How to Build an Outdoor Fireplace- Part 1: The Foundation

What You Need to Know BEFORE You Build a Fireplace

Designing, planning, building, and enjoying a new outdoor living space is as exciting as it is rewarding. But to avoid any pitfalls, setbacks, or costly mistakes, there are a few things you need to know before the first shovel breaks the dirt. I have been designing, installing, and managing hardscape builds for years. The first thing you need to do is be educated about your project. Follow along with this article to have an actionable set of steps to follow when undertaking a backyard project, like installing a fireplace kit to almost any other softscape or hardscape project.

Barrington Kit Deluxe Estate in Cottage Buff

These articles have insights that you won’t find anywhere else. But they are based on my videos that offer insights and tips that you won’t find in these articles. Be sure to watch and reference my instructional video series. By watching my videos and reading these articles, you will be ready to build your personal outdoor fireplace to help create your dream backyard paradise. If you still have questions, be sure to contact us.

Build your fireplace in a weekend youtube video

Your kit is easy and fun to build. We walk you through every step of the process.

Jake takes you step-by-step on an in-depth dive into everything you need to know to build any one of his fireplace kits. From the first course, lining the firebox with firebrick, all the way to capping the chimney- you will learn what to expect when building this project yourself.

Check Your Local Building Codes

Check your State, Local, or HOA codes. There could be restrictions for outdoor fireplaces. Mostly, regulations pertain to meeting clearance requirements from structures and property lines. Sometimes all fires are banned. Rarely will code enforcers revert to fireplace codes for inside homes. There will be no way for any outdoor fireplace to meet them. This is due to calculations based on room volume or square footage, wall length, ceiling height, etc. Know which of these you will need to meet. Sometimes it is easier to meet the requirements for a fire pit. Categorizing your build as a fire pit may help you if you are running into roadblocks. It may harm you in places that don’t allow open flames. The fix could be as simple as a screen in front of your fireplace opening. Restrictions outside of HOAs are rare. Check with your local municipality to ensure compliance before making a purchase.

“I can’t think of a time when there was no way forward if we worked with the code official or HOA board.”

Interesting Code Experiences I Have Come Across That You May Learn From

Strange codes are rare, but they do exist. But, restrictions can often be satisfied with simple solutions. Here are a few I have encountered over the years. I have had to move a fireplace (planning stage) further from the house to comply with it being at least 24′ from the residence. Since the patio wasn’t that large, I designed a smaller secondary patio one step down from the main one. I shortened and widened the central patio. The fireplace got its seating area, but I could also meet the code restriction and stay on budget while still delivering the fireplace.

I have had to move it closer to a house to comply with it being no closer than 8′ to a property line. Meeting this requirement was a simple fix. Another time, the fireplace was confined to one spot. It had to be a distance from the owners’ house, and it couldn’t be too close to the neighbors’ house. The fireplace body met the criteria, but the chimney opening was a few inches too close to the neighboring property when meeting all the other criteria. I was able to satisfy the code by modifying the chimney. I made the chimney broader and shallower. Thus, I was able to keep the cross-sectional value of the chimney the same while moving the opening over the few extra inches needed to satisfy all the restrictions. In the end, the owners required a custom chimney cap, but they got their outdoor fireplace.

Chimney height can also be an issue. A customer needed to lower a chimney as no backyard structure could be over a certain height. The HOA didn’t want structures to be taller than the fence height. Another customer had to buy chimney extensions because the chimney had to be a minimum height above the fence for fire concerns. One couple wasn’t allowed to build a fireplace. I told them to ask their code enforcer about classifying their fireplace as a fire pit instead. The inspector was open to the idea. The couple had to build their kit without a hearth to be classified as a covered fire pit. In the end, it all worked out. You never know what valuable, silly, misinformed, reactionary, or just plain weird restrictions you may find. If they exist, ask your local enforcers for creative ways you may comply. I can’t think of a time when there was no way forward if we worked with the code official or HOA board. Though rare, It is better to find them out before you buy and build and not after you do!

Plan Your Patio Layout

Always start with a plan. You should not begin any landscape project without a well-thought-out plan. Even if your plan will take years to fulfill, create a plan. Changing any landscape or hardscape feature is costly and requires tons of time and energy. Get it right the first time. You do not want a fireplace built in the wrong spot.

Perhaps you can hire a designer. Maybe you know what you want. Start with a napkin sketch (at least) if you must. Then get some yard paint and paint out your design on your lawn. See if you will affect any water, sewer, electrical, plumbing, or irrigation lines. Are there power lines you need to consider? After those concerns are dealt with, consider how you may affect drainage around your property if you make grade changes. Are you removing trees? Where will the sun be when you plan on using your space? When you sit down to enjoy your new outdoor living area, will the sun be in your eyes? Be sure to make any adjustments to your plans.

