Urban fire response remains largely ground-based, yet the role of building rooftops as distributed UAV infrastructure remains unclear. Here, we develop a spatial planning framework that screens rooftops, models demand-weighted coverage and compares alternative deployment algorithms for Greater London. The framework combines building attributes, fire station proximity, an airspace exclusion layer and nighttime light demand weights. We evaluate NSGA-II, SPEA2, MOEA/D and a greedy baseline and select a representative layout from the observed trade-off between coverage and deployment scale. The selected 14-rooftop layout covers 83.78% of the demand weight reachable from the candidate set. When assessed against historical fire records, the rooftop network complements ground services under independently specified UAV and ground-service spatial scenarios, and their combined modeled coverage reaches 92.00%. These findings provide a case-specific planning reference for evaluating rooftop emergency infrastructure in other dense cities after local data, regulatory and operational adaptation.