I studied my insulation options on my new house for many months and here were my conclusions:

1. Sealection 500 foam for the entire envelope on my entire house would have been about $12,000.

2. I am not sold on the "envelope" concept. I don't see how it can be efficient air conditioning the huge attic that I have with a 12 pitch roof. I read numerous real world studies and found the actual cooling load in a house with the envelope is actually more than a house with good ceiling insulation and ducts that are not leaky.

My HVAC contractor assured me that his R8 flexduct won't leak and all seams are sealed up with mastic. Some of the duct is actually between floors and in other conditioned space anyway, but maybe only 20% of it.

I went with sealection 500 in the walls and cathedral ceilings. Everywhere they put OSB on top of the joists for HVAC access etc has foam on the bottom side of it. All walls with attic exposure have foam in the wall cavity plus the backside foamed in the attic to stop thermal bridging on the studs.

We put 1/2" R3 rigid foam on the outside of the wall sheathing (osb) to reduce thermal bridging of the wall studs.

The foam contractor sealed all openings leading to the attic, and he also foamed around the windows and doors. They spent many hours calking the bottom plate and every seam between studs, like where there are double studs.

The foam went in, it was a massive mess and lots of work. They spray it and it expands thicker than the wall and they use some kind of rubber grinders to bring it back flush with the wall studs. They carried at least 20 huge trash bags of wasted material with them, saying that it is recycled somehow.

There were some voids, the stuff is very hard to control, so they come back with a different foam and fill in these voids where they didn't get the foam where they wanted it.

The foam contractor also subbed out the rest of the insulation job, with no markup. This involved putting in baffles between each rafter and foaming around the base. This is to keep the loose fill insulation from getting back into the eaves and spoiling the ventilation.

The front side of the cathedral was 2 by 12s, which are 11.25" thick. They put 6" of foam in that and declared it sufficient, but I had them put 5.5" batts on the bottomside of that. Why not get all you can get in there while you're at it.

I micro managed the project, pi$$ing off the isulation contractor at times but I have been planning this for a long time and it was by golly going to be done right.

For example, they wanted to baffle every other rafter and I insisted on every rafter. Then when I inspected their work I found that they had separated the perforations on the baffles and put only half in between the rafters. Clearly, the baffles are 22" unseparated, designed for the gap between rafters on 2-foot centers. You are supposed to pull them apart only for 16" on center or other smaller gaps. He said "we can rip them out if you want". I said "I do", and they did, and now its done right.

I also found about a 6" round void back in my fireplace chase after they had left. I called and they came back and filled it in, even though it was hard to get to. All in all, they did a great job, although I must say it does not produce a perfect monolith like I thought, but rather requires some work to get it right. And, it makes a HUGE mess. The crew took about 4 days on my house, and thats just the foam. The loose fill has not been done yet.

My entire job with the extra batts and stuff I had them add, plus interior wall batts for sound insulation was $8500. There are only 2200 square feet of living area, but lots of porches, cathedral, big walls up in the attic, plus I sealed off a section of the attic for cool storage. The part thats done was $7200. The remaining $1300 is for the loose fill that will be done later, after the electrical is all checked out and such.

We used the radiant barrier decking and foamed the underside of it on the cathedral because it was easier for the decking crew not to have to worry about which kind of osb to use on which parts of the roof. Its only about $3 per sheet more and it was maybe 12 or 14 sheets we foamed.

I have read about a method whereby you staple the baffles all the way up to the ridge vent and then spray the foam to the underside of the baffles. That way, you get the foam, the radiant barrier, and the ventilation too. We didn't feel this was necessary.

The foam is now covered up with drywall except the attic part of it. I like it and think it is going to be great. The insulation contractor would liked to have done the entire envelope and I explained to him I wasn't sold on that. In the bidding stage he seemed insulted that I would doubt his claims and it sounded like he didn't really want the job if I was not sold on the product. The fact is that I AM sold on the product, just not the whole envelope concept, or at least not enough sold on it to spend another $3500.

Sorry, this was kinda long, and I don't have any real world results yet as we are just in the taping and bedding stage, but will report later.