Affordable strawbale demonstration home in Sonora, Mexico

Affordable strawbale demonstration home in Sonora, Mexico


“The state of Sonora recognized that to their south, in the Valle del Yaqui, the area around Ciudad Obregon, they had vast reservoirs of wheat straw that could be utilized for building. With a new governor in place, there was motivation to begin experimenting once again with straw bale buildings and take advantage of what was learned from our Obregon experience. Once we got the project underway, we secured the help of our friend Emiliano Lopez, who was in charge of the Save the Children building as well as the Cuenca Los Ojos ranch building to oversee the construction of this house.
They used a lightweight steel frame to support the structure

They used a lightweight steel frame to support the structure

The location presented several design considerations. The area is subject to periodic hurricanes; two of the most severe were recent, 2007 and 2009. Oxidation and rusting of metal was another due to the proximity to the ocean. And as is always the case in Sonoran Desert, termites are a major concern. After considering a variety of structural approaches, it was finally decided to utilize a very lightweight steel structure, coated to protect against corrosion, in a manner similar to that which we have evolved for our hybrid straw bale buildings that utilize wood. Metal roof was chosen for ease along with clay plasters and a floor, the exterior plaster protected with a coat of linseed oil.

Read more at the source: The Canelo Project
Note: To see the image galleries of each project, click on the word ‘photo’ at the above websites.


Comments

CEDES Straw Bale Demonstration Home — 11 Comments

  1. There is one kind of building that will stand up to Hurricanes and that is the monolithic dome. Several years ago in Florida a hurricane came in and a home owner of a dome welcomed in several newsmen, cameramen and others involved in world news such as ABC,NBC,CBS,FOX and a couple others (I don’t remember their call signs). The next day they walked out of the dome and as far as the eye could see all of the houses in a 360 degree radius were blown down. It was the ONLY home still standing. It didn’t knock a glass over, knock down a picture or anything. The dome had a small chunk knocked out of one little spot and there was debris surrounding the dome. I do like these buildings but, they have made them so expensive all the while saying how much cheaper they are. This isn’t so. I’ve priced the tools needed to build them and that alone makes it costly. They’re good because it’s not wood but, when you have outrageous prices just to build them then you may save a few thousand but, it’s still too high. You ad in the labor cost plus materials. The idea behind it is sound but, thinking about a family wanting to buy the tools and do it themselves just doesn’t make good sense. If they were to drop those initial cost then more people would be inclined to build them. They do incorporate polyurethane in a spray form for insulation. Wouldn’t want to breathe it while it’s hot and vapory.

    • Yes, domes are incredibly strong and one of the best options for places like Florida. Like you say, it’s too bad the cost is so high. I think the inflatable forms are very expensive, and they charge a lot for labor because it’s specialized. One way around this is to build your dome with rebar and mesh (ferrocement). This is slower than using an inflatable form and more labor intensive and more difficult to achieve uniform curves. Both methods can be sped up with high pressure plaster sprayers. Of course our emphasis is on low cost and more sustainable methods. Stabilized earthbags could be used with a rainscreen added on the exterior.

  2. Earth bag building I believe would have been a better design and it could have been built in a more ethnically desired shape I believe. The steel roof would be a major concern because of the hurricanes and the rust factor. I must admit that I don’t know too much about termites but, I do know that they will eat through cement. With straw I kind of wonder if they wouldn’t see this as a good spot for making a home? Again, I don’t know much about these little buggers. Maybe there was more involved politically etc. to encourage the use of the straw. There may have been time limits etc. Myself, I think I would have tried to encourage them to consider a different building method.

    • Straw is an abundant, locally available resource that they were trying to utilize. That’s fine except this is a hurricane prone area. If there are hurricanes coming through every few years or so then I’d much rather be living in an earthbag structure. I would build round with a steel roof, reinforced concrete bond beam, roof tie downs and shutters. Always build on high ground even if that means just raising the site some with road base.

  3. I don’t know the actual statistics about metal roofing in hurricanes, but I’ll take your word for it that they blow off frequently. Then again, roofs blow off lots of buildings in hurricanes. That’s not exactly surprising given the crappy way most homes are built today.

