D u r a – C a p ® F l o o r Underlayment (commonly known as “Gypcrete”) is a nonstructural gypsum concrete used with aggregates in pouring crack resistant, fire resistant and sound-insulating floors. Batch mixed on the job, barrel mixed or pumped into place by authorized applicators, it is ideal over veneer and non-veneer wood subfloor panels, precast concrete and cast-in-place concrete. With proper preparation, Dura-Cap® Floor Underlayment (Gypcrete) can accept virtually any type of flooring material.