The following are some pros and cons of building a straw bale house. Like any building material, it is always best to work with your architect to evaluate your needs and your goals before committing to a particular material.
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Advantages of straw bale construction
- 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.
- Very good insulation. Keeps heat away when it is hot and keeps warmth inside when it is cold.
- 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.
- 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.
- 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.
- 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. Stones/masonry, EPS panels and other building technologies on the other hand, become a disposal problem.
- Straw bale walls can be carved with a knife or chainsaw. Openings around windows or doors can be bull-nosed to a nice radius. Bales can also be finished to a sharp angular edge. Niches can also be carved into the bales.
- 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.
- Straw bale insulation is the most effective in climates where heating and/or cooling of the home is essential for comfort.
- Straw bale homes can be beautiful as the natural material lends itself to multiple architectural styles.
Disadvantages of Straw Bale Construction
- 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.
- If straw bale building codes are not part of your local codes, it may be a bit more work to get your plans approved. Nairobi by-laws recognize them as temporary structures so occupation certificates may be a potential challenge..
- 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.
- Areas of extreme humidity and rain like Mombasa and other coastal towns my not be appropriate for straw bale construction.
- 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.
- If straw bales are not available near your construction site, the cost of shipping them, along with the potential pollution from the transportation, must be taken into account.