The floors of our buildings here at our desert homestead are all different. Adobe and flagstone are the primary materials. One building has flagstone flooring and the other three have adobe floors. Each of the adobe applications used a different set of materials besides adobe and each has turned out to have very different color and texture from the others. We decided against concrete because we were a crew of two and a bit weak in concrete finishing skills. We had helped lay a large concrete patio base for our son and the drying time snuck up on us. The result was not what we would have liked. We knew from previous experience that adobe dries much more slowly and is more forgiving. There is also the comparative benefit of natural material, adobe, versus material with a great amount of embodied energy such as concrete for those considerate of Mother Earth. We do use cement, but try to use it sparingly.

    
In all the floors, we began with a well-tamped sub-floor of AB sand mix such as is used in a road base. With repeated leveling, wetting, and tamping, this material provided us with a solid base for our earth and rock floors. The material was inexpensive and available from our local sand and gravel people.

         
For those who don’t have a young fellow teacher ready to help out for a few hours, small power tampers are readily available from tool rental outlets. On damp evenings, my shoulders can still feel the effects of tamping down sub-floors by hand in three buildings plus the shop. We don’t have a rental outlet anywhere within 75 miles of the homestead, so it was a hand-tamper for us.

The results using hand tamping were fine, though the process took longer.  The tamped sub-floor was brought up to two inches below the ultimate finished floor level. The rest of the way would be either stone or layers of adobe.

       
The need to have precisely level floors was not as great in the Bear Cave and the shop, so we simply used wood guides for the layers above the sub-floor.

Using dimension lumber in the same manner as screed boards in concrete work, we spread and smoothed the first layer with a garden hoe and a long, handmade combination trowel and screed called a darby float.

    
In the main straw bale house, we wanted more precision and were dealing with a larger floor. Armed with an antique surveying level and rod, we put pegs in the subfloor in a grid so that each peg was reachable from two other pegs with a four-foot level. I know that there are wonderful laser levels and such that could do this job as accurately in less time, but we were watching the budget pretty carefully and the tool we used belonged to Barbara’s dad. Hard to beat a tool that works well and costs nothing.

    
For the main floor, the knee work started when the pegs were in. The floor was built up in three layers including the brushed on aliz. We put in a thick layer, about 1.5 inches, of a damp mixture of  adobe with straw and coarse sand. This was tamped down in much the same manner as the AB. After a few days to nearly dry, a wetter layer of the same material was troweled to the tops of the guide sticks to maintain level.

The final coat was put on in one day to prevent seams and cracking. We screened the adobe to a 1/8 minus clay and used very finely chopped straw. Before this coat was dry, we mixed up some 1/16 minus aliz clay and mixed in to the consistency of heavy paint. This was applied with a wallpaper paste brush and smoothed with a pool trowel. The results were very satisfactory. When the floor dried, we began putting coats of boiled linseed oil on as a sealer. More about that in another blog. The floor in our house is without cracks, level, and a pleasant brown. We will be adding another coat (the fourth) of linseed oil in a few weeks and then will use an acrylic floor wax to bring up a bit of a shine.

    
In the woodshop, I wanted to try an experiment. I read that well-composted horse manure is used around the world as a binder in earth floors. As it happens, we have a neighbor with three delightful manure factories named Bueno, Cody, and Bugsy. When we mixed the adobe in the same manner as for the house, we added one shovel of old manure for each five shovels of other material. The mixture troweled like a dream, has no cracks, and no odor. I would use it again in a heartbeat. While not for fecophobes, this is a great method for those that want a natural binder in adobe.

      
In the utility building, we decided to use flagstone. We had found a great buy on a substantial amount of flagstone and knew it would hold up with laundry, shower, and food prep spillages. I actually think a well-oiled adobe floor would do so as well, but we preferred to err on the side of strength and impermeability. There really isn’t much to say about installing flagstone. A simple, but labor intensive, job that requires a good bedding material such as a fine grit sand to accommodate the irregularities in the stone and then finishing the job a good grout and sealer. For grout, we simply used Portland cement in a ratio of 1 part cement, 2 parts sand, and 3 parts small aggregate. We used the 3/8 material left over from screening the adobe as aggregate.

