Fiberglass Insulation incorrectly installed in home

[SIM]

Fiberglass insulation is sometimes installed by stapling to the inside of the framing stud, instead of by stapling onto the stud face. The problem with installing and attaching fiberglass insulation to the inside of the stud is that it compresses the fiberglass insulation near the wall stud on both sides. This creates a double problem with respect to insulation or R-value.

First, when fiberglass insulation is attached in this fashion the entire stiud cavity is not insulated. A small gab of air space, about 1/2 to 1 inch, will be created along each stud. Realize that even a 1/2 inch gap is about 15% of the available space left uninsulated.

Second, when fiberglass is compressed to less than the 3.5 inch depth it is designed to fill, its insulating, or R-value is greatly reduced. The R-value probably drops to about 2.0 (from 3.2) at this very critical space alongside the wall stud.

[WashingtonState]

We see this all the time and it just amazes me that some builders still install fiberglass batts this way. One builder even pointed out to me that the fiberglass manufacturer still describes this method as a proper way to install. Just shows how out of touch the fiberglass insulation industry is with modern building science.