I've been reading the forum for some time as I try to learn from others' questions.  My project is a couple years out, but taking my time in doing research on materials & techniques.  That' a bit unusual for me as I usually just jump in and do it and take care of any mistakes later.  I guess patience comes with age?  Having the topo survey done now.  Have a meeting with a local engineer in 2 weeks to discuss particulars for the area.

Project house will be in Northern NM at 8900 ft, 2 stories into a hillside (garage and one set of bedrooms), 2 stories on top of those but setback somewhat onto the hill top. 

Radiant heat, AC not needed here.  Solar exposure is excellent so will incorporate that.  But the view to the north is unbelievable and will have windows there to take advantage of that as well

I have pretty much decided to use ICF for the garage and second level as they will be partially subterranean.  Thinking of Rastra at this time.  Fabricated 3 hours away, fire resistance in a region that could see a forest fire and as this will be primarily owner/builder, the exterior may see high UV's (strong sun) before skin is finally on(read as "I might take a while to finish the exterior").  Is there sufficient load bearing capacity for two more stories above with a waffle system like Rastra?  Any other comments so far? 

For the 3 and 4th stories, I'm not sure whether to stay with the same or switch to SIP's.   High heating degree days, fair amount of wind.  Which would offer better insulative performance?  Certainly like that SIPs can be prefabbed and installed quickly, but again I like the fire resistance of Rastra.  I thought I had read somewhere on the forum about a climate such as mine (elevation and cold temps) that one should not consider ICF's?  Or am I dreaming?  Any advantages to sticking with what is already being used or changing to SIP's for the upper stories?

Thanks in advance for any thoughts and suggestions.

LarryT

If you are considering Super Insulating or cost is an issue, go with SIPS. If you have a desire for strength and security, go with ICF's.


You may be dreaming. What you probably read was that you wouldn't receive the benefits of thermal mass in ICF's in a cold climate. You will however have the benefit of very low air infiltration and the the base R-Value of the forms. You can always add insulation to the inside of the ICF's to get them up to Super Insulating levels.

It IS the issue about thermal mass as I now recall with your reply.  I have to think through some more and review a table I recently saw that provided insulation values with and without considering thermal mass.

Thanks!