Pre-formed foam block maintains tight firestop seal to prevent fire, smoke and toxic gas transmission
Fits medium to large openings in wall and floor through-penetrations
No cure time means faster completion
Block is paintable with primer
Installation requires no special tools
Can be repaired and reused as needed, saving time and labor
Firestop tested in accordance with ASTM E 814/UL 1479
Can be sealed with 3M™ Fire Barrier Rated Foam FIP 1-Step and other 3M™ fire barrier sealants (sold separately)
3M™ Fire Barrier Block B258 is a pre-formed foam block designed for easy installation to effectively seal larger openings against smoke, toxic gas and flame. It is simple to use and helps reduce sound transmission.
A Better Way to Fill Large Gaps
When sealing larger cavities, use 3M™ Fire Barrier Block B258 (PDF, 78 Kb) to restore the integrity of the wall with a simple "stack, seal, and done" application, without the use of special tools. The blocks are engineered to remain securely in place, eliminating traditional wire mesh reinforcements. Pre-formed blocks help technicians fill large openings quickly (PDF, 252 Kb). The material is easy to trim on site without special tools, achieving a tight, custom fit. No cure time is required, which means installation is completed faster, and the blocks are paintable with primer for a more seamless appearance.
The blocks are fully re-enterable and reusable, saving time and money, while minimizing waste. Once the opening is filled, seal around the perimeter and any penetrating items with 3M™ Fire Barrier Rated Foam FIP 1-Step or other 3M™ fire barrier sealants (sold separately).