by Gabriella Morrison
The options available with styles, building techniques, and materials used to create tiny houses are various (vive la différence!). Some tiny homes rest on solid foundations while others are on trailers. Some are modern in style and others more rustic. The list goes on and there is something out there for everyone. If you are the type of person that is looking for a super energy efficient, natural, beautiful, non-toxic and cost effective house then a straw bale tiny home may just be the solution for you. You may be thinking, “Build a tiny house out of WHAT??”
Straw bale technology is a tried and true system backed by copious amounts of scientific research and data to prove its merits. Tests have shown that straw bale walls are 3x more fire resistant than conventional construction. Think of it this way, straw bales are very dense and when within a wall system (and behind a thick layer of plaster), oxygen has nowhere to go. A stud framed wall as found in conventional constuction on the other hand creates a welcoming environment for flame spread by essentially creating oxygen rich chimneys in between each stud. Straw bale walls are thick, like really thick (21″) and are thus 3x more energy efficient than a conventional wall system. Most straw bale house owners save about 75% on their heating and cooling costs. Straw bale systems are also preferential to conventional construction in earthquakes and tornadoes. And don’t worry, rodents won’t get into your walls. They would have to gnaw through a thick layer of plaster and even if they got through that, they would need to make their way through extremely dense straw. Believe me, they would much rather move next door to a regular house with warm, soft and fuzzy pink insulation. Obtaining building permits has become easy and straw bale specific building codes now exist in many states. Straw bale construction lends itself very well to the do it yourselfer and is simple to learn (think giant Legos). Plus, straw bale construction uses a waste material that is often discarded in the field by either burning or flooding and is thus a part of a solution rather than contributing to the problem of using virgin resources for construction.
When John and Marie, a recently retired beautiful couple, decided to create a homestead, it was clear to them that they wanted to build using straw bales. We ran a 2 week workshop on their site last year and built two 200 sqft interior dimension cabins side by side that would become their home sweet home. Though they plan on building a slightly larger straw bale house at some point in the future they have been toying with the idea of just continuing to live in the two cabins because they serve their purposes so well.
They opted to build their two cabins side by side and right at the 200sqft size to fall within the no permit required provision (often found in building jurisdictions). One of their cabins serves as the kitchen and dining room. It is super functional and adorable. In joining them for dinner the other night, the four of us were very comfortable in the space and enjoyed an exquisite meal (they are BIG into growing their own food and most of the fare was freshly harvested). About 10′ away is their other straw bale cabin which serves as their bedroom and bathroom. They created a separate room for their toilet and shower and placed their sink in the main cabin area. The colors and feel in the sleeping cabin are so beautiful, warm and relaxing that we just wanted to curl up in bed and take a deep rest. A covered breezeway could be created in between the two cabins. If you live in an area with building codes though the inspector will take objection if you attach the breezeway physically to each structure if you are building yours as non permitted structures.
You could build each of these cabins if you did the work yourself for around $6,000 each depending on your location. This estimate covers everything but the interior finishes such as kitchen appliances, cabinetry, toilet, and shower. All of those finish details can be found gently used or new if you wanted.
Just about the only things you can’t do with a straw bale house is to have thin walls and to put one on a trailer (movement would pulverize the plaster in time). Other than that, it’s a fantastic way to go. If you are remotely curious about learning more, we invite you to our totally Free 16 Day E-Course that walks you through the process of building a straw bale house. To sign up you can click here. If you want to see more images of what is possible in a straw bale house, you can access our photo gallery by visiting here. And if you want to see what educational resources are out there to help you build your own straw bale house, you can click here. Since 2004 we have personally taught over 800 participants at our hands on 7 day workshops, had the Free ECourse downloaded over 30,000 times, heard from hundreds that have built their own, and sold over 10,000 step by step instructional videos outlying the whole process from start to finish. All to say that this isn’t just a bizarre building fad but is instead a sound method of creating a beautiful, healthy and environmentally responsible home to last for generations.
How well does straw bale construction work in humid environments? I live on the gulf coast and I would think mold could be an issue.
Hi Bryan. Straw bale homes can handle some humidity, but you are correct that excessive amounts would be an issue for the straw. The question is: what’s excessive amounts of moisture? There are straw bale homes in Tennessee, Georgia, Florida, Texas, Thailand, and other humid areas that are doing really well. Additional ventilation/dehumidifying (using an energy recovery ventilation system for example) is very helpful for bale homes in humid climates too.
Now, what if you could build a beautiful, 200SF tiny home for $8,000 ? Perhaps you need something bigger. No problem. What about a 570 SF home for around $30,000 ? That s less than most people s down payments on their homes. That means that most of the people who have recently lost their homes could actually have paid cash for a tiny home. I bet our foreclosure rates would be much smaller if more people had taken this route. By the way, smaller does not have to be ugly or cramped. With proper design, a tiny home can be beautiful and completely functional.
Can you tell me the regulations for putting up a tiny house in Fl…..
