The Expert Guide to Reinforced Bitumen Membranes (RBM): Superior Waterproofing for Singapore Properties In the tropical context of Singapore, where the afternoon sun can reach 34°C followed by an immediate torrential downpour, the structural integrity of your roof is under constant duress. For many landed properties and commercial buildings, the standard choice for "heavy-duty" protection is Reinforced Bitumen Membranes (RBM). At Gaushan Construction, we have seen that while many contractors offer bitumen roofing, few understand the nuances of the application required for our unique climate.