I will be building a home that is approx 1328sq sq feet with ICF exterior walls.  It will have a standing seam metal roof.  My GC does r60 blown fiberglass attic insulation w r38 batts in vaulted area.  Is this sufficient for the roof insulation and also is this considered a green method of instulating the roof?  If not, can someone offer up an alternative I can use instead if it is not?  Thanks !!

Fiberglass can be an effective way to insulate, proper depth and sealing is key. If being "green" is your top priority, you can use petrolium free spray foam insulation to the underside of the roof, or blown in cellulose can be considered "green". There is also recycled denim and other green products new to the market but I have not used them in attics. The spray foam is my personal favorite because it not only insulates, but seals the cracks and crevices where air can infiltrate, and THAT is the major enemy. There are a fair number of companies that use soybean oil or other bases to create their spray foam. The spray foam does however cost more. I've seen quotes where the spray foam was double and one was even triple the cost of fg, but it is a superior product and prices vary greatly by region. If it was my home, I'd do spray foam insulation as I feel its the best in air sealing and insulation. Good luck with whatever you decide

Spray foam, urethane, is the way to go. Where you have plenty of space you could spray foam a couple inchs and blow in on top of that.

I agree that spray foam is a good insulator that gets all the little cracks. However, for a new build I am not a fan. If regular wood trusses are used the wood will still be green and therfor will dry out in a year or so seperating itself from the spray foam and creating cracks or insulation voids. If you really want spray foam ,let your build settle completely and then come back with spray foam.
Again, not saying its baad just needs to be applied at the wright time.
Cheers!

2 cents: I would avoid fiberglass. Spray foam is much better and many brands have enough flex to eliminate the problem with wood shrink and warp. You main goal should be air infiltration -- any whatsoever and you have an equivalent R value of zero. Don't want to go off the deep end but it's pretty easy to build a low R value house that performs much better than a high R value house. This is due to the unfortunate nature or process of the R value test itself -- which is done in a vacuum. REgards.

Here I go again! Why not just put a SIP "lid" on your ICF walls, and not worry about wood truss, and/or rafter, shrinkage, air leakage, etc ?

Use a premium fiberglass like Certainteeds Insulsafe or Guardians' Perfectfill. These fiberglass products have a higher R-value and can be blown behind a pdoduct like Polyweb fiber.

Respectfully suggest you look up how R value is measured. R value doesn't always help any of us arrive at the best solution since it's only a third of the thermo. High R value do not always mean good performance. Despite building a well built sealed attic with foam you would still find convection melting snow all along the studs of the roof trusses. Obviously, in this example, the roof is conducting heat through the studs. A SIP roof is the only way to avoid this without building a SIP roof on site of sorts. You will need to build a roof that reduces convection (no leaks) and conduction (no significant amount of wood connecting inside and outside surfaces) and simultaneously - at least compared to the better SIPs you will also need to add a radiative barrier (with air space to keep it working correctly). If you are into building the best system i hope you will jump on board.

Basically the same is true for the walls. If you want to avoid the conductive nature of wood (R of about .6 to 1 per inch for about 20 percent including headers etc.) you will need to go to extremes to stay in the game. To avoid wall conduction, you will then need to build two walls (that generally do not touch) and fill with insulation that does not allow convection (something that fills all the gaps -- any leak whatsoever has an R performance of zero in that area). Wood will need to be heavily chalked -- perhaps several cases for roof and wall (with good chalking). You might also add a radiative barrier to the walls to while your at it. You'll stiff forfeit the thermal mass. Once you go to all this trouble your costs will exceed the SIP roof and ICF wall.

Not on my house. Next time we have a good frost layer on the roof I'll take a photo to show it. After a cold night with a heavy layer of frost on the roof, the overhangs and the uninsulated roof over the porch clear off long before the insulated part of the roof does. I have 10" of Icynene on the underside of the roof deck. My attic is sealed and is the return duct for the heating unit so it's the same temp as the house proper.

dmaceld, My mistake i should have clarifed the thickness of the foam -- here we have to requrest that the studs be fully covered (and sometimes this is actually code related -- where they don't want you to cover them). This is unlikely a problem for you with 10" of foam :) At any rate, although you don't come out and say it I would be willing to bet that your roof trusses are fully covered with foam (unless you used all 2x12s). ;) I have heard that this approach (all attic return) is top of the line in comfort as you can literally have a return in every room to the attic if desired. Regards.

You're right on!

Get the salesmen out of these blogs. You really ruin the content and discussion. So how does it work? If you pay for a pretty lil ad in the top corner do you get to speak your mind?

Your like wall paper, or white noise - completely irrelevant.

SIP this...ICF that...Foam this...Cellulose that. Why can't all of you guys get a long?

There are people looking through these blogs looking for genuine application advice and your filling their heads with nonsense.

Air seal the house - bring in mechanical ventilation. Nuff said.

Our 5 year old ICF home, 1.5 story, 3100 sq ft, standing seam metal roof, has Sealection500 spray foam in underside of the vaulted ceiling (28ft high) and a small layer of spray foam in the 2 regular attics, with blown-in cellulose on top of that.

At 90F outside and the t-stat set to 77F inside, the interior ceiling temp at 28ft shoots at 79F.  In the master bedroom, with the attic and 10ft ceiling, it shoots at 78F.

I would not do it any other way... except maybe a sealed attic next time...