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I've been reading about ICF for a few months now including this forum and its intro. My wife and I are building a new home in CT, and the advantages of ICF have caught my attention (particularly the durability, sound absorbition, etc). However, our architect has no experience with ICF and we have no experience with houses :). To say the least this ICF construction is not common around here, and that worries me. I've collected and sent him all the links I could find.

We are currently at the design stages and the architect is wondering whether our current design is suitable for ICF construction. In particular we have a very large section of the house that has a ton of glass/ is mostly glass (this is a modern house). Some of the benefits will be mitigated (insulation). Some of the questions relate to the aesthetics of the house (see architect comments below). To what extent are aesthetic considerations similar to building a block house (that seems to be his impression)? How do the thick walls affect the design particular for something that is not a colonial (lots of large panes of glass)? Would our use of glass be limited? I've spend a lot evening reading up, but for someone who has never seen an ICF house I just don't feel qualified even trying to answer the e-mail below. Any help is appreciated. At this stage I am mostly trying to assess the suitability of ICF to the design (whole house or part), how much learning I should submit the architect to, etc. And no I don't have a builder yet (though I am in touch with a couple with ICF experience in my area). If this was your house, what would you recommend (we will assess costs later/separately)?

Link to rendering of current design (not done with ICF in mind).

http://picasaweb.google.com/Jason.Marisa/House/photo#5236060101344516354

Architect comments. We really like our architect, but his knowledge of ICFs is very limited.

 

"This type of bearing wall construction begs for smaller (narrower) windows so that the concrete or block doesn't have to span large distances. If there are large spans, there is a great tendency for thermal cracking. The advantages are that this bearing type construction can look very substantial esthetically. 

Given that restriction we are building a model to show how that might look. 

 

But the overriding issue for us is esthetic: how much will ICF limit the window areas? All the examples Ive seen are standard window schemes.

 

We have to get more familiar with this product to understand its nature and limitations."

The ICF industry touts anything built conventionally can be built with ICF, that is true to a certain extent, but certain areas it won't work well, such as extended cantilever areas and as you are describing a wall of windows.

The wall of windows can be done, but at what expense.

I don't know the factors in your area, an engineer will have to review and give you available options and it would be up to you to decide which route you want to go based on finances and benefits.

One thing to consider is a red iron frame for a wall of windows, mind you I am in CA and with earthquakes that would be the best route to go for siesmic strength. Your area may be different.

You don't say what your energy efficiency goals are, if any but here's a couple of thoughts from that viewpoint. When I was doing the heat load calculations for the house I'm now building it became quite clear that, even for high quality windows, 1 square foot of window has the heat loss of 4 square feet of ICF wall. If you're doing lots of glass for aesthetic reasons primarily be aware of the long term heating/cooling cost you are building in. If you're looking at using glass for its solar gain in the winter heating season then I presume you're incorporating passive solar aspects into the design.

If you are doing passive solar there's been a fair amount of discussion on this forum about the advantages/disadvantages of foam on the interior side of ICF.

From what I've learned on this forum and building my own house there's no particular limit on window size in an ICF structure as long as you engineer it correctly.

I think you have a several different situations.  The garage and its second story should be easy to do in ICF.

The lower walkout level, with the exception of the corner column should also be easy with ICF.  The walls on the upper level can also be ICF, but I think that will depend a bit on your floor and roof systems.  Are you thinking concrete?

How high is your parapet wall?  If you are thinking floor to ceiling glass and a concrete roof, you might consider making the parapet walls as upturned beams over the long windows, although the cantilever will complicate that.  As a rule of thumb, your structure depth will be approximately span/24.  It looks like the front to back dimension should be easy to span. 

Depending on how you solve the cantilever and the roof will probably drive the upper level structure.  I would not be surprised to see some concrete or steel columns.  You could probably do it with ICF, but I gather your aesthetic tastes may want a thinner structure.

I agree with your decision to eliminate the mass at the entrance and to raise the roof line.  The clean, contemporary lines are nice.  You will want REALLY good glass since there is a lot on the north. The cantilever is there to provide some shading, correct?  The garage will cut off the late afternoon sun, so your solar heatgain may not be too bad.

Bruce