On Friday, May 16, 2014 11:33:48 PM UTC-5, wrote:
Hi, My attic has 2x6 joists. The (ancient) fiberglass insulation between the joists appears to be matted down to about 2" thick. Do I rip it out and replace with 6" thick batts and add more above that? Or do I leave it, add 4" batts, and add more above that? All opinions appreciated. Regards, Theodore.

Any bats added above the joists should be placed at right angles to the direction of the original bats to ensure there are no accidental "chimneys".