Designing Kitchens and Bathrooms - Batchtub wall reno

I recently took apart my bathroom walls the tile was loose and drywall soggy. They had built out a 2x4 wall to avoid some piping but i was able to redirect the pipe to get back the origional wall. I took off the origional drywall (origional wall not soggy) reinsulated , vapour barriered put old drywall back up to gain depth to the window new 1/2 on top of old and will be installing 5 piece plastic surround. My question is will i get condensation behind the surround, large wall is exterior wall. I ripped up a shower at work today and the 2 layers of 1/2 drywall were mush and could be punctured with a finger i would like to avoid this with mine.

If i put strapping up for it to breath where would it go?

between the first layer of drywall or second


sorry about the long story

i think the bigger problem is the vapor barrier if the drywall is primed and sealed and then caulk the surround in good at bottom and top then u should be ok most 5 pc surrounds are gonna leak eventually its just how long u let it go as far as severity of damage

You've got the vapor barrier under the drywall correct, so you should be good to go. I'd prime the drywall behind the surround prior to installation. Do a good caulk job at all seams & especially the top & bottom & be sure to replace the caulking occassionally as needed & the shower should outlast you.