MOUNTING FOAM MR BUILD B1 is a one-component professional polyurethane foam with fire-fighting properties. Meets the most stringent technical requirements of DIN 4102 part 1 for building materials; class B1, where the fire resistance time reaches 240 minutes. An hour after polymerization, the foam can be cut, sawn and plastered, provided that the temperature regime for the cylinder and surface is observed from +5°C to +30°C, and ideally +20°C. (Foam tested to BS 476 part 22.