I need to add protrusions for various vents, disconnects, etc. in my renovation and I’m planning to use PVC mounting blocks cut from a plank of Azek.

I want to know if there is a minimally invasive approach to protecting the sheathing given that I eventually want to replace all existing Tyvek and siding. Lots of problems with water tightness and flashing particularly with my windows as I’m seeing rotted sheathing, not to mention I have to eventually replace bottom plates and sill plates which are rotted from decades of sitting concrete slab.

I know you’re supposed to overlap your Tyvek and flashing tape in such a way that water will bead down but I don’t see a practical way of doing that without removing damn near every piece of siding, which is nailed at both the bottom and the top of every plank by the way.…