T2960

SpecSeal SIL Silicone Firestop Sealant | Class 1 W Ratings

One-part, neutral-cure silicone firestop sealant for sealing openings in walls and floors to control the spread of fire, smoke, toxic gases, and water during fire conditions.

Available in non-sag (SIL300) and self-leveling (SIL300SL) grades with excellent water resistance, UV/ozone stability, and Class 1 W Ratings (UL1479).
Tested to ASTM E814 (UL1479), ASTM E1966 (UL2079), CAN/ULC-S115 — ratings up to 4 hours in tested systems.

silicone firestop sealant
UL1479 firestop
UL2079 joint firestop
CAN/ULC-S115
Class 1 W rating
neutral cure
low modulus
non-sag & self-leveling

Key Features & Benefits

  • Neutral-cure silicone; adheres to most substrates without primer
  • Low modulus for dynamic joints; excellent recovery after movement
  • Class 1 W Ratings (UL1479) for water-tight sealing where required
  • Excellent water resistance, UV and ozone resistance for long service life
  • Superior smoke seal and chemical resistance; suitable for polluted/corrosive atmospheres
  • Auto-bonding — new sealant adheres to cured sealant to simplify repairs
  • Non-halogenated; no asbestos, no PCBs; LEED v3/v4/v4.1 low-emitting materials credit eligible
  • Meets ASTM C920 (SIL300: Type S, Grade NS, Class 50; SIL300SL: Type S, Grade P, Class 25)

Applications

  • Through-penetration firestop systems and joint systems
  • Non-combustible penetrants; electrical/data/telecom cables
  • Construction gaps, expansion joints, perimeter/curtain wall safing, and top-of-wall joints
  • Vertical and horizontal joints between metals, masonry, concrete, and common substrates

Physical Properties — As Supplied

Property SIL300 (Non-Sag) SIL300SL (Self-Leveling)
Consistency Trowelable Pourable
Density / Weight per Gallon 11.6 lb/gal 11.5 lb/gal
Solids by Weight 100% 85%
Viscosity 1,200,000 cps 25,000 cps
Application Temperature 35°F (-37°C) to 140°F (60°C) 35°F (-37°C) to 140°F (60°C)
Storage Temperature ≤ 80°F (27°C) ≤ 80°F (27°C)
VOC Content 20 g/L < 47 g/L
Shelf Life (from manufacture) 18 months 18 months
Tooling Time 25–30 minutes 25–30 minutes
Tack Free (ASTM C679, 77°F/50%RH) 3–4 hours 50–60 minutes
Sag/Slump (ASTM D2202) 0.1” max N/A
Storage Warranty Period 12 months from shipment in unopened container at ≤ 80°F (27°C)

Physical Properties — Cured

Property SIL300 (Non-Sag) SIL300SL (Self-Leveling)
Color Concrete (limestone) Gray
Flame Spread / Smoke (ASTM E84) 5 / 45 5 / 45
Mold & Fungus (ASTM G21) 0 1
Movement Capability ±50% (ASTM C719); ±35% (ASTM E1399) ±50% (ASTM C719); ±15% (ASTM E1399)
In-Service Temperature -35°F (-37°C) to 350°F (177°C) -35