Hi everyone, we are replacing the wood siding on an older home with vinyl. In the process I want to add insulation from the outside, since the home likely has very poor insulation. I plan to tear off the wood siding, add fiberglass batt insulation, nail 4x8 OSB to the studs, housewrap and then vinyl. My question: do I need to put on vapour barrier as a first step? This would be awkward since it would have to go over the studs. Doing anything from inside is not practical since it is all lathe and plaster. Any ideas, tips?