About Strawbale
We hope this helps answer a few questions you may have. If you have any other specific questions that go unanswered, please feel free to send us an e-mail and we'll get right back to you.
Strawbale wall systems
Can I build my own strawbale home?
This is a question which drives many homeowners to build with strawbales. Generally speaking, if you would think twice about constructing a "conventional" house yourself, you should probably think twice about building a strawbale home. A prerequisite is some construction experience and PLENTY of time. In the case of an average size home (2000sf) if you have other contractors completing framing, cement work, etc...you will be hard pressed to finish before winter weather moves in. Due to the relative unconventional nature of building with strawbales, every home is custom built and therefore requires more time to construct. In most cases, it will end up taking all spring, summer, and fall to get through the construction process and the completion of interior finishes.
Some considerations to keep in mind: specialized tools are required, a thorough understanding of the concept of a strawbale wall is important including proper preparation for plaster, then when it comes to plastering you must be prepared to move many tons of material from piles, to the mixer, to the wall, and knowing what local materials are best in what ratios for your mix. Plastering comprises a significant amount of the wall system. With strawbale structures, the materials are fairly inexpensive but the construction process is very labor intensive. Books regarding strawbale building can be very useful but beware of books that may contain out of date practices or make claims of strawbale building being simple and easy.
How much does strawbale cost?
In general, hiring a crew to construct a non-load bearing strawbale wall system with exterior Lime and interior Clay or Gypsum based plasters will comprise 10-15% of the overall cost of the home.
Why strawbales?
Using strawbales to construct wall systems is considered an appropriate technology. This means that there are certain geographical areas where straw is readily available, often as a waste product, and it has been recognized as a viable, practical, inexpensive, and renewable material that offer superlative insulation and thermal mass.
Fire, Rot, and Rodents
All of the above are possible but are easily avoidable by taking certain precautions. Straw bales are tightly compressed to provide high insulative values and are too dense to burn easily. There's the old phone book analogy; one sheet from a phone book will burn easily but packed in a book it is almost impossible to light on fire. Tests have been completed which establish that plastered strawbale walls meet ASTM fire and structural standards (check our resources page for more info).
Straw is naturally resistant to rot partly due to the silica content in straw. There are many factors that impact the degradation of straw; local climate, moisture level of bales when stacked, plasters used on the bales, etc. When constructed with a little forethought and attention to detail, strawbale walls will easily outlive a typical framed wall.
If you have bales sitting under a tarp outside waiting to be used, you have a mouse hotel. We say hotel, because as soon as you stack the bales and start putting plaster on, the guests will check out. Straw is different than hay because straw has been stripped of seed and is devoid of nutrients for animals or rodents. When a strawbale wall has been plastered completely rodents are very unlikely to chew through a couple of inches of clay and surely will not munch into lime plaster. You are more likely to have mice taking up residence in your interior framed walls.
Can a strawbale home be built during the winter?
For the most part yes, everything from pouring a foundation to framing and bale stacking can be completed during the winter months. When it comes to plaster, it can be applied in cold weather but extensive tenting and heating are required to ensure that the plaster does not freeze. This can incur additional costs but if the house must be finished or a loan is maturing, plastering can commence. It is not uncommon to apply a base coat of earth plaster on the exterior of bales to protect them for the winter while the interior can easily be heated and interior plaster completed.
What is the cost difference between a strawbale home and a conventional home?
A strawbale home and a comparable conventionally built home share similar construction costs. Every strawbale home is a custom built home and therefore, compared to a custom conventional home, will have similar finished square footage costs. Quite often a contractor is hired to build a home that has no experience with strawbale-this is another factor that may end up costing you more as you will be paying for mistakes and an inherently more time consuming project.
When considering costs, it is important to not only look at up front costs but to work in the efficiency of the home and your rate of payback over a number of years-this is where you will be seeing the overall cost decreasing.
How much more efficient are strawbale homes?
A strawbale achieves a value of R35-R55 range which, in conjunction with a properly insulated roof, well thought out details, and windows with high efficiency ratings, will result in a drastic reduction of energy and cooling loads in comparison to a conventional built structure. In addition, options such as radiant in-floor heating with solar thermal panels, and south facing glazing for passive solar gain, could render heating bills non-existent. In addition, most strawbale homes are constructed without the need for air conditioning as these homes remain cool in the summer months due to their thermal mass properties.
Will straw bale meet the commercial building code?
There are numerous examples of commercial strawbale structures in use today. When the time comes, you will most likely find that many building inspectors may take a personal interest in your project and will work with you to get required permits. Even when it comes to installing systems in a certain order (which can be a different order for a strawbale) many inspectors will be lenient to save you hassle.
What about the expected life span?
Chemically, wood and straw consist of the same materials, so when sound building practices are used, precautions are taken, and maintenance is performed, these structures will outlive your children. For example, a church in the sand hills of Nebraska is over 105 years old and very much in working order.
