I live in a 80yr flat roof terrace house in Montreal. Rainwater drains from the roof into the sewer system through the house. In the last few years we seem to be getting monsoon like rain storms causing water to backup into the basement. The city does not allow for sewer backup valves because that would cause the rainwater to come through the walls wherever there is a joint in the rainwater pipe. Is there a way of changing the roof to redirect the water into rainbarrels in the backyard.