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STI LC Endothermic Firestop Sealant

Availability: In stock

SpecSeal LC Endothermic Sealant is a latex-based gun grade firestop sealant for construction joints and non-combustible penetrations. After application, LC Sealant cures to form a flexible seal against the propagation of fire. Under fire exposure, LC absorbs heat and release water vapor resisting the progress of smoke and flame.

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Product Description


  • Installer Friendly, easily applied with standard caulking gun
  • Can be troweled on for larger applications
  • Tested for up to 4 Hours of fire resistance when tested to ASTM E1966/UL2079, ASTM E814/UL1479, and CAN/ULC-S115
  • Listed in over 80 UL Tested Firestop Systems!

Application Properties
Blank Opening Autobonding
Bottom of Wall Joint Movement
Cables Low VOC
Duct Permanent
Floor to Floor Smoke Barrier
Floor to Wall STC Rating
Head of Wall Water Based
Metal Pipe  
Wall to Wall  



Property Value
Colour Deep Red
Density/Weight per Gallon 10.7 lb/gal (1.28 kg/L)
Solids Content by Weight 81%
Solids Content by Volume 75.2%
Flame Spread 0**
Smoke Development 10**
Mold & Fungus Growth Rating (ASTM G21) 0
Movement Capabilities ± 12.5% or 25% in compression only****
Coverage For more information on product coverage see the following documents for Linear Joint & Penetration
pH 7.4 to 8.4
In Service Temperature Less than 185°F (85°C)
Storage Temperature 40°F (4°C) to 95°F (35°C)
Application Temperature 35°F (2°C) to 100°F (38°C)
STC Rating (ASTM E90-04/ASTM C919) 61 (Relates to Specific Construction)
VOC Content 57 g/L******
Average Volume Shrinkage (ASTM C1241) 21.5%
Shelf Life From Date of Manufacture 24 months
  • *Tested to ASTM E84 (UL723) at 14% surface coverage (modified test for sealants and caulks)
  • **500 Cycles per UL2079, AC30 (ICBO) and ASTM E1399
  • ***Per SCAQMD Rule 1168 (EPA Method 24)

Ordering Information

Catalogue Number Description (UOM) Qty. Case Qty. Weight (Each)
STI_LC120 20 Oz. Sausage - 36 cu in (592 ml) 1 1 1.70 lbs (0.77 kg)
STI_LC129 29 Oz. Tube - 52 cu in (858 ml) 1 12 2.56 lbs (1.16 kg)
STI_LC150 10.1 Oz. Tube - 18.2 cu in (300 ml) 1 12 0.96 lbs (0.44 kg)
STI_LC155 5 Gallon Pail - 1,155 cu in (19 liters) 1 1 55.81 lbs (25.31 kg)