Timber Framers Guild Forums General Straw Bales & Other Enclosure Systems housewrap and natural enclosure systems

I'm a fan of 15 lb felt. It has a longer track record and is much more forgiving than tyvek or typar. Check out:

http://bct.nrc.umass.edu/index.php/publi...ation-barriers/

and read everything at:
http://www.buildingsciencepress.com/