Insulation and vapour barrier work happens in a narrow window. Rough-in is complete — plumbing and electrical are in place and tested. Board is ready to go up. Insulation and barrier go in during this short window. Everything goes in, then immediately board closes it all in. None of it is visible again.
The narrowness of this window means work happens quickly. Insulation is placed, the barrier is installed and sealed. The work is inspected and verified. Then drywall goes up and the cavity is closed. The entire assembly — insulation, barrier, seals, and continuity — has to be right the first time because it is never visible again.
What is verified while visible, described as a sequence of checks rather than requirements, includes: insulation is in place and complete, barrier is continuous and laps are sealed, penetrations are sealed, and the assembly is confirmed as installed. These checks happen while the cavity is still open, before boarding closes everything in.
Re-instating what demolition took out is an easily forgotten line of scope. If existing insulation or barrier was removed during demo, it has to be replaced during this stage. If the scope was to maintain certain assemblies, they have to be put back. This is a clear scope item that sometimes gets overlooked.
Why nothing here is visible afterwards, and what that means for wanting to see it at the time, is straightforward: this work is never inspected visually after boarding. The only inspection happens while it is visible. This is why getting it right during this stage is critical. This ensures quality outcomes