Modern roofing-singapore use high-tech materials like PU injection to stop leaks from the inside. This "negative side" waterproofing is useful when the exterior is difficult to access or when a quick fix is needed for a concrete crack. The polyurethane foam expands when it meets water, creating a tight seal within the structure. While not a permanent replacement for exterior repairs, ... https://kkroofspecialist.com.sg/roofing-singapore/