What is a straw bale building?
Straw bale buildings have super-insulating walls made out of stacked straw bales. In most jurisdictions wood or steel framing is integrated into the walls as the structural support of the building, though historically straw bales have acted as the building structure. Straw bales come from a highly renewable and environmentally friendly resource – most commonly the straws used are leftover stalks from California rice crops. Hubbell & Hubbell Architects has designed and permitted over 40 straw bale buildings in San Diego County and is currently working on the first permitted straw bale home in LA County!
The exterior walls of these structures reap many benefits that surpass walls made of conventional building materials. Strawbale walls that are plastered provide superior insulation and thermal mass which helps mitigate temperature swings. Other powerful insulation materials such as fiberglass, foam or double wall system are high- embodied energy materials. They require more energy and resources to construct than straw bale walls. Insulation and resistance to airflow are the key to energy efficient building and durability. Plastered straw bales are airtight and eliminate the need for drywall, wood and paint which are also high – embodied energy materials. Lime – cement plastered straw bales provides 2 hour a fire rating. This is twice the rating of a stuccoed wood framed walls. Straw bale construction proved to be incredibly resilient in recent fires in the western United States, sometimes being the only home left standing in an entire neighborhood. The straw bales provide a less hazardous and more earth-friendly material that creates a beautiful, strong, and healthy space to live.
Benefits of Building with Straw Bales
- ENERGY SAVINGS on heating and cooling. Plastered straw-bale construction results in insulation ratings (R-40 to R-50) more than three times greater than is usual (R-12 to R-15) in typical dry-wall construction buildings. These energy savings for space cooling and heating continue to accrue for the life span of the structure.
- FIRE-RESISTANT. Plastered straw-bale structures enjoy considerably greater immunity to wildfire damage than other kinds of building. If the roof composition and sources of exposed wood such as beams, doors and window frames are made fire-proof, a straw-bale constructed building can survive firestorms that would consume other structures.
- OWNER-BUILDER FRIENDLY. The wall raising can easily be done by the owner and friends, in a modern version of an old-fashioned barn raising. Besides realizing savings on labor costs for this phase of the project, owners can have the satisfaction of living in a structure they have built with their own hands.
- INEXPENSIVE, RENEWABLE MATERIAL. Straw is an annually renewable agricultural residue often considered a waste product and therefore both inexpensive and easy to acquire. Although wood is also a renewable agricultural material, its renewal cycle is longer and it is considerably more expensive.
- REDUCED POLLUTION. Straw is produced by photosynthesis, a natural, non-polluting process fueled by solar energy. Substitution of straw for the raw materials required in making the most common types of wall-insulation material saves processing energy and reduces the use of oil-based fuels.
- REDUCED PRESSURE ON FORESTS. Substitution of bales for lumber could relieve pressures to log old-growth forest and scenic recreational areas.
- REDUCED HEALTH HAZARDS. Substitution of straw for fiberglass insulation materials avoids health hazards for workers involved in its manufacture and placement.
Photo credit: Pavlina Kubicek & Arnel Garcia
Contact us if you would like to build a straw bale home for yourself.
Check out These Projects:
California Straw Building Association (CASBA)
International Straw Bale Building Registry
Straw Bale Testing Information