With your design (possibly modified) painted on the ground, walk around it. Move through the space. See if traffic flows smoothly. Ensure there is enough space for people, furniture, etc. Make sure there is a safe exit as well. You can’t have people stuck on a patio in an emergency. One particular place to pay attention to is the entrance to the house. Even if this is a double door, usually, only one is used. Be sure there is enough space by the door for traffic to stand as people wait and move past each other. I recommend a sizable stoop at the top of any stairs. I also recommend the steps wrap around all three sides so traffic can come in from the sides, not just straight ahead. You can see an example of this in the Patio Idea illustration.

The Foundation for Your Fireplace Kit is the most Important Part

Choose Your Foundation Type

Like any structure, the most important parts are those you don’t see. We love to talk about color and finish, but those are not nearly important as things you may never see. The most important of these unseen heroes is your foundation. We all know that a solid foundation is the key to everything- including sports, music, and relationships. This is especially the case for outdoor fireplaces. Yet the foundation is the part most people overlook or gloss over when planning their fireplace build.

Many factors can determine your foundation. One factor could be local codes. These codes may change depending on where you decide to put your fireplace. Pre-existing structures or grade changes may determine them. You may choose based on budget or preference.

Cornerstone fireplace kits are designed to be DIY friendly. To ensure this, the easiest way to keep your build DIY friendly is to build your outdoor fireplace separate from other structures. Keep them away from roofs and pergolas. Incorporating fireplaces into structures adds cost and complexity. Therefore, making your fireplace a freestanding unit offers you the most options. The best foundation is the one with concrete piers extending below the frost line. This build style should be stable in all but the most extreme soil and property conditions. The compacted gravel base is entirely adequate in stable soils. Be sure to choose which is suitable for you. 

For ease, we have a video on installing the compacted gravel floating footer foundation. You can see how you could modify the steps to add a concrete pad to the top of the gravel. Learn to screed concrete from your form boards the same way you do rock and sand. Incorporate the specs outlined in our Foundation Specs and Plans PDF. See Below:

Foundation How-to Video

Not sure how to prepare a foundation for your DIY outdoor living project? Check out our extensive how-to video. This video goes over all the aspects of what you need to know to build a solid gravel base foundation to ensure your DIY project is a success.

Foundation Instructions

Foundation-Plans

Have questions about what type of foundation is required for one of our hardscape kits? Download our “Foundation Specs and Plans” PDF. This PDF shows everything you need to know, from building on a compacted gravel floating footer to a concrete pad with piers below the frost line.

Remember, the foundation is the most crucial part of your build. Read the Foundation Specs and Plans PDF and Watch my video to familiarize yourself with what is expected of a fireplace foundation. If you are unsure about what to do, you can always call a professional.

Build Your Outdoor Fireplace Base

Building a foundation for your outdoor fireplace or grill island is not rocket science. It is manual labor. That doesn’t mean you have to break your back. Take your time and work methodically. Don’t do more than you are capable of. When excavating, timing is critical. Your soil should be the correct moisture. Too dry, and digging can be challenging. Too wet, and you can have a heavy, sloppy mess. You can wait until mother nature presents you with the ideal conditions. Luckily, these happen in the best times to build- spring and fall. The temperatures are milder this time of year, and rains can keep the soil at proper moisture. If you need to dig during a hot, dry spell, you can trickle a garden hose around the area for a few days before digging. Let it dry to the right consistency if the soil is too wet. Trickle water is the key.

building your screed/batter boards
A concrete foundation takes the same gravel prep for the sub-base. It needs a more precise form than is used for gravel-only foundations.

Don’t excavate so deep and wide that excavation equipment is necessary. You can rent and use these. Be aware that the amount of damage excavators can do is astonishing. They can easily break your house, dig through water mains, or over-excavate if not used skillfully. To avoid these hazards yet still ease your burden, use a smaller machine. Often, a tiller will quickly break up hard or rocky soils. Not only are these machines cheap to rent and easy to run, but they are also easier to transport. You can get a tiller to backyard spaces an excavator can’t go.

With a little more work and planning, plus concrete and rebar, you can build a concrete pad like a gravel foundation. The leveling and basic construction would be similar. You must construct a more precisely sized wooden form to pour the concrete. I will post it here if I cover concrete footing in a later video.

Now that you have finished the most important part of your build, you can focus on the fun stuff: Building your outdoor fireplace kit!

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