In our platform (Openland, W18) we have identified a LOT of buildings that can be built up in SF and current laws allows this. This is not high rises, but you can upgrade from 1 story to 3-4 stories easily. But why this buildings are still single story?

I suppose there are other problems like lengthy process of permitting (basically at least 1 year for issuing building permit) and entitlement (unpredictable). This huge delays reduces margins of a projects and in some cases they became unprofitable.