We need denser housing = low rise densification with roof terraces/gardens on impenetrable = never leak roofs with zero structural maintenance using stainless steel rebar = never corrode, but add only 2-3% to base costs. We have millions of structures failing after 30-50 years due to steel rebar corrosion. The construction industry is aware of this, but does not implement it by intent. With impending zero population growth looming in many areas, we need zero cost growth housing.