Packing (eliminated for 1 or 2 hr. Systems)
Listings with 3-M, Hilti, Rectorseal and Nelsons all require a minimum of 1 inch of mineral wool batt insulation, packed tightly, into both ends of the sleeve and recessed for the amount of sealant to be used. The wool batt acts as a backing for the intumescent sealant that is used to seal both ends of the sleeve. Mineral wool batt insulation is a common fireproof material used to insulate hot water heaters, fireplace inserts, and heating ducts. The best sources for this packing material are the local commercial insulators in your area. Note that some old-timers may call it rock wool. Our vertical and 4 hr. Systems do require this packing.
Intumescent Fill Material (putty)
All of our Sleeve Systems require the use of an intumescent caulk or putty to seal both ends of the sleeve. This material expands in the presence of heat/flame, suppressing the spread of a fire through the sleeve system penetration. The way a sleeve is packed and sealed is directly proportional to the amount of time a system will suppress a fire. For example, a 1 inch thickness of intumescent putty may be sufficient for a 1 or 2 hour rated penetration but a 3 or 4 hour application might require a 2 inch (or more) thickness in the ends of a sleeve system. Several fill material manufacturers have developed, tested, or engineered through penetration systems combining our sleeves and their fill material. All of our Firestop Systems have our UNIQUE intumescent putty included with the sleeve.