3M Fire Barrier Moldable Putty

A one-part, ready-to-use, re-enterable, intumescent putty that can be easily formed to firestop through penetrations and blank openings in fire-rated assemblies. Often used to fill voids in large openings and/or complex firestop systems. Provides up to 4-hours of fire protection. Dark red moldable putty stick.


  • Firestop tested in accordance with AS1530.4 and ASTM E 814 (UL 1479)
  • Provides draft and cold smoke seal
  • Often used to fill voids in large and/or complex firestop systems
  • Pliable and conformable (molds easily into required shapes)
  • Helps reduce noise transfer (STC-Rating of 56 when tested in STC 56-rated wall assembly)
  • Noncorrosive to metal and compatible with synthetic cable jackets
  • Will not dry out or crumble, re-enterable