MAIL: Compressed Earth

I was a little surprised by the omission of compressed stabilized earth blocks (CSEBs) from the discussion of high-performance wall systems in HP154. Human beings have been building with earth for millennia, but the modern popularity of CSEBs is largely attributable to Raul Ramirez, of the Inter-American Housing Center (CINVA) in Bogota, Colombia. Ramirez patented a clever, manually operated brick press in 1952.

CSEBs are very similar to adobe and rammed earth, but have several advantages, especially for the prospective owner-builder. As the name implies, CSEBs are strengthened by mechanical compression and a 10% cement, lime, or bitumen stabilizer.

The equipment necessary to produce CSEBs could be a few wheelbarrows, shovels, buckets, screening frames, and a basic CINVA press, or fully mechanized, trailer-mounted hydraulic machines capable of producing hundreds of bricks per hour. Numerous presses, across the entire spectrum of cost and complexity, are available from manufacturers in the United States and around the world.

CSEBs are already a part of the New Mexico building code. CSEBs use far less cement than ICFs, require only enough wood for construction, and have the added advantage of using widespread masonry trades, as opposed to specialized labor. There are countless variations on block design, which allow for structural reinforcement or architectural details. CSEBs range in strength from 300 psi to greater than 1,200 psi, and will not rot, burn, or provide food to insects. Depending on your local soil characteristics, CSEBs can be produced on site, reducing cost and embodied energy. Given these characteristics, I would love to see some more detailed coverage of this building technology in the future.

Josh Denney • Atlanta, Georgia