Our floors are all unique in appearance. As is the case with most DIY projects with local natural materials, costs are very low and the rewards are many. While not recommended for those that like a slick, uniform appearance, the variegations in texture and color make these literally one-of-a-kind floors.

If you’re building with straw, cob, earth bags, or other earth-friendly material, you might do well to include an adobe floor.  For more on our desert homesteading experience, you're invited to visit us at www.grow-cook-eat-beans.com. Happy building!

Adobe clay is one of the most pleasant materials available for building. Adobe is forgiving. Make an error or have a problem and you can start over by wetting it down and peeling it off or retroweling. For newbies like us, this was really important.

Adobe clay is a natural material with only the embodied energy involved in transport, unless you count the energy expended by the builders. In many parts of the world, clay is abundant. For example, there are clay deposits in colors ranging from red to gray within just a few miles of the Bear Cave.  

Adobe clay is economical. Our 320-square-foot adobe cottage, the Bear Cave, has adobe block walls, adobe plaster, and adobe floors. Total cost for the clay was less than $500 in 2008.

When it was time to finish the walls on our straw bale house (above), we didn’t think twice. It had to be adobe. We used the same clay, with different screenings, for every application except the finish coat on the interior. For that, we bought some Kaolin clay mined and bagged in northern AZ and mixed it with 60 grit bagged sand. We love the outcome, a nice balance of finished wall with a flavor of rusticity.

With the straw bales up, windows and doors installed, and interior build out finished, it was time to plaster. Materials for preparing the walls included adobe clay, chopped straw, and water. The first step was to chop straw. We had a few bales left from the house walls and bought a couple more from the local feed store.

At first, we chopped using a weed whacker and a thirty gallon heavy “rubber” garbage barrel. The straw chopped with this method was fine for filling seams, but when we began work with the trowels after this preparation process, we wanted more uniform chopping and borrowed a neighbor’s mulcher.  For some finish applications on the adobe floor, we ran the straw through the mulcher twice.

Our adobe clay, fresh off the truck, had been ostensibly screened to 3/8" minus. However, we had some variety of rocks up to 3/4" or larger. We set up two screens outside, one with 1/4" hardware cloth and one with 1/8" hardware cloth. For brown coat and scratch coat trowel work, we screened with 1/4" and for finer work used the 1/8".

For filling in the seams and holes left in stacking our straw bale walls, we mixed adobe clay screened through 1/4" mesh with chopped straw. The mixture was heavy in straw and the clay was simply a binder. Straw, clay, and water were put into our old cement mixer until the right consistency was achieved. Firm enough to hold when slapping it into the seams and wet enough to bond to the bale. For major holes and seams such as around window bucks and above the doors, we would push in as much as would stay, let it dry over night, and make one or even two more filling applications. This process was the first step in getting a straight and even wall.

It must be noted that there are probably as many different ways to plaster a straw bale wall as there are plasterers. We have tried a few and this one worked well for us. There are many who will swear that there is only one method - theirs - that should be used. Probably not! This one worked for us and I have seen other, different, processes that turned out beautiful walls as well.Many right paths to a desirable result.

One of the methods often promoted is the use of poultry net or chicken wire as well as metal lath and other such materials as the base for plaster. I have to come right out and say that I hate, yes – hate, plastering with adobe over chicken wire. Granted, it grabs the mud, but often leaves air space between straw and plaster that compromises the integrity of the wall. I know that if other plasterers read this, many will strongly disagree. So it goes.

I do agree that it is important to provide a surface with “tooth” that will allow the brown coat to adhere to the straw. To that end, we did a final screening of our adobe through a kitchen colander, getting a very fine and uniform clay.

Mixing water and this fine adobe gave us an aliz or fine plaster about the consistency of heavy paint.

