How To Build An Indoor Fireplace And Chimney

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A fireplace is an indoor structure expertly built using stones, metal, and bricks. It’s designed to contain fire and radiate heat within the home without filling it up with smoke. Learning how to build an indoor fireplace and chimney will help you achieve both these things, bring down your electric bill during those frigid winter days, as well as make for some romantic dinners by the fire.

Building an indoor fireplace and chimney the right way depends on a number of factors including, but not limited to the amount of preparation work you do and if you choose to do the job yourself or hire a contractor. When it comes to building your own, you can save money, and it is easy enough to create a design that reflects your style, space, and budget.

Read on to find out more about building an indoor fireplace and chimney.

As is the case with the most extensive modifications to your home, there’s a lot of preparation that goes into building an indoor fireplace and chimney. While capable DIY enthusiasts can do this by themselves, it’s highly advisable to seek the help of a professional contractor. That being said, here are the steps you would need to follow if you were to build an indoor fireplace and chimney on your own.

Steps For Building An Indoor Fireplace And Chimney

Here are the steps you need to follow to build a fireplace and chimney:

Step 1: Gather What You Need (Tools & Materials)

Since there are so many different types and styles of fireplaces, materials can vary significantly from one to the next. Do you like a certain stone for the outside? Or more of a modern/industrial look with metals? Gas or wood burning? It’s really up to you to decide in this case, however you’ll always need the core tools and materials as the following (especially if you are building a wood burning fireplace):

• Hammer
• Saw
• Tape measure
• Leveler
• Stone and/or bricks
• Cement
• Masonry materials for firebox

Make sure to gather more than enough of the actual materials that you may need to build the fireplace and chimney — it’s always better to have a little more in case something goes wrong! It’s also best to find out from your local government whether or not you actually need a permit to build a fireplace and chimney in your home, because this could skew what is needed. The issue always arises when you start thinking about things like plumbing lines, gas pipes, etc. Once all that legal paperwork is squared away and you’ve gathered up all the necessary materials, move on to the next steps.

Step 2: Build The Foundation Or Hearth

When building the foundation, you need to keep in mind that the hearth must be strong and deep enough to support a couple of things – the chimney as well as the actual firebox. In many cases, you will find that it’s best to dig up a foundation that is about 100mm below the current floor level.

It’s also important to support that with a masonry foundation. This allows the foundation to be thick enough to bear the weight of the firebox, chimney, and hearth extension that should be at least 18 inches beyond your desired fireplace opening.

Step 3: Install The Fireplace Frame

The fireplace frame should ideally be made of metal. It will need to be installed about two inches into the fireplace (away from the mouth of the actual fireplace). The combustible wall’s rough opening should be at least four inches wider than your masonry. Finally, make sure that the header is at least three inches above the top of your fireplace opening.

Step 4: Build The Inner Hearth

This is where you need to apply extra care since it will be under intense heat and pressure throughout the fireplace’s life cycle. It’s advisable to use refractive mortar when laying the firebricks for your inner hearth. That is unless you are using a firebox or fireplace frame, in which case, you should follow the instructions in Step 3. If not, always use refractive mortar. Remember to ensure that the minimum width of the joints in the bricks are at least 1/16-inch.

Step 5: Build The Firebox

This is one of the main components of your fireplace and must be built with utmost care. Your firebox must be built using nine-inch refractory mortar. You should also lay the firebricks on edge. The best approach here is to use the frame of the glass door of your fireplace opening as a template. The firebricks should be laid to create the front edge of your covings and meet at the back of the door frame.

Step 6: Build The Backup Masonry

Your firebrick should be backed up by masonry that is 75% solid, which means that the firebox walls will be at least eight inches thick. You can do this by laying a 4x8x16 solid concrete block on the base of your hearth, which will act as a backup for your firebox.

Remember to leave a few inches of space between the backup masonry and the actual firebox outer shell. This is mostly because the firebox will expand once you light a fire in your fireplace, and that space gives it some room to do so; otherwise, it will crack.

Step 7: Chimney Throat

The section that combines the firebox and the chimney is known as the “Throat.” This is built using refractive masonry as well as fire bricks. It’s advisable to make the throat about 300mm deep. You could also purchase a ready-made metal throat from your local hardware store.

Step 8: The Chimney

It’s important to note that you can easily find ready-made chimneys in the market today. That being said, the chimney you use must be at least four inches larger than what it surrounds in every direction. You should make sure that all combustible materials are kept at least two inches from the outside of your chimney at any given time.

Your chimney top must be at least 2 feet higher than any given part of the roof, and it should be within 10 feet as well as three feet higher than the highest roof penetration point. Finally, make sure that your chimney opening is closed with a metal cap. This ensures that no rainwater gets into the chimney.

Remember, building codes will vary by location. That’s why it’s a good idea to hire a professional contractor to do this or at least guide you while you do it yourself.

Frequently Asked Questions

How much does it cost to build an indoor fireplace?

The costs associated with building an indoor fireplace depend on the type of fireplace you choose. For example, the installation of an electric fireplace can be between $100 and $2,200. A wood burning fireplace can cost between $1900 and $3,300, and a gas fireplace can cost between $2,300 and $4,000. Finally, a masonry fireplace installation can run between $3,500 and $5,600.

Can you put a wood burning fireplace on an interior wall?

With the help of power venting technology, it is now possible to place a wood burning fireplace on an internal wall in a room. This means you are not limited by the placement of your wood burning fireplace.

Can you have a wood burning fireplace without a chimney?

No, it is critical that you have a chimney or some other kind of ventilation system in place to remove smoke and dangerous gases.