Has anyone built or is building a home with Rastra Blocks in Southeast Texas?

Real ICF is the best way to go. Easier to handle, less labor, less shipping costs, etc. Real ICF ships easy, stacks easy, handles easy. I've always had good results with ICF.

So Todd, you're saying Rastra isn't "real"ICF? Just how are you going to define that? By what the anachronism ICF stands for, Insulated Concrete Form, Rastra meets that definition. Sure it's constructed differently, but it's definitely an ICF. I've seen a number of structures built with it and it performs fine. It has limitations and advantages. If I was not building two stories below grade I would have used it instead of Nudura, as the reduced amount of concrete, at $180/yd locally would have saved a bundle. You can plaster directly over it, bullnose the corners, create various shapes and forms easier that "real ICF". Just because you are set on a particular form of ICF, don't turn up your nose on something just because it's different.

Nashvegas - actually, no. Rastra is not a "form." It is a building block. Some would say it is just a glorified cmu.

I'll take exception on that. It is most definitely a form! And it certainly isn't a modified CMU! It's a form because it is used to contain the concrete that it is filled with, right? And unlike a CMU which has sufficient strength as it is to be used as a supporting structure, The Rastra FORM, has to be filled with concrete and rebar, like any other ICF.

However you call it, Rastra has more similarities to CMU. Both are heavy blocks, are not easily handled, it is NOT a monolithic concrete formed system, doesn't have attachment point systems, has poor insulation properties per inch of block.

If you placed a CMU next to a Rastra block, most people would think it's a modified CMU.

I don't see the advantages of Rastra vs more traditional ICF with 2.5" of EPS on each side.

Well actually, almost all structural CMU require corefills, bond beams and rebar, just like Rastra.

http://www.icfmag.com/articles/composite_icfs.htm

"The Greenest ICFs might be Gray" I guess we can trust ICF Builder magazine on the subject of nomenclature.
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Rastra is 85 percent recycled polystyrene. The blocks weigh 22 pounds/cubic foot. Yes, waffle core has far less concrete fill than traditional ICF requires. On a green note, however, waffle core blocks have far less concrete fill than traditional ICF. It's called embedded energy, and it matters because the first step in Portland cement is heating limestone to 2240 degrees Fahrenheit.

Less concrete also means more polystyrene. A 12 inch Rastra block is nominal R10 over the apex of the concrete core expanding to R21 in the solid portions of the wall (vs whole wall 23ish for conventional ICF.) As well, the thermal mass effect of Rastra parged with plaster is likely to be a larger factor because the mass isn't shielded by interior foam as traditional ICF is. What's more, you can always sheath the outside with more foam. Buy used foam reclaimed from old Wal-Marts and you' can call yourself the greenest guy on Greenbuildingtalk.com. Rastra is one of many lightweight (cellular) concrete systems. Check out Cresco in Houston http://crescoconcrete.com/liteblok-38/ Nominal R value is 1.3 per inch of wall thickness.

That said, you're going at this backward. First, find an energy modeling software program that uses weather data from your area. UCLA's HEED can get you within a few miles of your building site. It also has standard options that allow you to build a crude model of your home design in proper orientation and compare wall systems with a few mouse clicks. For a lower cal approach, try UCLA's ClimateConsultant which also uses local data to find the best energy strategies for your climate. I'm writing this because humidity control is likely to be job one in SE TX, and wall systems pretty much have zero effect on humidity -- unless the house is so efficient the AC never runs, in which case you might be happier spending your money on a big solar pv array on the roof. Good luck.