With a sprayer designed for joint compound purchased from our hardware store, we sprayed all the surfaces we intended to plaster. Please note, there will be over spray, so mask all the windows and doors as well as any outlets or fixtures already installed that you don’t want coated in a fine layer of adobe clay. As we wanted uniformity on our walls and out interior build out was done with frame and sheet rock, we taped the sheet rock and then sprayed it with the aliz as well.

We did not put either a brown coat or a scratch coat over the sheet rock and the finish coat of plaster adhered beautifully.

This wall is now ready for the trowel!!! 

The pictures you see here were taken while preparing the interior walls for plaster. The exterior wall preparation was identical. The finish plastering process was different and will be addressed in a later blog.

We have been through two monsoon seasons and one winter with our new home protected by adobe plaster. It is withstanding temperature swings over 100 degrees, driving rain and snow, and the fierce Arizona sun. No problems.

Plastering is at once the most labor intensive and the most satisfying activity in building a straw bale home.  If you are going to create a straw bale home with adobe plaster, I suggest reading about the process. I also suggest a practice wall. Stack and support three straw bales, attach a layer of burlap on which to apply plaster, and apply different plaster/straw mixes until you find one that works for you. After you check out one formula, just peel off the burlap, rinse it off, and start over  It would be pointless for me to try to give portions of straw to clay as all clays are different. Besides, it's fun to experiment.

For more information on this process and for other resources and books, I hope you will visit me at www.grow-cook-eat-beans.com. I would be happy to answer specific questions here or on my web site.

So, read, think, plan, experiment, and, above all, enjoy the process. It’s worth it!

Climate and weather in the high desert of Arizona are harsh. Granted, we don’t have the severe cold of northern states, but monsoonal rains driven by 50 mph winds and intense sun that will burn skin through a long sleeved shirt can be tough on a building made of straw and adobe clay.

To counter the effects of the wind, we built our house with its back to the prevailing winds from the west and put only one window in the back wall. For rain and sun, we opted for a 360 degree porch or patio. Choose the name you like. Basically it’s an extension of our roof 8’ past the outer wall and floored with flagstone. With this overhang, our adobe plaster walls were protected from all but the most severe driving rains and our windows were shaded from the intense Arizona sun. The overhang also gave us a shady spot out of the wind to enjoy our mountain views any time of day. All good things!

Our porch began once the trusses were installed on the house. We completed the sides of the porch completely before starting on the main house roof to allow access under what was to be a shallow, 12 inch overhang from house to porch as well as making work on the main roof accessible without ladders.

We had dug out and poured 12”x12” blocks of concrete with 6” post anchors to accommodate our porch posts when we poured our footings. Out here, peeled logs called vigas are often used as visible supports in roofs and ceilings. We used them as vertical porch posts for Southwest aesthetics and the price was not too bad.

With the vigas plumbed and braced, we fastened the bases firmly in place with lag screws. Eight foot 4”x6” beams spanned the distance between the tops of the vigas. To attach them to the uprights, long barn spikes were driven in at an angle through predrilled holes. We used a lap joint cut into the beams at the corners and secured them with a spike driven through the lap joint into the top of the viga.  After the beams were set, 3" garden post stock was cut into 2' lengths with opposing 45 degree cuts and used as a corner brace for the top of the viga. We liked the way it looked and felt it was another move toward stronger building.

In honor of my blacksmith grandfather who believed that it was impossible to build something that was too strong, we used steel t-straps to further strengthen the joints between beam and post.

With the outer “wall” of our porch in place, we measured and mounted angled rafter/joist hangers from the bond beam plate. Angles cut with our trusty chop saw made a good fit for the rafter ends against the bond beam. Recognizing that wood twists and warps and that sometimes we aren’t as accurate as might be, we left the outer ends of the rafters to be cut in position with a handsaw after a chalk line marked our target. This enabled us to have a straight fascia board.

