Hi i live in Tennessee and it gets cold in the winer but not Chicago cold its in the teens at night and 30's during the day typically and i am wondering if i have tyvek on the exterior if i need to put vapor barrier over my interior insulation before i drywall
The purpose of tyvek is to prevent exterior sources of water from penetrating the framing while allowing water vapour to escape. A vapour barrier prevents interior moisture from entering the insulated framed walls and rendering the insulation less effective due to excessive moisture. Moisture transpiring through the framing will also condense at the dew point. The water would create conditions ideal for mold growth. This is the bases for a vapour in colder climates.
When using Tyvek on the outside and a vapour barrier on the inside due diligence in preventing water from penetrating the structure around door and window openings is essential.
Read about the Vancouver leaky condo crisis. It brought about a change in the B.C. building code