A gradual increase in earth’s temperature is becoming a reality faced nowadays. Communities in informal settlements or deprived neighbourhoods living in buildings of poor quality are the most vulnerable to indoor heat stresses. Six test cubes were constructed on the rooftop of a residential building in Cairo, Egypt. Ten different thermal roof insulation ideas were tested and experimented in an urban living lab setting under real climate conditions. The 10 solutions were tested during peak summer hours and their efficiency was monitored along two consequent time intervals, where 5 solutions were monitored at a time. The two best solutions were tested again in winter. This experimental study showed that using reed mats and reed crate with wet burlap can reduce temperatures up to 3.5 degrees compared to conventional roof construction methods. The feasibility of the proposed solutions, their cost efficiency and their maintenance were discussed. We hope this experimental study can be scaled up to help vulnerable groups in informal or deprived areas to reduce their level of suffering from indoor heat stress. Low-tech and low-cost roof insulation can offer adequate thermal comfort for marginalized populations.