Outdoor fireplaces are both very practical additions to most yards as well as great ways to add character and a personal touch to your property. Knowing how to build an outdoor fireplace with cinder blocks for wood burning or how to build an outdoor gas fireplace does require a fair bit of know-how, however, which is exactly what we’ll try to provide you within this article.
So, without further ado, here’s our step by step guide:
Planning and preparing are always the first steps of any well-done task and DIY outdoor fireplaces are no exception.
- Ambiance or functionality? A fireplace can do both but there are usually differences with how you’d want to go about it. Fire pits, for example, are great for outdoor evening parties as are open outdoor hearths. On the other hand, a nice brick barbeque fireplace can be very practical and it can work with more than just firewood but with gas or electricity as well.
- Decide on the materials. Most homeowners try to match the material and design of the fireplace with that of their house. That’s not really mandatory, however, it’s all a matter of personal taste. Generally, brick is the traditional choice, stacked stones offer a more contemporary look, and stucco is another modern and popular option.
- Choose the right size for your needs. Consider the surroundings of your fireplace as well as your needs. Consult with your local government for the outdoor fires restrictions that may or may not apply in your area.
- Wood-burning or gas? A DIY outdoor gas fireplace or a DIY outdoor propane fireplace can be good alternatives to the more traditional wood-burning fireplaces. The later often require permits but even with a gas fireplace, you’ll do well to contact your municipal government regarding chimney specifications, setback restrictions, etc. If you’re going for a gas fireplace, you’d want to hire a contractor for the installation between the gas line and the fireplace.
- Settle on structural design for your fireplace. If you want to go the easy route you can simply buy a pre-made outdoor fireplace kit. These range from simple fire pits to intricate ornate pieces. Plus, there are many budget-friendly choices as well as more complicated and expensive options. Or, you can always design something yourself. A reinforced concrete base is one of the best bases an outdoor fireplace can have. As far as the firebox is concerned, you can either construct your own from brick for example or purchase a pre-made firebox instead.
- Choose the right chimney. The chimney is both a key design feature that adds a lot to the look of the fireplace and a key functional element. The chimney of a wood-burning fireplace needs to have a spark arrestor while the chimney of a gas or propane fireplace only requires vents.
Building the fireplace
The steps here may vary a bit depending on what type of fireplace your building but the basics are usually the same.
- Dig up a trench for the foundation. Check with local authorities how deep it needs to be. In some places, you’ll be required to dig it a whole foot deep (0.3m) and in other locations – just ~6 inches (15.2cm).
- Pour concrete for the foundation. Wait ~24 hours or more after you’ve mixed and poured the cement.
- Spread mortar on the foundation and start laying bricks, cinder blocks or your other material of choice on top of it. Use fire bricks and high-temperature mortar for the firebox.
- Use a brush and a jointer to remove any air bubbles from the mortar. After that, leave the mortar for ~24 hours to set properly.
- Add or build a chimney over the firebox. The chimney of a wood-burning fireplace must be at least 2 feet (60cm) higher than any adjacent structures and at least 10 feet (3m) away from them. If the chimney is going to be less than 15 feet (4.6m) high, make its cross-section 1/8th the area of the fireplace’s opening. If it’s going to be higher than 15 feet make its cross-section 1/10th of the opening instead. Also, remember to add a spark arrestor if it’s a wood-burning fireplace.
- Install the hearthstone in front of the fireplace’s opening. It must be at least 10 feet (3m) away from nearby structures, it should be about 4 inches (10cm) thick, and should extend to at least 16 inches (41cm) in front of the firebox. There are various materials you can use for the hearthstone but it’s important that you pick one that’s fireproof.
- If you’re going for a gas or propane DIY outdoor fireplace, now’s the time to connect it to the gas lines. Turn off the gas supply, use a plumber’s putty to connect the flexible lines, tighten the connection with a wrench, spread dishwasher soap on the connections to test them, and turn on the gas. If there are bubbles at any of the connections, that means gas is coming out and you need to refit the connection.
And that’s about it! If you want, you can add any type of fireproof veneer to the outside of the fireplace with some mortar and give it another 24 hours to set, or you can leave the fireplace “naked” – whatever strikes your fancy!