What type of insulation can be used near knob and tube wiring?
None. K&amp;T was designed to have an air space around the wires. If you fill that space up with insulation--any kind of insulation--you're defeating that part of the design and causing a major fire hazard. Keshlam is right--the best solutions is to bite the bullet and have the house re-wired. Then you can install whatever kind of insulation you'd like, including in the walls, which right now are most likely empty and uninsulated--another consequence of K&amp;T wiring.