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STRAW BALE WALLS' ADVANTAGES AND DISADVANTAGE

STRAW BALE WALLS' ADVANTAGES AND DISADVANTAGE


Advantages of straw bale construction
1. Straw bales are made from a waste product. Once the edible part of the grain has been harvested (such as wheat or rice), the stalks often become a disposal problem for farmers. By bailing the straw, a new life is given to the material. The farmer makes some money by selling the bales and the homebuilder gains an excellent insulation and building material.
2. Homes insulated with straw bale can have insulation values of R-30 to R-35 or more. The thicker the bale, the better the R-value.
3. Straw bale walls are at least eighteen inches thick. This adds aesthetic value to the home as thick wall are expensive to achieve with conventional construction. The thickness of the wall helps to reflect sunlight throughout the room.
4. Due to the thickness of straw bale walls, every window can have a window seat or shelf. This becomes both an aesthetic and practical design element.
5. The concept of straw bale construction is easily understood by even novice builders. With supervision by one knowledgeable straw bale trainer, first-time builders can assist in the construction process. This not only spreads the word about straw bale construction, it also means that the homebuilder can save money by using a volunteer crew to help raise the walls.
6. Straw bales have a low-embodied energy. This means that very little energy was used to manufacture the product as sunlight was the main energy source for growing plant. The only energy needed to make a straw bale is in the bailing process and the transportation to the worksite. Other insulation materials, such as fiberglass, require a substantial amount of energy to produce.
7. Straw bales are 100% biodegradable—when the time comes. Straw Bale homes can last over 100 years if properly maintained. At some point, all structures will eventually be replaced. When the time comes, the straw bales can be plowed back into the earth. Fiberglass, on the other hand, becomes a disposal problem.
8. Straw bale walls can be carved with a knife or chainsaw. Openings around windows or doors can be bullnosed to a nice radius. Bales can also be finished to a sharp angular edge. Nichos can also be carved into the bales.
9. Despite what might seem logical, properly constructed walls made from straw bales have proven to be more flame retardant than conventional wood-frame construction. This is because the bales are dense and tend to just smolder when the ignition source is removed.
10. Straw bale insulation is the most effective in climates where heating and/or cooling of the home is essential for comfort.
11. Straw bale homes can be beautiful as the natural material lends itself to multiple architectural styles.

Disadvantages of Straw Bale Construction
1. SInce it is not a conventional building material, the contractor or do-it-yourselfer will need to learn new construction techniques. Although not difficult, they are different.
2. If straw bale building codes are not part of your local codes, it may be a bit more work to get your plans approved. Contact others in your area and see if they can suggest local architects or engineers that are used to working with natural materials and see they can stamp your plans and help with the approval process.
3. Straw bale walls need to be kept dry as moisture is detrimental to not only straw, but to many building materials. Moisture entering the bales from the roof above is to be avoided at all cost. If the walls of your straw bale home are kept dry, they will last for the life of the building.
4. Areas of extreme humidity and rain my not be appropriate for straw bale construction.
5. Due to the thickness of the walls (usually around 18-20 inches), more of your overall square footage will be unusable due to it being within the wall space.
6. If straw bales are not available within a few hundred miles of your construction site, the cost of shipping them, along with the potential pollution from the transportation, must be taken into account.

  • Similar to many other building materials, straw bales can be susceptible to rot if they are not kept dry, which is one of their biggest problems. You need to ensure that moisture cannot enter the bales from the roof and in areas of high humidity or rainfall, this may not be practical. If they are exposed to water, compressed straw bales may expand as they absorb the moisture, resulting in further cracking and greater infiltration of water as a result.
  • If mold becomes an issue, it may release toxic spores into the wall cavity and surrounding air, and the internal temperatures can rise as the straw bales decompose. Rats and mice can also be a problem during construction as they like to burrow in the bales, and care should be taken to ensure they are evicted before sealing.
  • Building with straw bales can also be challenging when it comes to obtaining building permits or insurance coverage, as they are not a conventional building material or part of all local building codes. You may have to be more persistent in having your plans approved, but local architects or engineers with experience in using natural materials may be able to assist in this.
  • Because of the thickness of straw bale walls, you should also keep in mind that more of your building area is being taken up with wall space and you should design your plans accordingly.



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HOW TO BUILD A STRAW BALE WALL

HOW TO BUILD A STRAW BALE WALL Straw bales can be constructed like brick walls. The bales are stacked on a concrete foundation and a moisture-proof material (heavy plastic) is used between the concrete and the bales to prevent any moisture from entering the walls from the ground. They are held by high-strength fences or rods that attach to the “board” and are as strong as wooden frames or slabs to securely secure the bale to the foundation. If a wire is used, it will pass through a curved "multiple tube" which is placed into the foundation. Many Australian designs simply use reinforced mesh as the top plate and high-strength fence line as a bondage. The bales can be stacked on a plane or on the edges and can be engraved to fit. One technique we developed was to save the cost and resources of building a garden wall by using bales on the edge rather than on the plane. The base can be narrower and use fewer packages. The top plate is a 300 mm wide trench net purchased at
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Final Step

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