Ytong AAC

[Mark]

Has anyone built in Puna with Ytong blocks? I will be building in HPP and am very interested in exploring this option.
Thanks,
M



Mark

[Green]

Just curious,but what do ytong blocks look like and where do you purchase them ?

[Rob Tucker]

AAC, Aerated Autoclave Concrete has been around for about fifty years. Originally developed in Scandinavia I believe. The material, under a variety of brand names, produces a very high quality building with typical European efficiency. I am at a loss why AAC does not have a larger market share and is such a sleeper in the world of alternative construction methods.

Every attempt I have made to contact companies over the past fifteen years has been responded to barely or not at all. So that slowed down my experience. I guess I got the sense that with AAC manufacturers all they wanted were very large commercial and industrial projects and residentials, where I work, was of little or no interest.

Perhaps that has changed.

The autoclave process does not lend itself to local small scale production.... so production seems to be confined to large market demographics. That may make it less available to an island location.

Having a concrete block that you can drive a nail into appeals to people (who like nails for some reason?). But they are generally easy to build. Well insulated. Well engineered. And durable to the max.

If I had a supplier I could depend on Castleblock would be happy to handle AAC products. I just never found that source. So I have carried a somewhat similar product called Rastra. Developed in Germany it is similar to AAC in that the blocks are malleable and instead of aeration (injected air bubbles) the concrete has an aggregate of recycled polystyrene beads.

This Rastra material is what my home is made of. It is 4 hour fire rated with R-30 insulation and a projected lifespan (without maintenance) of 200+ years. My building costs (owner builder - and I mean owner built) were about $65 psf.

If it's of interest I can show it to you sometime.

[StillHope]

Rob,what #4 means practically as far as fire is concerned?
Very little damage?
I am wondering why they are not building mostly that type of houses in the wild fire zones (CA ,for instance).

And I am going to bug you again on the price difference - what you think your house would have cost if you had used a GC?

[Rob Tucker]

4 hour fire rated means that the materials were tested with a 2,000 degree flame test for four hours and the fire did not structurally compromise the wall. There was no toxic out gassing or penetration of the wall by the fire. The test wall survived a 4 hour fire.

As for pricing with a GC? If you were to ask 10 different GC's to price your wood plan you would get 10 different prices. A lot has to do with finishes - which would be the same no matter what structural system was chosen. A lot has to do with the GC paying legal wages and insurance or not.

A lot has to do with desired profit and actual overhead. A GC with seven kids and three ex wives might be charging more than a single guy.

I would suggest an ICF home of simple design and finishes to run about $150 psf. I would suggest that a similar project in SIP would be about $135 psf.

[StillHope]

Thanks,Rob!
Seems like you have a very good stuff.
About the GC price.Mine has 5 adopted dogs.
I think I am in trouble![]

[Mark]

Rob,
Thanks for the great info on this. I emailed Michael Hofman on O'ahu for information, as well ( mhe-international.com ). He replied with some good info and said an AAC house would generally be about 10% more than stick-built.

I am currently in NYC but will be in Puna around Christmastime. I'd be very interested in seeing the Rafta house and talking to you about it.
Thanks,
mark

Mark