Remodeling bathroom - Insulation question

I live in NY (just to give reference with weather) and the house is 1985 construction (we just bought it last year).

We are renovating our basement bathroom over the next few weeks. 2 of the 4 walls are exterior facing.

I was told by a co-worker that when I rip out the existing sheetrock, I should look into the polyiso boards for insulation. Just cut them to fit between studs and glue. Seemed easy enough. However, I'm doing my research and am reading that polyiso is really meant to be a continuous line. I really cannot do this becuase the room is already framed and is small enough as it is. I cannot really lose 3-6" of space per wall.

Once we are done with the bathroom, we plan to move to renovating our finished basement. Let's just say the previous couple LOVED wood paneling! . So I'm looking at the bathroom being a "test-bed" for when we do the rest of the basement. With the basement, I do plan to insulate the ceiling as well for sound-proofing. The basement is our "theater room", so I want to do whatever I can to increase the sound proofing in the room. Right now, there is none.

With that said, is rigid foam still my best best? Cut-to-fit? Or should I do something like rock/fiberglass batting.

I am also 100% against spray foam. It is too permanent for my taste. If I ever need to run new wiring or replace existing, spray foam makes that a royal PITA.

Any input is appreciated!

Thanks!

Submitted March 03, 2015 at 07:45PM by Jnick96 http://ift.tt/1DErhJ3