Bostik's EFA+ Elastomeric Wood Flooring Adhesive 5 Gallon EFA+ Elastomeric Flooring Adhesive is a one-part, trowel applied, moisture-cure urethane adhesive; this advanced, scientifically-formulated adhesive does NOT contain any water. Once cured, EFA+ is waterproof and is not adversely affected by exposure to moisture or water; its superior properties provide a tough, flexible, tenacious bond to a variety of surfaces. EFA+'s elastomeric characteristics allow the adhesive to move with the wood as it expands and contracts over the life of the floor. EFA+ may be used to adhere all dimensionally stable engineered, acrylic impregnated, solid plank-flat milled, shorts, bamboo and parquet hardwood flooring designed and recommended in writing by the hardwood flooring manufacturer for glue-down applications. This adhesive can also be used to install plywood as described, as well as ceramic tile, marble, and stone inlays for light commercial and/or residential applications. EFA+ may be used over all properly prepared substrates common to hardwood flooring installations, including: concrete, plywood, particle or chip board (underlayment grade), well-bonded vinyl and ceramic tile, cement backer board, gypsum patch/underlayments (dry, abovegrade), cement patch/underlayments, radiant-heat flooring, and terrazzo.