The original FIRM-FILL® Gypsum Concrete floor underlayment is designed for use in multi-family housing to satisfy acoustical ratings and fire codes. With excellent STC and IIC ratings as well as over 83 UL listings, FIRM-FILL® Gypsum Concrete floor underlayment is an excellent choice for jobs needing compressive strengths up to 2000 psi.

• Condominiums
• Apartment Buildings
• Townhomes

• Flattens subfloors
• Provides excellent STC (sound transmission) and IIC (impact isolation) ratings
• Possesses over 83 UL listings
• Lightweight and crack resistant
• Easily installed; over 40,000 square feet can be installed per day
• Quick drying; can be walked on in 90 minutes
• Expert application; installed only by trained, Licensed Applicators
• Approvals from ICC-ES and HUD
• Meets ASTM F2419, Standard Practice for the Installation of Thick Poured Gypsum Concrete Underlayments and the Preparation of the Surface to Receive Resilient Flooring

Technical Data	Properties	ASTM
Weight	6.5 psf at 3/4"	C-472
Thickness	3/4" (19mm) (minimum over wood) to 3 1/2" (89mm)
Compressive Strength	1200 - 2000 psi	C-472
Thermal Performance	K-value of 2.45 Btu; R-value of 0.41 ft2.h.°F/Btu	C-177-76
Fire Hazard Classification	Flamespread index 0; Fuel Contribution 0; Smoke Density 0	E-84
Patty Size	8" (203mm) plus or minus 1/2" (13mm) in diameter
Sand	1/8" (3mm) or less washed plaster or masonry sand	E-11
UL listings	Listed in over 83 1, 2, 3 and 4 hour floor/ceiling assemblies