I'm redoing a small utility room in my 1950s house. After removing the drywall, I found 1.5" fiberglass insulation stapled between studs on the external wall. I'm tempted to tear it out and replace it with modern 3.5" insulation. A couple quick questions:
1. Is this a good idea?
2. Do I need to worry about a vapor barrier?
The house has wood siding and is located in Kansas City, so we see a wide range of climate.