My wife and I are still in the design lay out on our 6998 Sqft one story home in Houston Texas.

We like the Idea of ICF wall but notice lots of people with ICF wall build stick roofs. Seems like nobody wants to do an ICF roof if they do it mostly flat roof. Would a metal roof what I been hearing it cost 30% more to do then asphalt Shingles which does not sound like a bad idea plus the roof is rated for F4 tornado which is over 200mph wind and it reflex most of the sun light so it should help with the energy bill. This would seem the best option metal roof with ICF walls. My wife love the idea of differnt colors and styles.

What do you guys think?

Thanks!

I'm not sure what you mean by a "metal roof" -- metal shingles or panels, metal rafters (is there such a thing?), steel\metal ICF?

Currently on my ICF plan I have ICF walls and floors, stick rafters with plywood sheathing, vented attic with foam insulation to at least R70 and metal shingles. Basically a "conventional" roof (6:12 pitch or thereabouts) but the shingles are supposed to last 50+ years instead of 20 or so with asphalt. I've gone round and round on this topic though. The factors for me are the aethetics (flat roof == ugly to me), ability to insulate to R70+, maintenance free for as long as possible, and the roof\truss system to last 200 years or as long as the ICF walls and foundation. I would also like it to survive the occasional nuclear blast or end-of-world event but that's optional :)

I considered a pour-in-place ICF roof but want a slope greater than 4:12 pitch (for looks and practicality - flat roof requires maintenance to avoid leaks) which isn't doable with ICF unless you go pre-cast (or ground-built) and lift with a crane. ICF roof seems like overkill for what I need -- I don't live in a fire or hurricane zone. Plus even with ICF roof I still want metal shingles for the look (and prevent water from soaking in).

I also considered a metal SIP roof but I have a few angles coming together and that would be a bit tricky for SIP but doable. It would still need metal shingles as the exposed SIP metal is ugly and not very durable. Also due to the vault there is more surface area on a SIP roof (or ICF) so it is not as easy to get as efficient as a unvaulted, vented stick-built roof. My primary concern is heating, not cooling. I don't really want vaulted ceiling aethetics so if I had a SIP roof then I would have to spend money to add in a flat ceiling. Also getting a super-high R-value requires two layers (to my knowledge) which is costly and not sure how the fascia area would look (two foot thick roof).

I also considered stick rafters with standing seam metal and no plywood sheathing, but I just don't like the "commercial" look.

I suppose if I had unlimited funds, I'd explore having an ICF flat ceiling on top floor with concrete 6:12 roof, fill in the whole thing with foam, waterproof\seal the concrete roof, and then add metal shingles somehow (not sure how they would be anchored).