Waterproofing applications in buildings cause environmental impacts due to energy and resource consumption in the production and construction processes of materials. Considering tons of waterproofing materials are applied every year, it is clear that their possible environmental impacts besides physical, chemical, etc. performance characteristics of these materials should also be evaluated. In the article, the production and construction process environmental impacts of the waterproofing systems commonly applied to conventional and inverted flat roofs in Turkey are investigated by life cycle assessment method. The environmental impact analyses of the applications determined for conventional and inverted flat roofs are carried out with SimaPro simulation program, which analyzes life cycle of products and services. According to the results obtained; the total environmental impacts during the production and construction processes are the highest for the mechanically fastened PVC based waterproofing system in conventional flat roof while they are the lowest for the bitumen based liquid waterproofing system in the inverted flat roof. The research results will help architects and engineers preferring waterproofing applications with low environmental impact. Additionally, the paper will also be a guide for future studies where different applications to be carried out in other building subsystems will be investigated environmentally.