You’ve heard of firestopping caulk and foam, but… pillows? Yes, you read that correctly. Pillows. Namely 3M™ Fire Barrier Pillows, little bundles of intumescent material that can be used to fill in and firestop larger wall penetrations, like the ones you get when you run exceptionally large cable trays from one room to the next. These are what you turn to when gaps are so big that soft materials like foam and caulk just don’t have the structural integrity to do the job – as a matter of fact, they’re UL listed to firestop openings up to 540 square inches.
Installing 3M™ Fire Barrier Pillows is a no-mess project – just fit enough into the gap to completely close it , and you’re done. Unless gaps that are too small to be filled by the smallest size pillow remain, there’s no need for caulk, putty, or other conformable firestop products. Fire Barrier pillows have a 3-hour flame rating, and they’re super easy to replace after a fire – there’s no need to scrape charred material out if the penetration gap. Just pull out the spent pillows and pop in new ones whenever you need to.