1 Year Blog Update - Compressed Earth Block (CEB)

For over one year now, I have been researching and constructing an hydraulic press that will produce a strong, stabilized and extremely consistent soil or earth block with which to build my last house on our eleven acre tract of land. This house will be the retirement “resort” for my wife and I--our final “resting” place. It is also the final piece of the ecological puzzle we have been putting together, together, for twenty years here.

Having built compressed earth block churches, schools and homes in Kenya many years ago, I stockpiled some 300 cubic yards of clay when we dug the dam on our US property. That orange, gold and tan clay has been sitting there waiting for this moment for fifteen years. Now at last it will be pressed into our dream home—the same clay from which we humans were shaped and in-spired.

But why a house made out of compressed earth blocks (CEB) in a hot and humid region like East Texas? This technology has caught on hugely in Iraq where barracks and forts of CEB block are fire-proof, bullet proof, cool and quiet. But Iraq is a desert climate like New Mexico and Arizona with their tradition of adobe construction. Mass earth houses do well there. Will they do well in humid, wet East Texas?

The short answer is, yes; they are suitable--with the right insulation and roofing--for anywhere in the world. We once lived in the coastal city of Mombasa, Kenya, a very wet, humid climate, and the forts and colonial mansions there were all made of mass earth construction. Four hundred years after they were first built, they are still the buildings of choice as the interior climate is so stable, cool and quiet. So we have no fear that this house will be very comfortable, to say nothing of inexpensive to heat and cool.

How inexpensive you may inquire? Current research by Dr. John J. Moroney of the Southwest Texas College, Biology department in a peer-reviewed and published study shows that a minimally stabilized compressed earth block is a phase change material and it will act like our skin in heat—it will imperceptibly perspire and cool down the house quite on its own. The cooling effect is not insignificant as studies have shown in test structures in Brownsville and Del Rio that the interior of a CEB home can be as much as 30 degrees F below outside temperatures. That’s like having a SEER 30 air conditioner, which you can’t even buy in the US. So you begin with a reasonable cooling effect of say even 20 degree F before the AC even comes on. That’s a savings that will equal the cost of the walls and any AC equipment over five years of occupation.

When you consider that wild fires are now a constant danger anywhere in the south and west, then a fire-proof home will become a necessity! To build a stick-house out of “kindling” in the Southwest now is folly. We live hard by the National Forest, and thus it is only a matter of time before we go through a wildfire. With the roof built to meet Florida code of 150 mph, the house will be pretty safe during the expected increase of storm severity over the next 100 years as the planet warms and weather becomes more unstable.

So that’s the why we will build a CEB home. In the next blog we’ll look at how we have built the block press we think will do the quality of work we specified and produce the 15,000 blocks we have estimated it will take to build the walls of our home.

Owner drawing of brick by brick model.  Shows details of brick, insulation, arches and windows.

Architect rendering of south elevation

Architect floor plan

Block Uniformity

But the most important and least discussed problem with CEB production is not the technology or block press. There are hundreds of presses out there at all scales. They are advertised by weight, number of blocks ejected every minute, cost, and aesthetics—ours has tires and running lights! None address block uniformity as a concern, yet it is the single most important issue in this industry.

soil slurry bonding blocks into unified wall

Since construction is best done with a soil slurry which bonds the blocks into a mass, unified wall, each block must be exactly the same as the next or the uneven edge creates a modulus of rupture—a pressure point which will crack the block above it and then the entire wall. You could use a “fat” mud or cement mortar as in adobe or standard brick construction, but then your labor costs would exceed any savings. It has taken almost a year and thousands of dollars to reconfigure the prototype block press we adopted to finally get the uniformity we want. I know of no other block press that can achieve less than 1/8th inch error on any side while operating in automatic mode.

Soil Mixing

Having solved the block uniformity problem, we then went on to the “real” problem with earth construction, which is getting the soil right. We will take an entire blog to describe what we have had to do to determine the suitability of the soil we stockpiled. Then we will review soil stabilization as we will do it for our project and give a hint at some of the technical specifications any block must meet if it is to be used in a wall and contribute to the safety and longevity of the house. What I’m saying here is that, contrary to many a u-tube promo, one cannot just go out and dig up the yard, throw the dirt in a press and stack up those blocks for a wall! Well, you can, but you risk dying rather than living in such a structure!

We hope that block making will be under way shortly—end of September. We will post a schedule on this blog site for anyone who wishes to come to work and learn. No press and no “observers” will be admitted. We will work together with anyone who wants to learn the hard way—by doing it with us.

If you wish to do it with us, please do the following: email us at tiddlyinks87{at}gmail.com to request a spot. We will confirm your “reservation” by email on a first come, first served basis. Plan to camp out/stay on a Friday night, getting up early Saturday morning while its cool, and we will make blocks until it is too hot to continue or we hit our target production. You will have to sign a waiver of our liability for your health and safety while you are on our property.  We have done everything possible to ensure our own safety and health on the site, especially around the CEB press, but accidents do happen.

Our target production for each day is 500 blocks, each weighing 20-25 pounds. That’s handling 6 tons of compressed earth. If we could press 1 ton (2000 lbs.) of soil an hour, we would produce about 80-100 blocks. To accomplish that, the machine must kick out properly conditioned, stabilized, soil blocks at a rate of 1.5 per minute.

The machine as we have constructed and powered it can produce at least one block every 15 seconds or 4 per minute. Our goal is 6 blocks a minute or 360 an hour. However, one must correctly account for stabilizing and loading time, so 1.5 to 2 blocks a minute average for 4 hours seems like something a few people can actually do. Mixing and loading are all done by machines, so the only handling is taking the blocks as they are ejected from the machine and stacking them on a pallet where they will be shrink-wrapped and stored in the shade until they are placed in the wall later this year.

Soil conditioner with soil being added

final conditioned soil

After the block production, hopefully you’ll come back then and learn how to build a CEB wall with us. Block makers will have first priority for time to become CEB wall builders.

We’ll keep you posted here on production progress. We will confirm your “reservation” by email on a first come, first served basis for the wall building project as well. We have limited space for company. You will have to sign a waiver of our liability for your health and safety while you are on our property again.

When things heat up, we’ll stop, cool off, and have lunch before you depart Saturday afternoon. We have learned that this is a slow project that cannot be rushed if we are to get it right--plus, that gives us a chance to enjoy some fun and fellowship in the process.