I am building some walls for a vacation home and I am trying to employ the Building Science Corp’s Build America methodology (for very cold climates).   Their website shows some wall section drawings where the foam board is sealed to the top and bottom plates, and others where it isn’t.  In both cases, the drywall is sealed to top and bottom plates.

I plan to use latex caulk as the sealant and to insulate with blown cellulose, but I’m not sure if I should seal up the exterior.  I’ll be using 1″ T&G (blue) foam board with OSB T1-11 siding as the sheathing and finished surface (at least for a while).

Does anyone have experience with this technique, or know how it is meant to be done?  I don’t want to trap moisture in the walls, so I’d like to get it right.

Your help will be greatly appreciated.

Rich Bartsch