Mapei Ultraflex 1 Mortar Gray Polymer 50 lb

This is Ultraflex 1 Mortar Gray Polymer, a polymer-modified thin-set mortar meeting ANSI A118.4E and A118.11, ISO 13007 C2E. A 50 lb bag gets you 75 to 90 sq ft with a 1/4" x 1/4" square-notch. Step up to a 1/4" x 3/8" square-notch and it drops to 55 to 65 sq ft, which is why the notch matters more than the bag count. You get 30 minutes of open time. Pot life is over 2 hours. Keep traffic off for 24 hours and heavy traffic off for 7 days. Grout after 16 to 24 hours. It is approved over cured concrete, masonry, cement board, mortar beds, and exterior-grade plywood on interior residential floors. Keep it off hardwood, OSB, metal, moisture-sensitive stone, resin-backed tile, and anything under permanent water. For exterior commercial walls Mapei points you at a different system, so check the job before you buy this for one. Both the Mississauga and Barrie stores carry it.