Straw Bale Construction/Introduction
Introduction to Building with Straw Bales
While use of grass-family plant fibers has long been a part of building methods worldwide, dating far back into prehistory, actual straw-bale construction was pioneered in Nebraska in the United States, in the late 19th/early 20th century, in response the then-new availability of baling machines and the lack of significant amounts of timber or buildable sod needed to build barns and housing in the Sandhills region. Under the Homestead Act of 1862 and the Kinkaid Act of 1904, the "sod-busters" were required to develop and live on their new property for five years in order to maintain ownership; building housing was a legal requirement. The straw-bale house was first seen simply as a make-shift structure, to provide temporary lodging, until enough funds were available to pay for the shipping in of timbers, to build a "real" house. However, these homes quickly proved to be comfortable, durable, and affordable, and so became regarded as permanent housing. Over the past century they have indeed outlived many neighbouring timber-frame buildings, and a number are in continuing use today and beginning their second century.
After World War II a scattering of U.S. veterans turned to straw-bale for shelter, but modern straw-bale construction experienced a re-emergence in the late 1970s, after the 1973 energy crisis helped bring issues of real sustainability to the forefront, with first examples built primarily in the southwestern United States. Now, they are being built the world around, from northern Canada, Mongolia and post-Chernobyl Russia, to Mexico, Australia and New Zealand. Because it is based on an inexpensive and renewable so-called "agricultural waste product," with a technique relatively simple for beginners to implement, involving few synthetic chemicals and providing effective energy-conserving insulation, it continues to grow in popularity, especially with do-it-yourself-ers "owner-designer-builders" and other proponents of sustainability.
Current Perspective and Regulations
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Building with straw bales is slowly but surely gaining ever wider acceptance across America, Europe and Australasia. With some charitable groups using it in poorer countries it is also beginning to appear in South America and Eastern Europe.
Government bodies are in general less hostile than you might at first expect. In many instances government bodies actively welcome sustainable building projects and straw bale building is readily recognized as a sustainable building method. Generally there is some reluctance to accept non standard 'alternative building methods by building officials. Besides adopted straw bale building codes there are now extensive resources available based on officially executed laboratory tests, studies and reports making it much easier to win them over (see the later section entitled Technical Studies, Reports and Tests for a compilation of links to such literature).
Since the initial research done in the United States to support the adopted straw bale buildings in several counties, tests have been executed in such places as Australia, Austria, Canada, Denmark, Germany, France, Hungary and New Zealand, resulting in the adoption of either local codes or the establishment of a frame work of best practices.
Around 1996 the Standards New Zealand/Standards Australia Joint Technical Committee for Earth Building (BD-083), chaired by New Zealand architect Graeme North, decided against publishing any specific regulatory standards.
Following the conclusion of the committee, in 2001 Standards Australia published an Earth Building Handbook authored by Dr Peter Walker (University of Bath, UK) with the assistance of Stephen Dobson, David Baetge, Kevan Heathcote, Chris Howe and David Oliver.
Several researchers and government bodies in Canada, including the Canadian Mortgage and Housing Company, have been testing the abilities of straw-bale construction. They hope to develop building code to be included in the next revision of the Canadian Building Code.
Building permits can be issued for alternate building methods approved by an engineer.
Early European settlers used clay to make wattle and daub, sod or cob houses. Chimneys were made from tree fern trunks heavily plastered with clay. Māori began to use sod to build whare paruparu (dirt houses) takitaki (walls). The oldest known standing earth building in New Zealand was built in 1842, the two storey Pompallier House in Russell, Bay of Islands.
Today the popularity of straw bale construction is increasing, with a growing number of specialist businesses dedicated to the area. Straw bale constructions are required to meet the standard New Zealand building regulations.
Around 1996 Graeme North, Chair of the Standards New Zealand/Standards Australia Joint Technical Committee for Earth Building (BD-083), rejected an approach to enlarge the committee's work to write strawbale standards for Australasia despite the wide range of building methods that utilised both earth and straw. The rejection was based on several reasons:
- Earth buildings rely on the binding properties of clay. Once this is absent, then you have another material and set of “rules”;
- Strawbale was relatively recent in New Zealand and Australia and did not have a large number of local examples or performance history to draw upon;
- There was no adequate funding available to enable them to do the work.
- Some members of the committee had no experience or interest in strawbale.
Despite this outcome, a few years later the 'New Zealand Earth Building Standards' were published in late 1998/1999. Standards development was managed by Standards New Zealand and supported by the members of a voluntary Technical Committee. The publications are available from Standards New Zealand:
- NZS 4297:1998 Engineering Design of Earth Buildings (Specific Design)
- NZS 4298:1998 Incl Amendment#1 2000 Materials & Workmanship for Earth Buildings
- NZS 4299:1998 Incl Amendment#1 1999 Earth Buildings Not Requiring specific Designs
In mid-2012, access to these three standards documents cost over NZD $300 to purchase, however they are usually easy to locate in a local library via services such as WorldCat and are not particularly long documents. The Earth Building Association of New Zealand suggests that the final document (NZS 4299:1998 Incl Amendment#1 1999 Earth Buildings Not Requiring specific Designs) may be useful for earth builders seeking a way to legally avoid dealing with certain planning expenses.
Also in 1998 the Building Research Association of New Zealand published an article entitled Guidelines For Strawbale Building In New Zealand by G. North, R. Walker, B. Gilkison, N. Crocker, A. Alcorn, T. Drupsteen in its BUILD magazine. This was apparently later republished as a 'bulletin' on straw bale building best practices, most recently updated in December 2010.
One of the authors of that paper, architect Graeme North, presented a paper entitled Strawbale Building Guidelines for Wet and Humid Climates (Such as New Zealand's) at an international conference in 2002.
For further information on local regulations and conditions, consider visiting the Earth Building Association of New Zealand.
- The handbook is available online for over AUD $100, a sample is also available here.
- Canada Mortgage and Housing Corporation - Documents matching 'straw'
- Rock, limestone and clay - Clay, Te Ara - the Encyclopedia of New Zealand. Carl Walrond, 2009-03-02.]
- Unit Standard 13033 - Alternative Building, Matt Thompson. 2011-08-02.
- NZS 4297, NZS 4298 & NZS 4299 - Earth Building Set
- BRANZ Bulletin #398: Strawbale Construction, Building Research Association of New Zealand, 2000.
- BRANZ Bulletin #530: Strawbale Construction, Building Research Association of New Zealand, December 2010.