FIRM-FILL® High Strength Floor Underlayment is the economical solution to correct concrete problems. It resurfaces any cracked or damaged concrete to better than new, providing surface hardness from 2500 to over 3800 psi. From feather edge to 3-1/2 inches in thickness, FIRM-FILL® High Strength Floor Underlayment provides a durable, flat floor for virtually any finished floor covering.

• Cracked or damaged concrete
• Pre-cast concrete
• Cast-in-place concrete

• Corrects cracked or damaged concrete, creating a new, flat surface
• Can be installed from feather edge to 3-1/2 inches in thickness
• FIRM-FILL® High Strength Floor Underlayment has compressive strengths from 2500 - 3800 psi
• Rapid installation; up to 40,000 square feet installed per day
• Quick drying; can be walked on in 90 minutes
• Expert application; installed only by trained, Licensed Applicators
• FIRM-FILL® High Strength Floor Underlayment has 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	7 psf at 3/4"	C-472
Thickness	Feather edge to 3 1/2" (89mm)
Compressive Strength	2500 - 3800 psi	C-472
Thermal Performance	K-value of 3.34 Btu; R-value of 0.30 ft2.h.°F/Btu	C-177-76
Fire Hazard Classification	Flamespread index 0; Fuel Contribution 0; Smoke Density 0	E-84
Patty Size	7 1/2" (203mm) plus or minus 1/2" (13mm) in diameter
Sand	1/8" (3mm) or less washed plaster, masonry sand or silica sand	E-11
UL listings	Listed in over 83 1, 2, 3 and 4 hour floor/ceiling assemblies