Frequently Asked Questions

Is straw bale appropriate for the Northwest climate?
As always, it depends on the design, but YES it is appropriate in the NW. Not only does Oregon grow a tremendous amount of grain, we have a cold winter climate making a super insulated wall system all the more important. With the right design, taking into consideration the site orientation and the appropriate finish materials straw bale is an excellent choice for this climate.

Can I build a permitted straw bale house in Portland and/or Oregon?
Yes, non-load bearing straw bale projects have been permitted in Portland and the rest of Oregon. There is a section of the state building code that specifically states what is required to build with straw bales. Granted you do not always have to follow the code’s prescriptive path if you are working in conjunction with an engineer, an architect and the plans examiner.

Can I build a permitted cob house in Portland and/or Oregon?
As of February 2009 cob is not a permitted structural system. Recode Portland and Portland’s Green Building Technical Advisory Group is working on this. Cob has been used in 2 permitted commercial buildings in Portland: People’s Food Co-op and The Rebuilding Center.

How much does it cost to build a straw bale house?
Once again, it depends on a variety of factors: design, size, custom elements, location and other material and system choices. On average construction cost range from $150 per square foot to $200 and up depending on the aforementioned factors. The notion that natural building is ‘cheaper’ is true only in cases where the homeowner is heavily involved in the construction, materials are chosen wisely and the building is constructed in a manner to minimize long term expenses like heating and cooling.

What is the best material to build out of?
It depends on location, codes or lack thereof, size, design requirements and technological capacity of the community the building is designed to serve. A look into indigenous building techniques of the area you want to build in speaks volumes to what will likely be appropriate to the site.

What is the R-value of a straw bale wall system?
Depending on the thickness and quality of the bales, how they are oriented and how they are installed wall systems can range from R-30 to R-65.

What is R-value?
R-value is a measure of thermal resistance, or resistance to heat flow. The high the R-value the more insulative a material is.

What is thermal mass?
Thermal mass provides ’inertia’ against temperature fluctuations. For example, for a building, when outside temperatures are fluctuating throughout the day, a large thermal mass within the insulated portion of the house can serve to ’flatten out’ the daily temperature fluctuations, since the thermal mass will absorb heat when the surroundings are hotter than the mass, and give heat back when the surroundings are cooler. In some senses ‘thermal mass’ acts like a battery for heat.

What is passive solar?
Passive solar refers to a building design that uses sunlight for useful energy without the uses of active mechanical systems for heating and cooling. A common example in the Northern Hemisphere is orienting the majority of a building’s windows on the south side of a building so that when the sun is lowest in the winter the sun shines in the building and heats it ‘passively’. If designed appropriately in the summer the sun does not shine directly into the building thereby passively cooling it.

What is the difference between green and natural building?
Green building is the practice of increasing the efficiency with which buildings use resources, such as energy, water, and materials while overall reducing the building’s impact on environmental and human health ideally throughout the lifecycle of the building through well designed siting, construction, operation, maintenance and eventual removal. Natural building is the practice of building using minimally processed, local and low tech materials with a major emphasis on local ecology and social ecology. A natural building involved a variety of design elements: localization of materials, site and size appropriate, non toxic materials, recyclable and salvaged materials, appropriate and high functioning systems and regenerative in nature. The major distinction between these two building types is that Green Building frequently incorporates highly processed materials and high tech installation methods to gain energy efficient performance from buildings, where as a natural building maximized the use of minimally processed and natural materials from the start.

What is the best way to build ecologically?
The easiest way to answer this is to not build at all. All construction has ecological consequences and there is no single solution other than careful and thoughtful observation about the impacts that construction has on people, place and planet. The first best thing you can do regardless of material choice is to build SMALL! Less is more! The smaller and more efficient your house footprint, the smaller your ecological footprint will be. The second best way is to design ecologically and design for the LONG TERM. Design the house with your great-great grand children in mind. Think regeneratively. What will this building contribute over its lifespan: will it capture water, is it passive solar enough to not require supplemental heating, does it increase human and wildlife habitat, is it modular, recyclable, compostable or a burden on the ecosystem when its inhabitants are long gone? All good buildings are the answers to good questions.