This paper presents an exergy-based sustainability analysis of manufacturing roof tiles from plastic waste in Uganda. This work focuses specifically on the developing country context and on utilizing waste material. A summary of the current Ugandan plastic waste situation, environmental and health issues associated with plastic waste, current means of recycling plastic waste into new products, and an analysis of the Ugandan roofing market is presented. The total exergy consumed to produce one batch of 75 tiles is over 240 MJ, the potentially recoverable exergy is nearly 17 MJ (8% of consumed exergy), and the realistic recoverable exergy is over 6.4 MJ (nearly 3% of consumed exergy). Recycling plastic waste into roof tiles saves a net 188 kg of CO2 from entering the atmosphere per batch when compared with open burning. If all of Kampala’s plastic waste was converted to roofing tiles, nearly 560 tonnes of CO2 could be saved per year.