MEETS U.S. BUILDING CODES
bottom line is that yes, using strawbales for non-loadbearing infill walls
meets existing building codes for both residential and commercial
structures throughout the United States.
Why is this true? Because
building codes are not written to exclude new or alternative construction
materials and methods. Rather,
each building code begins with an inclusive statement such as the
following from the CABO 95 Preface:
intent of building codes to ensure that materials are used safely and
suitable, not to limit the use of appropriate materials.
The burden of proof is to demonstrate that an alternative
construction method meets the intent of the building code for
durability, effectiveness, and safety (including fire resistance).
This means showing how strawbale infill wall systems meet the
requirements of the building code for insulation value, flame spread,
smoke development rating, and fire rating.
Demonstrating compliance with the building codes is possible thanks
to many pioneers that have dedicated time & money to sponsor
third-party ASTM (American Society for Testing and Materials) tests.
The results of these tests show that strawbale wall systems not
only meet the building code, but in most cases surpass the intent of the
code compared to standard stud-and-drywall construction.
Several States and Counties
David Eisenberg has written
extensively and with great eloquence on how to communicate effectively
with building officials, and I encourage anyone wanting more detailed
information to review his writings on the topic.
I have used the following strategy with success:
Schedule a pre-submittal meeting with the permitting
official to communicate your intentions to build
with strawbale. If they are
not already familiar with strawbale construction, provide printed
information and additional resources.
(Don’t overload with information unless it is requested; like all
busy people, building officials are less likely to review a daunting
pile.) Bring to the
For the final permit submittal, my experience
is that stamped structural drawings greatly facilitate the speed and ease
of the permitting process.
Remember that your building official is your ally not your
adversary, and has the same goal as you: to ensure that what gets built is
safe. Acknowledge your common
interest for occupant wellbeing and safety.
You will create connection instead of confrontation and open a
dialog on how to achieve your common goal.
Be informed or hire an advocate that has experience in
strawbale construction, including how to build appropriately in your
climate. The building official
will generally have more confidence in your project when they know someone
on your team fully understands this non-standard construction technique.
At a minimum, be prepared for the following common questions:
have to date not experienced any delays during the permitting process
using this method of interaction with building officials.
Increasingly, I find that building officials already possess some
level of knowledge about strawbale construction, which was not the case in
this region of the country even 5 years ago.
Finally, I would like to address the issue of adopting existing codes and details in different climates. I design structures in a wet, humid climate with hot summers and cold winters. However, many of the now-standard strawbale details have mostly developed in arid and temperate climates that are not necessarily durable in this mixed climate. For example, I do not recommend using rebar inside a strawbale wall in a humid climate, since the cold metal creates an artificial dew point inside the straw wall. The result is elevated moisture around the rebar, which can lead to rotting the straw over time. Instead, I recommend external pinning or using materials that are “warm”, such as bamboo. Similarly, pea gravel at the base creates an artificial dew point, as well as creating a thermal break along the entire base of the wall. My point is not that the originally developed details are inadequate, but rather that they are specific to an arid climate. So when adopting codes and details in different regions with different climatic concerns, ensure that what you propose will perform durably in your climate.
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