, it is not made to withstand the heat and is, therefore, less durable than the refractory mortar.
Using a template with a 90-degree angle, lay the first course of brick along it on the surface of the platform. Keep the brick squared up and work carefully. Build up the sides, stopping often to check the walls with a level.
There are many companies that carry outdoor fireplace boxes and flu inserts. Some companies have the whole fireplace available in kit form, which makes it much simpler to build since your materials are already there. A little research, a bit of note-taking, and a weekend or two could give you the outdoor room of your dreams. Once the fireplace is in, then you will be able to design the area around it, bringing in furniture and other items to make it truly an extension of your home.
Knowing how to build an outdoor fireplace is a great skill, and building one is a great way to improve the value of your home and increase its living space.