Surface Defects Underlay

(1)  Underlay beneath resilient or ceramic floors applied with an adhesive shall have all holes or open defects on the surface patched so that the defects will not be transmitted to the finished surface.

Article 9.30.2.5 Ontario Regulation 332/12 Building Code,   O. Reg. 332/12: BUILDING CODE (ontario.ca) © Queen’s Printer for Ontario, 2021