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Other Contemporary Straw-Bale Homes: Although the straw-bale method has a long history, official recognition of straw-bale construction is just beginning. In the last decade, modern straw-bale construction pioneers have braved reluctant contractors and hesitant local building officials. The result has been a slow, but continuous, growth in construction of straw-bale houses. Straw-bale dwellings range from small owner-built units to large, contractor-built luxury homes. Costs vary from $5 to more than $100 a square-foot depending on a number of variables, as discussed in the next section. Photos on the opposite page depict the variety of styles of contemporary straw-bale buildings.

Affordability: How Affordable is a Straw-Bale House? A straw-bale house may cost the same as a conventional wood frame house. However, there are many factors that can make a straw-bale house less expensive; and, there are additional benefits to building with straw. According to a 1982 Housing magazine cost guide, exterior and interior wall systems comprise approximately 30 percent of the cost of construction for a typical wood frame, slab on grade house in Albuquerque, New Mexico. With the recent increases in the costs of materials, particularly lumber, this cost is presently estimated to be considerably higher. For example, lumber prices rose 70 percent during the last six months of 1993. This hefty increase added approximately $4,000 to the cost of a typical 2,000 square-foot house.

A 2,000 square-foot straw-bale house requires about 300 standard, three-wire bales at a cost of approximately $1,000. The cost of a "Nebraska-style" (structural) bale wall is about one-fourth that of a comparable super insulated wall. Of course, there are many other variables that go into building a house such as the cost of labor, choice of finishes such as siding, roofing, flooring, and other amenities. Unique to straw-bale construction is the broad range of costs associated with different levels of quality available to builders.

  • How To Buy A Straw Bale: Straw-bale construction consultant Judy Knox from Out on Bale (un)Ltd. raises the following considerations about selecting bales:

  • Purchase bales following the harvest when they are usually inexpensive and abundant. Make sure the bales are stored high and dry.

  • Obtain the bales from feed stores and other retail outlets, wholesale brokers, or directly from the farmer. Retail outlets are the easiest and most expensive sources. Wholesale brokers offer direct access to the bale supplier and often offer commercial transportation. Dealing directly with farmers may give you more say about bale quality and consistency, but you will likely have to address bale transportation.

  • Don't rely on hearsay concerning the size and condition of any bales you might buy. Check out the bales yourself.

  • Bales must be tightly tied with durable material preferably polypropylene string or baling wire. Avoid bales tied with traditional natural fiber baling twine. When you lift the bale, it should not twist or sag.

  • Make sure the bales are uniformly well-compacted.

  • Look for thick, long-stemmed straw that is mostly free of seed heads. Wheat, oats, rye, barley, rice, or flax are all good.

  • Test most bales to make sure they have always been dry. Bale moisture content should be 14 percent or less.

  • An ideal bale size proportion is twice as long as it is wide. This simplifies maintaining a running bond in courses.

  • Try to get bales of equal size and length. If they do vary in length (as many will), lay ten bales end-to-end. Measure this entire length. Then, divide by ten. This is the average bale length to use for planning.

  • Frequently Asked Questions About Straw-Bale: This section answers some of the most commonly asked questions about straw-bale construction:

  • Will the bales rot? Without adequate safeguards, rot can occur. The most important safeguard is to buy dry bales. Fungi and mites can live in wet straw, so it's best to buy the straw when it's dry and keep it dry until it is safely sealed into the walls. Paint for interior and exterior wall surfaces should be permeable to water vapor so that moisture doesn't get trapped inside the wall. Construction design must prevent water from gathering where the first course of bales meets the foundation. Even if straw bales are plastered, the foundation upon which the bales rest should be elevated above outside ground level by at least six inches or more. This protects bales from rain water splashing off the roof.

  • Will pests destroy the walls? Straw bales provide fewer havens for pests such as insects and vermin than conventional wood framing. Once plastered, any chance of access is eliminated.

  • Are straw-bale buildings a fire hazard? The National Research Council of Canada tested plastered straw bales for fire safety and found them to perform better than conventional building materials. In fact, the plaster surface withstood temperatures of about 1,850 degrees F for two hours before any cracks developed. According to the Canada Mortgage and Housing Corporation, "The straw-bales/mortar structure wall has proven to be exceptionally resistant to fire. The straw bales hold enough air to provide good insulation value, but because they are compacted firmly, they don't hold enough air to permit combustion."

  • Are straw-bale buildings acceptable to my local building code? Most cities and counties have adopted one of three or four model building codes. City, county, and State building codes may be different. Straw bale is acceptable to some codes, and not acceptable to other codes.

 

Hints On Obtaining A Permit To Build A Straw-Bale House: If your community has adopted a building code, you will need a building permit before beginning construction. The local government's building official is the community's designated expert and enforcer. He or she has the responsibility of interpreting the codes, inspecting homes under construction, and making exceptions to the code, if requested. As a first step, identify local building officials and code requirements. Out on Bale (un)Ltd. recommends the following steps to help you obtain a straw-bale house building permit.

  • Obtain and read a copy of the current building codes for your area.

  • Gather as much information as you can about straw bale construction.

  • Talk with straw-bale experts and others interested in straw bale building.

  • Before drawing up specific house plans, meet with local building code officials. If they are not familiar with straw-bale construction, you may want to take along a knowledgeable architect or builder. Give the building officials copies of supportive information; allow them to digest the information, then meet with them again. Develop a rapport with them during the planning and building process.

  • Become familiar enough with the code and straw bale to be able to discuss and defend your design decisions as they relate to the code. If necessary, you might suggest a small straw-bale demonstration structure, perhaps a small storage shed. This will allow building officials to become familiar with the materials and construction methods.

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