After ensuring the 2”x6” rafters were true and square, we fastened them to the bond beam with hurricane straps. A little more time spent with some accurate marking and cutting a series of double miters produced our corner hips. I found that double miter cuts on an inexpensive chop saw such as we have is a bit time consuming. One of those places where someone who is not a pro carpenter learns to measure twice and cut once. Crossing your fingers doesn’t hurt either, but not while you’re cutting

Before nailing on the fascia boards, a chalk line and adjustable square gave us our cut lines and we sawed off the ends of the rafters parallel to the bond beam.  Some heavy lifting brought the OSB sheathing up on the rafters, followed by a few snaps of the old chalk line and the nail gun fastened the sub-roof to the porch. Our first shade! When the OSB was in place, cut long to allow for the depth of the fascia, we began nailing the 1”x6” fascia boards into place.

Rolling out tar paper or felt roofing paper, call it as you like, in a high wind is not my idea of a great time. As a consequence, we began our roofing early in the morning, before the daily winds and used some lathing and short sheet rock screws to keep our paper in place in the event of a stray gust. We only did the porch sides and left the corners and gable ends for after main roof was completed. We wanted to be able to build from the porch roof without damaging the finish on the roof steel, but had to put steel on before hand to accommodate the roof overhand. A matter of planning and staging.

So, leaving the ends unpapered for now, we attached our drip edge above the felt paper and made ready for the steel porch roofing. Each manufacturer and each roof rib design calls for a slightly different screwing pattern. When we received our steel, a cover piece was included to protect the finish on the purchased pieces. We set up saw horses under our newly made shade and made a template from the cover piece following the pattern recommended. Carefully predrilling holes in the template meant that we could drill a pattern of starter holes in each sheet of roofing steel on the ground.

Being able to start gasketed roofing screws in predrilled holes meant that there was consistent fastening and less bending over.  As you can see from the pictures, this is a desirable thing for me, enjoying an excess of both years and girth. The uniform screw pattern made for better roof aesthetics as well.

The ground crew, Barbara and Anneke, attached strips of mastic or roofing "bubble gum" on the appropriate edge and sent up the predrilled sheets. The side roofs were covered with steel in about an hour. We had a porch and were ready for the main house. After that, the remaining paper, drip edge, and steel was installed to complete our project.

While we have more square feet under roof on our porch than on our house, with attendant costs and work, I would not build differently.  I can wander outside to view our beautiful desert and be dry while watching the rain fall on our often parched desert or relax in the shade while sheltered from wind.  I am thankful we decided to build a wrap-around porch for our straw bale home.

From installing the window and door bucks to topping the walls with bond beams, this crew of four completed the exterior walls on this DIY 720 sq ft house in four days. Next comes the roof!

Barbara and I retired from teaching high school the last week of May, 2009. With the help of our neighbors, Dan and Anneke, we moved lock, stock, and barrel from Tucson to Cochise with a couple round trips in a pickup with horse trailer, Chevy Blazer, and Barbara’s little Corolla. After a day of resting from the move and getting organized, we were ready to build. This blog is not just a chronicle of our straw bale house walls going up, it is a “thank you” to our neighbors, Dan and Anneke. They not only got us moved, but devoted their time and energy to helping us get our walls up. They are the kind of people that put the “good” in good neighbor.

About a week before we retired, our ranch supply store delivered about 180 straw bales freshly baled and tightly packed. Bales from different machines can vary in size, number of strings, and the length of the straw strands. Our bales averaged about 4 feet long x 15 inches high x 24 inches wide.  The bales we bought had long strands, which made a variety of building chores easier than a chopped straw bale. The market here at that time was $6.50 per bale. Thus, our walls, without rebar pinning or bucks, cost us $1,170 delivered. The bucks and rebar pinning added a couple hundred dollars more.

To accommodate openings less than 4 feet, we had to retie bales into shorter lengths using baling twine and bale needles. Retying with long strand bales was a dream compared to the choppy bales our neighbors used. A long-strand bale holds its shape, while a short-strand or chopped straw bale tends to crumble when retying. Ugly!

To retie our bales, we measured our new bale length and pushed a bale needle through the bale near one of the existing strings.  We pulled a loop of new baling string up through the bale and tied off in both directions, creating two new shorter bales. Once a new string was tied next to all three original strings and the two new flakes were tight, the old string was cut and put aside for the next use.

