Replies

1. 
   Guest_ | Aug 25, 1999 02:09am | #1

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   Just finished the framing on a large (2500 sq ft) house on top of a ten foot high rastra stem wall in Northern Idaho. Have worked on several in the Tucson area as well. Am by no means an expert, but what exactly do you want to know? The company Ener-Grid would probably love to send you some information but I don't have their number off the top of my head. I find it interesting that FHB has not done an article on the material unless I missed it. Heavy, crumbly, dusty work but suitable for lots of applications and good R-value.

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   Norman_Williams_GREENBLOCK_METRO | Aug 29, 1999 09:40pm | #2

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   Ener-grid is no longer in business. Rastra is an airated concrete block. It qualifies as an insulating concrete form. However its insulating qualities are questionable. As the manufactures rep says "it breaths". It's best quality is that it is fireproof. As insulating concrete forms go, it is in the top 8 for difficulty of installation.
   (opinion based on experience of our installers).
   Please tell us about your project. We can help with suggestions of which icf is right for you. You might also want to go to http://www.insualtingconcreteforms.com. There are links to most of the manufactures web sites and an open fourm call ICF TALK.

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   Andrew_Kirk | Aug 29, 1999 11:38pm | #3

   *Fred, I am well along in building a Rastra block house and will gladly share my views. First, if you have the opportunity, go observe the process and talk to the people who actually handle the components.The advantages of Rastra are: your finished building will be quiet, fireproof, exceedingly strong, and - one hopes - easy to heat and cool.The thick walls may also be an aethetic plus.Now the disadvantages. Rastra is not a fully developed building system; the technology is not complete, so you will need to be inventive, which is to say you will take risks. It is slow. In my area of rural California, the building inspector limited us to "lifts" of 4' per pour, or three Rastra blocks tall. So we repeat five times the process of stacking blocks, setting rebar, bracing where necessary, then pumping concrete. Please note that stacking the blocks is only part of the process, and sometimes the quickest part.You can't go out to the local hardware store and buy a few blocks if you run short or change your plan. Rastra is certainly not for the weekend warrior or owner/builder.Construction accuracy is less than wood construction. The blocks are inconsistently sized. Our walls, after six blocks (6 X 15" = 90"), were 89" tall. Variation in thickness and squareness result in need for extra stucco and a lot of shimming to maintain anything like a plumb wall. The blocks also are not always straight, but cutting them in half helps with that.You will need storage for the blocks equal to about the square footage of your building-to-be.Window and door installation and weatherization are big question marks.Very difficult to make changes or remodel these concrete filled walls. Even to hang a picture, towel rack, or bulletin board is problematic.Installation of plumbing and wiring in Rastra is not easy. Again, this is not a complete building system with products and methods fully worked out and available at the corner hardware store.You will need some sort of lifting device unless you cut all the blocks in half. Rastra is a great product for retaining walls, maybe for foundations. Maybe for industrial buildings where exposed conduit would be acceptable and where windows and doors are few.If you want to use it residentially, design your building to accomodate the 15" layout of the blocks; if you have to modify many blocks off the 15' layout you will frustrate yourself no end. Don't believe all the hype. Talk to people who work with the stuff but don't sell it. And carefully weigh those few advantages against the disadvantages. Email me for further info.

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   Fred_Matthews | Aug 29, 1999 11:41pm | #4

   *Project is in Sedona, AZ. My understanding is that this ICF system is used quite a bit in that part of country since they are based nearby. I am mostly concerned about its installation...would love to hear more from those w/ personal experiences, good or bad. Project is a 6200 sf custom home. It borders on Nat'l Forest, therefore fire resistance is of great concern as is insulative value given the wide temperature fluctuations.

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   Mad_Dog | Aug 30, 1999 06:05pm | #5

   *Rastra Block?Is that a section of town predominantly Jamaican?

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   Norman_Williams_GREENBLOCK_METRO | Sep 04, 1999 10:03am | #6

   *Andrew is right on the money. We are GREENBLOCK dealers and installers in North Texas.There are over 40 brands of forms on the market. Some are complete building systems and some are not. Before you make a decision look at several projects. Don't be fooled by the up front cost of the systems. Some boast a very cheap price but you will pay for this in added labor and waste. ( our installation crew has experience with 30 brands )The key to ICF construction is in the installation. We do not sell GREENBLOCK to anyone that has not been trained to use it. Concrete is very unforgiving. Once it is placed that is the way it must stay. For more information on ICF's go to http://www.insulatingconcreteforms.comPS.Watch for an upcoming story on ICF's in FHB. We supplied some of the photos. Regards Norman

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   Ian_ICF_Builders | Sep 11, 1999 03:25am | #7

   *I agree with many of the comments made already....no sense in beating it to death. The success of any ICF project whether Rastra or GREENBLOCK relies heavily on the skill and intuition of the installer. We install all brands of ICF's. Our last Rastra project was stacked and poured this past January in Greenville, Texas. We have built several Rastra and Ener-Grid structures over the years. Here is the e-mail address of the Owner/Builder of this last project. They can tell you about the trials and tribulations that they may have had to endure. We contracted to assist them in the construction of the walls, providing both brains and braun, but they did most of the work. Contact Ed at [email protected] Good luck. Ian

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   Fred_Matthews | Sep 11, 1999 03:25am | #8

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   Interested in learning more about Rastra wall system. What is it? Experiences? What geographical parts of country is it used in? Thanks