Tongue & groove insulation - Dynamic Composite TechnologiesStyrofoam SMTG XPS rigid board distributed by DCTech is designed to be used as thermal insulation in walls, floors, and roofing applications. Styrofoam insulation is an extruded polystyrene (XPS) blue board with a closed cell structure which means it won't absorb moisture. The Styrofoam SMTG boards are designed with a tongue and grooved edge to ensure the boards lock together to prevent moisture passing through the joints where the tongue edge is up and the groove ...