<p>Extreme weather events have become more frequent in Rio Grande do Sul, with a climate disaster that affected more than 96% of the state's municipalities being recorded in 2024. In this event, one of the main problems observed was the absence of a management plan for construction and demolition waste (CDW) from the affected buildings, with its disposal being carried out inadequately. The Rio dos Sinos Hydrographic Basin (BHRS), one of the most affected, has conflicts over land use and occupation, resulting in large urban areas being susceptible to flooding. Considering this problem and the proposal of the model of buildings as material banks to reduce the impacts of the volume of CDW on floods, the objective of the article is to estimate the stock of materials present in the building stock of regions susceptible to flooding, using as a study area the municipality of Novo Hamburgo-RS, located in the BHRS. To this end, the methodology combined calculation models reported in the literature, a georeferenced building database, and studies estimating flood-susceptible areas. The results indicate that 22,767 buildings are located in flood-prone zones, corresponding to 2,317,000 m² of built area and an estimated 1,599,000 tons of concrete. These figures highlight the limited feasibility of large-scale relocation, underscoring the need to revise urban planning strategies and implement structural measures to reduce flood impacts and enhance resilience to future disasters.</p>