earthaven- We're trying to be as energy efficient as possible (tho not in the LEED program range) and found that double hung, aluminum clad exterior/wood interior windows had a higher U value than all wood windows. (Perhaps because metal is a better conductor of cold/heat? I dunno.) We decided on Eagle brand double hung, low E, Argon filled, alum clad exterior, wood interior with a U value in the 35 range. I am still second guessing our decision to go with clad vs. all wood, but we wanted aluminum for the durability (we are in northern NY on a lake and get a lot of wind, snow and weather). They are ordered and will arrive and be installed the second week of January, so I can comment on product quality then. Congrats on your very cool and highly personalized home. sandyponder

We built all-ICF in upstate SC, and the performance is remarkable in our fairly mild climate. Given the same foam thickness, either method should perform about the same. The only big advantage I can see for ICF is that it has fastening strips embedded for attaching drywall and exterior siding, if desired. I think ICF does best in moderate climates, with performance falling off at the extremes of temperature. While building our house, I measured the core temperature during the coldest part of winter, and it was about 13 C. (55 F.). I imagine in a very cold climate, it would be much lower than that. Our small house has about 100 tons of concrete in the walls. I'd hate to try to heat that significantly. Here, our ground doesn't freeze more than a couple inches. Our winter design low is -7 C. (20 F.), and in the summer, it is often 34 C. (93 F.), occasionally much warmer, and rarely gets below -18 C. (0 F.) in the winter, and is almost always above freezing during the day. I read an article measuring the true R- performance of ICF in different temperatures. During the shoulder seasons, when temperatures are rather mild, it can perform as high as R-66, while the 'true' R-value is R-24. That's why you sometimes see inflated claims as to its performance. For a very cold climate, you'd want extra foam on the outside of the foundation, plus careful attention paid to isolating the concrete core from the cold ground temperatures. They do make ICF with different thicknesses inside and out.

L S if the contract states R15 you should be getting R15 simple as that. My most recent house I did had a mix of R15 and R13 due to budget reasons. Trying to finish the house under 100k including land. Speaking of budget your contractor is trying to save money by using lesser insulation and the staple part, I FIRED a guy of my previous job because he did that. The crazy thing was after I pointed it out to him he said not to worry that he seen it done worse. He got FIRED and never came back. As for the R15 insulation it is a little better true, it also has a side benefit that people don't talk about but it matters to me, it mutters the noise better and the house feels solid and quiet. Here is a shameless plug for my video :-) I talk about the insulation and price of it as well so you get an idea. Last thing get the insulation you agreed on it makes a difference. P.S. I also used Hardie siding.

The number 3 option has the potential for failure as you mentioned. To limit this I would use more holes and try to just seal against the the framing and outer casing. This would leave an air gap, use less foam and still create an air seal. Invest in a foam gun. There are 2 part foam kits that are for filling wall cavities that do not need air to cure. You could also have a company come out and dense pack it with cellulose or the foam. The benefits may not be that great if your walls are not currently insulated .