This page and its links are designed to put all STRAP members on somewhat of an even footing regarding the various component parts of strawbale houses. Those without any construction background will find the information interesting, while those conversant in construction techniques and active readers of the Internet Strawbale group will find it basic and redundant. However, as is true of all electronic communication, any group contains a wide range of knowledge, and all groups contain people who are looking for basic information. This page and its links attempt to establish a basic knowledge set about strawbale construction.
The techniques used to construct strawbale houses, combined with the intentions of minimizing total cost, and minimizing the use of materials possessing relatively high amounts of embodied energy, encourage, indeed demand close scrutiny of every component part of the structure. There is no final expert or word in this inquiry.
I am not a strawbale structure expert, but I have experience in "normal" house construction and am learning more about strawbale methods all the time. The path I have chosen here is to 1) define the component areas; and 2) offer some condensed wisdom gleaned from the many posts on these subjects by a great many people on the Strawbale House listserv group. The reader is encouraged to judge all information and conclusions found here with a critical eye, to understand that more options exist than are noted here, to recognize that the actual methods used in any particular strawbale structure will be arbitrary in many cases, and that choices may often be dictated by the local environment, building codes, or site conditions. The linked pages are very condensed in nature, offering only the most basic strawbale details, and are not intended to replace more detailed accounts of strawbale construction by the various books and periodicals currently on the market.
The components of a strawbale house that will be covered on individual pages are, from the ground up:
The information listed here is not intended to be exhaustive so much as it is an indication of the areas of questioning that potential strawbale builders will need to address. For more information, readers are encouraged to obtain a copy of the Strawbale House Book, to subscribe to strawbale periodicals such as Out On Bale, to search the WWW for other sources of strawbale information, and to enter into conversation with other SB enthusiasts.
One topic which spans all of the components listed above is the concept of embodied energy. Embodied energy is the total amount of energy which is consumed in the manufacture and transportation of a product, in this case, building materials. When one chooses methods and materials which have a low embodied energy, one minimizes the total environmental and societal cost of the structure, and moves toward choices which could be termed sustainable.
Embodied energy in steel, aluminum, and most metals. Much heat is needed to refine and produce each material . Most of these materials are very heavy, requiring much energy to transport them from production facility to use site. Aluminum is of course very light, but aluminum production requires very great amounts of heat. And production facilities are centralized, making transportation costs significant.
Concrete is high in embodied energy, though not so high as metals. Heat is required to produce Portland Cement, a constituent of concrete, but much less than metals. Concrete is is very heavy, but concrete plants are widely dispersed, so transportations costs are not usually a problem. And concrete requires water, though for house sized projects, this need is not excessive.
Rock (of various sizes) and sand requires little processing, but are heavy materials to transport. Thus their embodied energy is lower than metals and concrete. However the EE of rock and sand increases rapidly if they are transported any distance.
Wood is relatively low in embodied energy, requiring little heat to process, and being lighter than rock, its transportational costs are somewhat lower. But transportation costs rapidly increase EE, and its scarcity is increasing, as is its price. And at this point in history, there are many reasons to protect forest ecosystems, which should encourage an attitude of frugality in its use.
Straw is very low in embodied energy, though transportation beyond the locale increases the EE rapidly.
Some materials may not have high embodied energy, but may never the less be offensive due to the environmental stress their production, use, or disposal can cause. Rigid styrofoam insulation board, blown urethane foam insulation, and fiberglass insulation tend to fall in this category.
Embodied energy is an attitude about materials which recognizes that total material costs are greater than economic costs. While structures comprised entirely of materials having low embodied energy are to be preferred (if one values the future), there are applications where questionable materials may represent the best choice (at least until we invent better means).