duct tape is worthless. i will lose grip in months. use a product designed for foam.

Duct tape has no application in construction. It should not even be used for sealing ducts because it just falls off eventually.

If you want help designing your exterior wall you should reveal to us the rest of the assembly and the climate.

Here:
vanmicnatlog (My Page) on
Sat, Oct 4, 08 at 22:26

I am new to posting on any forum. I have been browsing (addicted to) for several weeks. We are building a new home and just wanted to verify our plans for insulating our new home. We have 2 storys (1400 sq. ft, 800 sq ft and full basement 1400 sq. feet. 2x6 wall construction. In the basement i plan to have 2 inch foam, 2x4 wall and batt insulation. On the upper levels, i was just reading the "Gimme shelter" and other sites. (I would love to have spray foam, but we are paying as we go and don't think we will be able to afford that option)
Have 3/4 inch foil faced foam on entire exterior

Would it be ok to:

put sheet foam between the studs, then blown in celullose in the wall cavity.. will caulk and spray foam all crevices and around electrical outlets.

Attic/ ceiling: we have some attic space, some cathedral ceilings. Will do blown-in in attic spaces, and was just thinking about what to do for the cathedral sections. What if i use stack foam sheeting in the rafters (ten inches). Will have rafter mates for ventilation. Or would we be better off using batt insulation in the cathedral section.

what about that foil faced vapor barrier, can that be used for holding in the cellulose insulation?
Any help is appreciated.

Thanks, i am in northern michigan, zone 4. We are building a 2300 square foot 1 1/2 story home. 2x6 wall construction, sheeted w/ osb, vapor barrier and the 3/4 inch foam on outside. It will be covered with vinyl siding and stone when it is finished. I am very concerned about my insulation because the ceilings are high and fuel prices are rising. We will be using an outdoor wood stove for the most part w/ propane furnace back up. I would love to do the spray foam insulation but we are building ourselves and paying for this build as we go and i am not sure that we will be able to swing that. My original post in the other forum was asking if i could: use the foam on the exterior, foam and caulk all cracks and sill plates, beam etc(not a builder...just the researcher in the family) in the framing, use blown in insulation in the walls and attic spaces///// i have read much on here regarding the r value necessary. and in the living room and bedroom that are cathedral ceiling, i was thinking about using the ....duravent, and stacked foam sheets that were sealed with spray foam... from a can to get a higher r value in the 2/10 area of the cathedral. am i on the right track or would i be better off w/ batts. do you have any idea where i can purchase that tape for the exterior joints in bulk or large quanities, it was like 11.00 for 50 feet, i have LOTS of 50 feet rolls to buy.. depressing.

I am a fan of your proposed wall system. If you use tongue and groove foam board, you don't need to tape the joints. (You'll still need some here and there. Buy Tuck Tape in bulk from your lumber supplier.) Forget the vapor barrier on the inside, unless it is Code required. You could add a wrap between the foam board and the OSB if you want extra air tightness. Forget fussing around the sill plates: have cc foam professionally blown in.

For the attic, you could use a non-vented system, spraying under the sheathing with closed-cell foam, as recommended by Building Science Corp. experts.

Here is a link that might be useful: Roofs

OP: Continue with the exterior foam boards, spray Cellulose in the walls, caulk and foam joints, use your foam board idea for cathedral ceilings. That should be a very tight envelope with a R Value over 20 in the walls.

Worthy: Won't regular Tyvek Tape work for the Foam joints? Or does it not adhere well to foam?

From what I have been told. If you use foil faced foam board, than you must use foil tape for the joints. The foil is a radiant barrier tapping the joint with any thing that is not also a radiant barrier is just a wast of time.