Vapor Barrier

[larrybr45]

I have a 1988 mfd. home and am redoing drywall. When tore off, I have batts of R19 insulation between studs, but NO vapor barrier or paper on the inside. On the outside I have siding and some cheap board material (=-3/8) that might have vapor barrier properties on it nailed to stud. I plan to tear outside off and put on either 3/8 or 1/2 osb, cover with TYVEK, and then put new siding on.

Question is, knowing how I will ultimately do this (with tyvek on outside) should I still put a 4mil vapor barrier up on studs on inside and then install drywall? I dont want to create a moisture problem that does not exist.

thanks

[mannymanbo2]

to keep this answer short, you more then likely have a ventilated wall cavity. this type of wall is designed to allow interior moisture to pass through the wall board, through the siding to the exterior. Champion did this a lot in the 80's and 90's.
If you are going to wrap the home, you need to install a vapor barrier on the living side of the walls to keep moisture out of the wall cavity.