    I submit that it is very likely that the reason a metal roof blows off in a storm is very likely because it is not strongly secured all the way down to the foundation.

    I am confident that even a metal roof can withstand hurricane force winds if that metal is very firmly attached to a very strong roof structure and the entire structure is strapped all the way down to the foundation.

    I’m not trying to say that it won’t get damaged. In fact, most every building will receive at least some damage in a very severe storm. Metal roofs no matter how firmly attached will undoubtedly absorb some punishment from impacts. That, however, is a lot different than having the roof blow off and exposing bales or other wall materials to precipitation.

    I see nothing wrong with using Straw Bales or Earthbags in a Hurricane prone area. Both seem equally viable in those conditions. Just be certain the building is built well. Build the roof strong and tied down to the foundation. Choose a building site that takes advantage of the natural terrain if at all possible to find a sheltered spot that is not exposed to as much wind. Design wrap around porch roofs such that if the wind gets underneath them, that only the porch roof might fly away, and not the entire roof structure for the entire building. Design very strong external shutters that are easily closed and strongly secured to protect windows during extreme weather events.

    And… most importantly… build on high ground. No matter what the building is made from, even if it remains standing after a hurricane, no home withstands flooding without damage. The best way to protect against storm surge is be above it so that the building never gets its feet swamped.

    The thing is, most of these concepts don’t require much in the way of additional costs. They simply require good design, attention to detail, and careful construction. Use the same principles, materials, and practices involved in quality construction of other aspects of the structure should be applied to the hurricane resistance aspects.

    I would much rather be inside a strong well built Naturally built structure than any standard code built structure during any hurricane or tornado. Standard Code approved buildings are death traps in the most extreme weather conditions.

    Hurricanes don’t kill people sheltering on land. Crappy buildings that don’t protect people do.

    • Most of the people telling me their metal roofing blows off are in developing countries. It happens to everyone in the community. After the hurricane they reinstall the roofing. This is the norm for them. That’s why I suggested the roofing hold-downs.

      I still suggest earthbag structures in hurricane prone areas. While bale walls could be sturdily built, earthbag structures are much stronger. Plus, water damage is so common in hurricane areas that bale walls aren’t worth the risk in my opinion. Driving rain will get blown through cracks around windows and doors, roof leaks, etc. and eventually the bales will get water damaged.

  4. It seems to me that the best approach is to design a building and a roof system that will withstand hurricane force winds. That means build a strong roof structure and make certain that entire structure is tied strongly all the way down to the foundation.

    That seems to be a much better approach than trying to design the rest of the building to withstand the harsh conditions once the roof blows away. Even in the best of circumstances, this would still be a major catastrophic event to any family. Not to mention the potential dangers of trying to ride out a storm in a building without a roof.

    If we ever hope to gain widespread acceptance from the general public for natural housing designs, it will be extremely important for the general public to see for themselves natural houses out performing standard construction. This applies to a large variety of conditions and factors, but I can’t think of a more eye popping way to demonstrate the viability of natural designs as to have a naturally designed structure right in the path of the eyewall of a hurricane and it is left standing while standard housing all around it is all damaged and destroyed.

    When the general public wants to run into the Natural building for shelter from extreme storms, and out of the standard crap housing, that is when building practices will be forced to change for the better.

    Natural builders need to welcome this kind of challenge and build structures that laugh in the face of hurricanes and tornados. Building strong walls and flimsy roofs just seems pointless to me.

    At least, that’s my opinion, for what it’s worth.

  5. If wind loading and termites are your major concerns, I would have thought a rounded design made of something inorganic would be the way to go. Isn’t making the building fit the location one of the fundamentals of green design?

    • Building earthbag in the round would eliminate all the steel framing, and it would be stronger and hold up better in the wind. Those are strong points in favor for earthbag and building in the round.

      But it’s also important to build what’s culturally acceptable. You can see here they’ve mimicked traditional adobe building because that’s what people want.

  6. I would have used earthbag construction in this instance. Hurricanes often blow off metal roofing. With the roof gone, the bales would get soaked and ruined in the rain. Earthbags would hold up in this situation.

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