Courtney May

Thanks for the replies all! I do look forward to “building an addition to my existing fireplace to make it a more efficient masonry heater.”  I have read articles and permie posts about masonry heaters. Thanks Thomas for the link the manual for the Missouri design. And thanks Satamax for the many photos documenting your build.

Next I’ll take out the piece of metal that is in front of the fireplace and check out the chimney. I have wondered if there was enough room in the fireplace / chimney to circulate the heated gas. But maybe not. Adding structural support underneath the fireplace is something i need to tackle anyway, so I can address any additional weight requirements.

I have much to learn, especially terminology. Ernie and Erica’s book is on the way! I may first experiment with retrofitting an existing outdoor brick oven/bbq, then tackle the fireplace inside.

Thinking about my question in another way: What is the most efficient use of the mass of the existing brick fireplace and chimney? Should it be used to capture and store heat?

Or, will the brick chimney above the roof just transfer out the heat from the brick fireplace that it is connected to? The bottom of the chimney is mostly sitting on the ground, same question about heat transfer.

I’m concerned about the permitting (and insurance) challenges as well. I notice the RMH rename thread and certainly one reason could be to not scare the code folks. Perhaps for my purposes it remains a “fireplace”.

Hi Permies! This is my first post. Hope the photos work and it lands in the right spot.

I have an old house located in the maritime Pacific Northwest. The house is in bad shape in lots of ways, and was sold as a “tear down.” However, my goal is to restore it in the least expensive, most simple, and natural way possible.

The house has a fireplace and a nice brick chimney. I’m interested in converting it into a rocket mass heater. The chimney originally had one side that was on the outside of the oldest part of the house (built in 1910), but a small addition was added to the front of the house and now no sides of the chimney are outside the house, except for the part that extends above the roof.



There is a concrete basement below the oldest part of the house. It needs a ton of work, including reinforcing the wall that supports the chimney.

For weight, room layout and space constraint reasons, adding a barrel in front and a bench for mass seems problematic. How can I use the existing brick chimney as the mass instead?