There really is just a severe lack of building science education in American construction, because the margins are so thin and it is still dominated by blue collar "man in a van" companies. So you have boneheaded contractors drilling holes into air barriers because that's how it's always been done.

Heat conduction through studs in an insulated wall also carries sound. A 2x6 plate wall with 2x4 studs on alternating faces (think slalom) helps with both.

Fortunately this was part of a project to finish my home office, so I still had access to the space between the internal and external walls. Not only could I see the insulation damage, I could also repair it without too much effort.

But in general, I agree there's a responsibility gap when it comes to these installers. I think the best practical solution for now is to factor into such projects the cost of restoring a building's thermal envelope.

EDIT: I should mention that a blower-door test might not have detected this damage. The cavity whose insulation was damaged has pretty good draft-blockage from the rest of the house, due to fire-code requirements.

What, $5 for a tube of exterior grade caulk? Vapor barrier seal tape is 10 cents a foot. Add in $10 in labor per penetration and you're done.

You could leave it out of your estimate entirely and not even notice if your guys did the work.

edit: I'm a commericial construction estimator

I agree that restoring an air seal is trivial on a per-hole basis. My main point was restoring the lost insulation performance that comes from trashing one stud cavity of fiberglass batt insulation when the hole is made.

Based on my limited knowledge, I don't know what impact that might have on the overall structure's thermal efficiency. I would also worry about risk to any water-carrying pipes running through such a section in a cold climate.

In the Midwest there is an utter catastrophe where modern high efficiency houses are rotting away because construction and design errors let water in or water to condense with no way out.