I am preparing to finish the space above my attached barn. It is framed with 2x4 studs, and wrapped with 1x3 strapping and sided with 1x10 rough cut shiplap barnboard.

My question lies in preparing the walls for insulation -

The shiplap lets air and moisture move through the seams, I want to seal this off before adding insulation. Should I use a tyvek type product between the studs, or cut sheets of sheathing to fir in between them?

I will be using R-19 Kraft faced insulation and then blueboard and plaster.

Please help - all suggestions welcome