Insul Stick is also a castable restoration product but is more specifically used for parging over the firebrick in the smoke chamber or for exterior installations. It provides insulating value and strength, and can also be used to seal masonry wall penetrations. It can be cast, parged, or troweled and should be applied ¼” to ½” thick. You will need 2.5 lbs. per square foot when applied ½” thick. Insul Stick is packaged in 5 and 20 lb. pails.