Masonry Heater Energy Cycle

This illustration demonstrates the role of masonry heaters in providing heating and cooking capacity for homes in a long-term sustainable flow of energy and resources.

Masonry heaters are essentially a solar energy solution. Well-seasoned firewood acts as “batteries” for the solar energy captured by trees in forests through photosynthesis. When the wood is then burned cleanly and efficiently in a well-designed firebox, the energy stored in the bonds of complex organic molecules that make up wood are completely released as heat energy. Masonry heaters do a great job of capturing that heat inside their mass, rather than letting the majority escape up the chimney, and radiate it out over an extended period of time.

In ideal combustion, the only two byproducts leaving the chimney are carbon dioxide and water vapor because all of the energy tied up in more complex organic molecular bonds is released. When combustion is not complete, only partially volatilized and unburned organic compounds result which are commonly known as smoke, soot and creosote. Pollution resulting from incomplete combustion represents energy potential underutilized, either by poor stove design or most often by users burning wood that has not been completely seasoned.

Ash is the portion of the fuel which is unburnable, consisting of nutrients and micro-nutrients which can be returned to the soil. These nutrients include calcium, potassium, phosphorous and trace metals.

In order to properly consider wood as a sustainable fuel source for communities, it is important to use extremely efficient appliances such as masonry heaters to provide residential heat and to take seriously the concepts of sustainable forestry practices at a community scale.

Artwork by Jonathan Mears, a friend and collaborator of Firespeaking.

Lost Creek Masonry Heater Completed!

This masonry heater features a “white” oven, ample wood-storage options, and a heated bench. The heater is faced with Idaho Bitter Root Ledge Stone, Sage Ledge Stone and the slab details are Pennsylvania Blue Stone. It serves as a visual focal point, as furniture, and as a resilient energy source for the home!

Outline for a Resource on Masonry Heaters

Here is an outline for a project about masonry heaters. Ideally it would be a publicly available web resource which was developed dynamically. Items would become links as they were written and discussion generated would be incorporated into the text. The big question is how to fund the project. Ideally, people would be moved to donate based on the utility they got from it. Comments are open below to provide feedback on the project. Feedback will fuel its creation! Also, join our mailing list to receive updates.


  • Why Fire? Why Firewood? Why Masonry Heaters?
  • Gentle Giants of Healing Warmth
  • 2 Kinds of Efficiency – Combustion & Heat Exchange
  • The Challenges Presented by Masonry Heaters
  • “The Cathedral and the Bazaar” Approach


Masonry Heater Architectural Design

  • Heart of the Home
  • Inspirations
  • Placement
  • Clearances to Combustibles

Masonry Heater Technical Design

  • Design Methodology
    • Concept
    • Layout
    • Sections
    • “Brick-by-brick” Design
  • Comparison of Design Philosophies
    • Russian
    • Contraflow
    • Five-Run
    • Bell
    • Rocket

Masonry Heater Construction

  • Comparison of Basic Approaches
    • Pre-Fabricated / Manufactured
    • Core Kits
    • Custom
    • Hybrid Steel & Masonry
  • Foundations
  • “Double-Skinned” Construction : Core & Facing
  • Chimneys
  • Masonry Heaters & Construction Codes
  • Budget

Resources & Next Steps

  • Workshops
  • Organizations

Plans for a Masonry Heater Core

The world needs more masonry heaters and masonry heater builders! A shortage of viable plans as well as education opportunities means there are very few masonry heater builders in North America. This design work reflects an effort to simplify things in order to make the process easier for everybody involved.

New approach to masonry heater building!

For the masonry heater we are currently working on, we took a new approach to the design and construction of the core by casting the most complex parts. The goal of this is to simplify both the design and construction process so that we can streamline the process for our own projects as well as produce a viable strategy and parts for other masonry heater builders.