I made the bale needles from a couple pieces of galvanized fence end strapping that were salvaged from a neighbor’s project. Our needles were about two feet long, excluding the handle. I bent the handle in my vise and used a grinder to cut a retaining notch and make a point on the needle. Cost = Zero. It is possible to purchase “professional” bale needles from a variety of resources, but why?

Wall raising day arrived. We were rested and ready to go. June is hot here in southern Arizona and our neighbors have their own ranch to tend, so our work day usually started about 6 a.m. and stopped about 1 o’clock in the afternoon. Our first day was something of a shake down. We got our tying system running well and the door and window bucks installed and the first course of bales on the stem wall. It felt good to get started. After Dan and Anneke left, we did clean up and got ready for day two.

 On the second day, the wall grew to four rows. We began pinning the wall at the fourth row. Five foot lengths of 3/8 inch rebar were cut and driven through the bales every two feet to stabilize the wall. We made sure to drive the rebar entirely into the top bale to avoid tripping or kneeling on an exposed end. With the bottom course of bales firmly pressed unto pins sticking out of the stem wall and the additional rebar pins every additional third course, we had a strong wall.  

At the corners, we impaled each corner bale on a piece of 3/8 inch all-thread three feet long. The first section was anchored in the stem wall. We joined each length of all-thread with a long nut to give us an adjustable mechanical tie from stem wall to bond beam on each corner. This helped secure and level the bond beam. We were careful not to cut any bale strings as we drove the rebar pins.

There are many methods of stabilizing straw bale walls. Interior pins, exterior pins of bamboo tied through the bales, strapping and on and on. If done well, all will do the job, I suspect. We found that exterior pinning caused cracking in the plaster on the Annex wall, so chose interior pinning for our home.

 As I am getting to be a bit “long in the tooth” and much closer to 70 than to 60, I don’t try to buck bales above four courses anymore. When I was 20, it was a different story, but – Oh Well!

As a consequence, we used Dan’s little tractor bucket and a scaffold to work the wall as it rose. I must admit that walking along a wall made of a single row of bales as it shifted and moved is no longer a source of entertainment for me. And when the job involved reaching into the bucket of the tractor with a hay hook and dragging a bale into place on the wall - well, I’m glad it’s done.

Once the bond beams and final pinning was done, the wall didn’t move at all and working the trusses in the next phase of building was a breeze.

By the end of the third day, we had the end in sight. We had originally intended to build a wall only six courses high. But when we were through with the sixth course, we discovered that the door and window spaces had left us enough material for a seventh course.

Nothing in my body wanted to do that as I was one tired puppy.  But in retrospect, I’m happy we pushed the wall up one more level. Our interior ceilings are about 9 feet now and, although our house is pretty small, the fact that the interior space is pretty open and the ceilings are high makes it feel much more spacious.

The fourth day was comparatively easy. We had few bales to cut and tie as we were above the doors and windows. We had our system down pat by now. The job was finished with lifting one last row of bales and the placement the bond beams. Each 8 foot section of bond beam was attached to the next with carriage bolts and shimmed level.

We drilled holes and drove our second round of rebar through the bond beams and down three courses of bales to further strengthen the walls. The protruding all-thread on the corners was fastened with a large wood washer and a steel 1 1/2 inch washer to lock the corners into place. The following day, we began the roof. But that’s another story!

Today, as I write this, it is 103 degrees outside. Our R-42+ walls keep our inside temperature about 68 degrees with the help of a small evaporative cooler that runs on low setting and isn’t cranked up until late afternoon. This past winter was cold for Arizona.  We had a couple days in single digits, the lowest being 2 degrees above zero. We heat with a small wall-mounted propane heater. When we went to bed on the coldest night, the interior of our house was 70 degrees. We turned the heater off at 8:30 p.m. and, when I got up at 5:00 a.m., it was 62 degrees in the house. Straw bale homes are great!