Remdeling project is requiring 5/8 firecode sheetrock to be installed in garage entry to house. Installation not the issue. Entry room will have firecode sheetrock on outer wall (which is inside the attached garage) with standard fiberglass batt insulation inside 2x4 stud wall, and 3/8 sheetrock on the inner walls of the new area. The new Area is essentially a small "mudroom" entry off the kitchen.
Question: since 5/8 sheetrock (for the fire-code wall sides) is so cumbersome to handle, is it reasonable to use double 3/8 thickness sheetrock, which gives 3/4 inch total protection and is much easier to handle?