We are building 2x6 walls with 1/2" OSB sheathing and adding 1" of poly iso foam board over the sheathing. I know that we can tape the seams on the foam and that would be our drainage plane/vapor barrier, but the cost of the tape to seal the seams seems to be higher than the cost of Tyvek.
Our bulding supplier suggested we cover the foam sheathing with Tyvek instead of using the tape, and a siding supplier said we need to have tyvek on to maintain warranty on siding.
My DH is concerned since he has read that house wrap will degrade quickly if left exposed to the sun, and it might be not be until spring before we get around to side the house. So he is wondering if we should tyvek over the OSB, then add the 1" foam board on top of the Tyvek ot protect it.

Would that create a problem to put the Tyvek between the foam board and the osb?
Right now the windows are supposed to be installed over the foam board. If the Tyvek is in between the foam and OSB does that mess up the flashing details for the windows?

Thanks for any help.

Well now, I don't know much about you and your area, but I do know what sort of stuff works well in our part of the country.

What sort of tape were you pricing out for sealing the foam? We generally use Tuck Tape out in this part of the country. Sticks quite well (when it's warm), and is designed specifically for sealing in water/air barrier applications - works well for foam and Tyvek. I would reccomend taping both the foam and the Tyvek, however taping the Tyvek alone would be satisfactory.

As far as the degradation of the Tyvek, we usually use Typar...it doesn't seem to rip in the wind if it's left for long periods of time on a house, however that being said, I framed a house 3 years ago that was left in Tyvek for about 8 months, and I couldn't tell any difference between the new stuff and the old. Tyvek on the outside of the foam would also be good (if your flashing detail allows it), because your Tyvek can run up and over the windows rough opening, which will seal the rough opening against the inevitable moisture leakage that will eventually occur around the window.