An outdoor fireplace can add an extra dimension to your backyard, providing beauty, warmth, and a place to sit and relax alone or with friends. If you ask a contractor to build it for you, you may have to shell out some big bucks. But if you are experienced in do-it-yourself projects, you can learn how to build an outdoor fireplace with cinder blocks.
Before you build, there are some preliminary steps you need to go through as you would for any building project. First, find out if you need planning permission from local authorities, and make sure that your home insurance policy allows for the addition of an outside fireplace. Next, you need to select your design, materials, and location. And finally, you can get to the fun part, and start building your outdoor fireplace.
We’ll walk you through everything you need to know about how to build an outdoor fireplace with cinder blocks, including pre-planning considerations, what you’ll need to do the job well, and finally how to go about it. By the time you’re done with our article, you’ll be an expert on how to build an outdoor fireplace with cinder blocks.
Things to Consider Before Building
If you’ve always wanted a fireplace in your backyard, you’ll be glad to learn that it can be a DIY project. There’s plenty of information available online on how to build an outdoor fireplace with cinder blocks, and you can also get good advice at your local building supply store.
You can get readymade installation kits or you can build it completely from scratch. It helps to have some knowledge of construction and masonry since you will pour a foundation and mix cement and mortar for the cinder blocks.
Keep in mind that any time you’re beginning a home improvement project, your first step has to be to find out the local regulations and ensure that you will be in compliance.
Find Out the Local Laws and Regulations
Many counties have laws and regulations for building activity, and they need to be considered before you worry about how to build a fireplace with cinder blocks.
You should find out if you need a permit to build your outdoor fireplace and also if there is a fee to be paid. Many localities specify the minimum distance of an outdoor fireplace from any other structures and also the fuel that can be used (gas, wood, propane, etc.).
These rules relate to safety and may also stipulate distance from fences and property lines. The safe distance is typically 10 feet from any structures and fences. There may be limitations on chimney height and materials used to ensure the structural integrity of the fireplace.
The local codes may also define the depth and thickness of the foundation to ensure the stability of the structure. Once your fireplace is complete, the local authorities may send out someone to inspect it before it can be used.
Check on Insurance Policies and Utility Lines
There are two more things you need to check on before getting started designing your fireplace. First, you must make sure that your home insurance policy will allow for an outdoor fireplace and cover any potential damages. Next, call your local utility companies to ask about the locations of their underground lines and pipes, so you don’t inadvertently damage them when digging a trench for the foundation,
The utility company may send someone out to mark out their lines, and you can take care to avoid these when planning your fireplace. Once you’ve got all these administrative steps out of the way, it’s time to design your fireplace.
Designing Your Fireplace
Your fireplace design will partially depend on where you put it and the materials you will use. The location you pick should be a safe distance from any buildings and fences and any plants, woodpiles, and other flammable materials. It may also be a good idea to build it close enough to a water hose in case of emergencies.
There are many designs you can build, and you can see several ideas online. Your design should match the house in style and size; you don’t want a fireplace that’s so large that it dwarfs the surroundings. Besides the fireplace itself, you may want to add seating and storage for firewood and maybe prep surfaces if you plan to use your fireplace for cooking.
For the seating area, it’s a good rule of thumb to allow a space of five feet in front of the structure. This will bring the front of the seats to within two feet of the fire, which is the right distance for comfortable warmth. Any closer will be too warm and further away will be chilly.
Choosing the Materials
Cinder blocks are a popular choice, as they are less expensive and virtually indestructible. One of the simplest designs for an outdoor fireplace is a basic square constructed from cinder blocks. Cinder blocks, officially known as concrete masonry units or CMUs, are easily available, relatively lightweight, and inexpensive.
You can buy them at a hardware store or scrapyard, or even a nearby construction site. Cinder blocks are also ideal because they are tough, low-maintenance, and fireproof. Many people who build an outdoor fireplace with cinder blocks add a layer of stucco or brick for a more finished appearance.
What You’ll Need
If you choose cinder blocks to build your outdoor fireplace, you can find all the materials you need at a hardware or construction supply store. Besides the cinder blocks, you’ll need cement for the foundation and mortar to hold the cinder blocks together. You may also need to borrow or rent a plate compactor for the foundation.
For the firebox, you’ll need fire bricks, or you can get a custom designed one. For the chimney, you will need a fire-rated flue pipe. To finish, you’ll need a hearthstone. If you finish with stucco or brick, you’ll also need those materials. All materials must be fireproof, including the mortar and stucco finish.
How to Build an Outdoor Fireplace With Cinder Blocks
The first step in learning how to build an outdoor fireplace with cinder blocks is to know the different parts that you will be building. The base of the fireplace is set on a concrete foundation and bears the weight of the whole structure. The firebox goes inside the base and can be custom built or made from fire bricks. You can also buy one made of stainless steel if you don’t want to make the firebox yourself.
Depending on the type of fuel you use, the fireplace has a chimney or vents. A gas fireplace will need vents but a wood-burning fireplace needs a chimney with a spark arrestor. The hearthstone which lies in front to catch any sparks from the fireplace is the finishing touch.
If you don’t want to build a more complex and traditional fireplace, you can opt to build a simple open-pit fireplace by placing cinder blocks in a square on the ground, stacked two layers high. Add a fireproof pit bowl, a grate, and a cover, and you have a simple fire pit. But if you want a traditional fireplace, these steps will tell you exactly how to build an outdoor fireplace with cinder blocks.
1. Start With the Foundation
Begin by digging a trench according to the measurements for the foundation, and then pour concrete, using a plate compacter for greater stability. Depending on local regulations, soil, and weather, the foundation may be six inches to one foot deep. Allow the cement to dry for 24 hours before the next step.
2. Build the Base With Cinder Block and Mortar
Begin layering the cinder blocks on a layer of mortar over the foundation, using mortar between layers. Use a level to ensure that each layer is level. As you complete each layer, fill in the holes in the cinder blocks with mortar.
3. Add the Firebox
Once the base is complete, you need to build the firebox. This is where the fire burns. You can add a layer of fire bricks inside the base or buy a custom-built firebox. Use high-temperature mortar for the fire bricks. Allow the structure to dry for 24 hours.
4. Finish With Vents or Chimney
If you have a wood-burning fireplace, you will need to build a chimney. Gas-fired fireplaces will need vents instead. Follow local regulations when building the chimney. These will specify its height and distance from nearby structures. The chimney will need a smoke shelf to prevent down drafts, and a spark arrester to catch embers. You can also build the chimney with a fire-rated flue pipe.
5. Install the Hearthstone
The hearthstone is the finishing touch for the fireplace and is set in front. It should be made from fireproof materials. You can have some fun choosing the hearthstone, since it gives character to the fireplace.
While you can get a contractor to build your outdoor fireplace, you may prefer to build it yourself. For an experienced do-it-yourselfer, it can be a rewarding project that will not only save money but also add to the value of your property. Once you learn how to build an outdoor fireplace with cinder blocks, you can create a space for entertaining or relaxing.