I live in climate zone 5 (central PA).  I need a Class II Vapor Retarder on the warm side of my exterior wall assembly.  House was built in the 1960’s.

The existing exterior wall assembly consists of woven house wrap, 1/2” fiberboard sheathing, 2×4 studs, Roxul R15 Insulation, Vapor Retarder (TBD), and 1/2” drywall.

My question is…which interior smart air barrier is best for my application?  Siga Majrex 200, Pro Clima Intello Plus, Certainteed Membrain, or another product?

A more air tight envelop is my goal and I plan to address the exterior issues in the spring…but want to take the opportunity on the interior side right now.

Thanks for your input!