Aerated Concrete--Why You Can't Have a Bullet Proof Home in CA. An Illustritative Tale

Today on, there was a little piece on the non-acceptance of aerated concrete material pursuant to the California Building Code. 

According to CNN:

AAC is a mixture of sand, water, lime, portland cement and aluminum powder that is formed into blocks and cured in an autoclave, a sort of industrial pressure cooker. It has been used in Europe, where it was invented, for more than 70 years.

Besides being fire-resistant, AAC also deadens sound, is energy efficient, is impervious to termites, is bulletproof and waterproof, generates no waste in its creation, and can be recycled, its fans say.

We all know how important it is to live in a green, not to mention bullet-proof, structure, so one would think that a progressive state like California would allow for the use of this material.  Not so, says, because AAC has not been tested for its seismic resistance.

"Autoclaved aerated concrete cannot be used to resist seismic forces because it has not been seismically tested," said David Walls, executive director of the California Building Standards Commission in Sacramento. The restriction is based on guidelines from the National Earthquake Hazards Reduction Program, he said.

The AAC issue is illustrative of the issues which accompany incorporating new materials into traditional building code structures. 

First, you have the issue of overlapping regulatory interests, like promoting energy efficiency and preventing buildings from crushing people during earthquakes.

On top of these regulatory interests, you have administrative considerations.  Most states adopt the International Building Code or some form of it on a regular schedule.  New materials and products may emerge as salient between upgrades to new code systems.  In addition, not all of the code may be adopted.  In this case, California adopted the 2006 IBC without the companion housing code which would have included acceptance of AAC in seismic areas, according to a source. 

Finally, there are the political considerations.  From the AAC example, manufaturers of competing products may intrude with acceptance of the provisions of the building code which allow for new materials.  

Greening the building codes is not a simple task--competing administrative, regulatory and political forces must be managed and balanced.  Even with the best of attention to each of these considerations, there will always be examples like AAC which fall through the cracks. 

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Comments (5) Read through and enter the discussion with the form at the end
Christopher Hill - June 11, 2009 5:11 PM

A great take on tradeoffs, thanks Shari. No wonder you're in the top 50

Mike Sealander - June 15, 2009 7:40 AM

AAC has been available in other parts of the country for some time, and I assume the vendors are familiar with the regulatory landscape here. It's up to them to get tested, just like straw bale, or SIPS panels.
One way to look at the multijurisdictional nature of the country is to say that every product has potential benefits, as well as unintended consequences, and to champion a product because of stellar performance in one metric without a vetting on other metrics is risky.

bob henderson - July 30, 2009 8:46 PM

I have searched for hours to find the Fl. acceptance number or the Fl. NOA for AAC. If anyone knows the answer please send it to me @ I used this material to build a break room for one of the municipallities but they didn't require the noa, Manatee County does.

Concrete In Michigan - December 29, 2009 3:39 PM

"Besides being fire-resistant, AAC also deadens sound, is energy efficient, is impervious to termites, is bulletproof and waterproof, generates no waste in its creation, and can be recycled, its fans say."

Sounds like a good material to me!

Dionisio - June 29, 2010 11:00 PM

Great blog Shari!

In Japan, AAC or ALC (Autoclaved Lightweight Concrete) is largely used. They fix the ALC boards in only two points and let it move if there's a shake.

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