Batts are available in different thicknesses
With the thicker batts offering a higher resistance to heat flow. This resistance is known as R-value, with common R-values for walls being R11 to R19, and R30 to R38 for ceilings.
An Alternative – Cellulose
When inhaled, particles can cause coughing, nosebleeds, and other respiratory ailments. Very fine airborne particles are capable of becoming deeply lodged in the lungs and are believed by many to cause cancer and other serious afflictions. OSHA considers this threat to be serious enough that it requires fiberglass insulation to carry a cancer warning label.