A wave of upzoning across the San Francisco Peninsula is cracking open some of the region’s most supply‑starved housing markets, prompting multifamily developers to target obsolete office sites in Sunnyvale, San Mateo and Menlo Park for hundreds of new apartment units. Cities up and down the Highway 101 corridor are under pressure from the state to meet aggressive Housing Element requirements, and the combination of rising demand, favorable zoning and a shrinking pool of viable office stock is accelerating a new class of demolition‑to‑multifamily projects. “Rents have appreciated significantly, and with limited new construction starts, we’re anticipating rent growth to continue,” said...