Hi Betty. I don’t have specific information regarding tiny houses in Florida; however, I would assume that each local jurisdiction will have a say in what is required. Sometimes it even comes down to local Home Owners Associations even if there are no governmental codes in place. Be sure to check with your local building, zoning, and planning departments as well as any other overseeing bodies.
The comment about straw bale houses being “preferential” where tornadoes happen should be a conditional comment. Straw bale houses built like the one shown on the straw bale workshop that posted photos recently most definitely would be preferential. There was plenty of cross bracing that tied everything to the foundation. It looked like the bales had threaded rods coming up through from the foundation. Finally, there was metal mesh fencing on the inside and the outside that was tied together inside to outside and then plastered over. I’m thinking this would make the structure much stronger than a stick built house. You want to keep your roof on and not let your walls blow in.
Hi Dave. The details that you saw in the recent workshop photos are indicative of how I recommend all bale homes be built. Shear bracing, welded wire mesh on both sides of the wall, tightly stacked bales, etc. all play an important role in creating a super efficient and VERY strong home. There are no threaded rods, or any rods for that matter, inside the bales. I use a bed of 20d galvanized nails on the toe ups to attach the bales to the foundation during the stacking. The mesh makes that positive connection permanent.
Some year, some year.
“Straw bale walls are thick, like really thick (21?) and are thus 3x more energy efficient than a conventional wall system.”
No. Different materials have different R-values. A typical 2×6 wall has R-21 insulation. When calculated across the entire wall to account for the R-6 studs and plates it works out to around R-16 if done well.
Straw bales have an R-value of 1.45 per inch. At 21″ this is an R-30 wall. There are less if any studs that create thermal bridges and so it can pretty well be assumed that the wall assembly is R-30. Maybe a straw bale wall is TWICE as energy efficient but by no stretch is it ever THRICE. This for a wall that is 3-4x thicker than standard construction.
http://en.wikipedia.org/wiki/R-value_%28insulation%29#Typical_per-unit-thickness_R-values_for_material
Brian
Hi Brian. You logic is sound; however, there are other aspects that come into play that are not represented in the standard R-value comparison.I have always had the same frustration with R-value ratings for straw bale walls, because the numbers don’t represent the reality of the efficiency. For example, the owners of the straw bale homes I have built over the years all report at least a 75% savings over their previous conventional homes (adjusted for different energy rates, square footage, price changes, etc.).
The main reasons straw bale walls are so energy efficient are:
1) Thick walls of straw. The thick walls slow down heat loss due to R-value as is the norm in any wall system; however, the shear thickness of the walls increases the R-value and decreases the ability for energy to move through the material.
2) No thermal bridging. As you mentioned in your comment, there is almost no thermal bridging in a bale home which accounts for a huge amount of energy loss in a conventional home.
3) Thermal mass. The walls are coated on both sides with roughly 1-1/4″ to 1-1/2″ of lime plaster. When fully cured, this is like having solid limestone on both sides of your building envelope. This provides additional stability to the conditioned climate in the house.
4) Tight, yet breathable, construction. Thermal bridging aside, conventional homes are known for having lots of energy leaks at each stud and electrical outlet. That is not something we see in straw bale homes, again due to the thickness of the walls (all penetrations are fully encapsulated in the straw). In order to combat the leaks, many new conventional homes are built to extremely “tight” standards. This may eliminate the leaks, but it traps stale air in the home leading to a lot of sicknesses. Bale homes are built to allow for a slow passing of air (not in a bad way like air leaks) that keeps the interior space clean without losing energy efficiency.
I have spoken with several people involved in the science of energy rating as related to straw bale construction about somehow noting the additional factors that play such a huge role in the efficiency. I don’t know whether those additions will be noted anywhere, but I sure wish they were. After all, if all the extra work associated with straw bale construction only got us a value of slightly less than twice that of conventional construction, I don’t think I would want to build a bale house either!
Has anyone done tests like a blower door test on a straw bale house to see how they stand up to what’s required for standards like PassiveHaus or any of the LEED standards? That would be interesting. I would expect them to do well depending upon how the windows and exterior doors were installed.
Another question; how are straw bale houses at stopping bullets? I’m not thinking war zone bullets, but rather some idiot over the next hill shooting up in the sky bullets? What goes UP must come DOWN. Yes, I’ve had that experience already . In rural areas this sort of thing happens.
Hi Dave. I really should know more about the blower door tests within straw bale homes; however, I don’t. I imagine that someone has done that testing and I, like you, imagine that as long as the window and door detailing, floor and ceiling to wall connections, wall penetration details, etc. are all good, then the houses should do really well.
In terms of bullets, I have no idea. I would imagine that concrete block walls would be better, but they are terrible in terms of environmental impact and energy efficiency. If you worry about being killed by stray bullets, I would expect that energy efficiency may be second on your list of important details!
Love it!
My father was born in a house with a breezeway like you described. Here in Texas, where summers get a little warm (well over a hundred for weeks at a time), it was a common building style, known as a house with a dogtrot.