6", 6T-JS, Firestop Joist Shield, Required To Assure Ample Fire Protection When The Chimney Passes Through An Intermediate Floor, An Intermediate Floor Is 1 That Does Not Include The Location Of The Appliance Nor An Open Attic, A Typical Application Where A Firestop Joist Shield Should Be Used Is Where The Appliance Is Installed In The Basement Of A 2 Story House, As An Example With The Appliance Installed In The Basement, Firestop Joist Shield Should Be Installed Between The First & Second Floors.