Cool building material

[barefoot]

I just heard about this stuff called RASTRA which looks like it would be great for building a studio. Supposedly it's been around for 30 yrs, but it's news to me.

http://www.rastra.com/wi_ra.htm

It's a permanent recycled porous styrofoam former that you fill with a reinforced concrete "skeleton".

They say is has both excellent sound isolation and absorption properties. On top of that it has great thermal insulation. And since the styrofoam is porous the concrete penetrates into the former and gives the whole thing a four-hour fire rating.

Pretty cool. It's probably expensive as hell though.

barefoot

[M.Brane]

Thanks for the heads up.

That reminds me of a place in Santa Monica called "Syndesis" that makes stuff out of a mixture of concrete and various plastics.

[Todzilla]

This is a kind of building technology known in the trades as "Insulating Concrete Forms." I researched it extensively in hopes of building my house out of it. I didn't find anything particularly damning about it, but we went with traditional wood frame. There were several things about it that steered me away.

It costs about 10% more than traditional methods. This may not be a huge deal, but when building a $300K house, that's a chunka change. I think much of the difference is in fixed cost of getting a concrete pumper to come and mix up a special blend of aerated concrete, so if you're talking a smaller scale project, the costs are more considerable.

It is hard finding a good builder who will try cutting edge stuff like that. Most builders have an entire business model around known building approaches and estimates based on those. Further, they must guarantee the finished product, which means they have to feel very comfortable with it.

Resulting concrete walls are not easily cut into or changed. If you want to add a window, door or addition, it is not easy to alter.

As with any new technology, there is not a wealth of historical data on how it weathers the years and elements. Traditional methods aren't necessarily better, but they do have a richer history of performance and presumably the kinks are worked out.

On the plus side:

ICF has tremendous sound insulation capabilities
ICF has great energy savings
ICF can (theoretically) be done by owner builders
ICF can easily be used to make non-traditional shaped footprints (e.g., non parallel walls are easy, although roof will be a challenge)
ICF allows myriad siding options.

Do a Google.com search on "Insulating Concrete Forms" and you'll get lots of different vendors.

[barefoot]

Great info TodZ!

Yeah, there are pros and cons to everything. But from your description, it does still sound as if this might be a good choice for the special purpose of studio building.

Some very common and traditional materials like concrete block have similar "post-modification" issues and are certainly not very good with respect to acoustic properties. So you're probably going to spend an extra 10% or 20% enhancing these properties when using traditional materials anyhow, no? Plus, I really like the idea that these forms are light, modular, and seem pretty well suited for the do-it-yourselfer.

Do you agree when you limit the scope specifically to studio building?

barefoot