There is a LOT more than zoning that goes into the cost of construction driven by regulations. I wouldn't be particularly surprised if you could only attribute

There is a LOT more than zoning that goes into the cost of construction driven by regulations. I wouldn't be particularly surprised if you could only attribute a single digit percentage of the all in cost to zoning for construction in the bay area. Here is how you could do a first order approximation: Find property zoned so you could build dense housing and get its cost minus the cost of the improvements. Then find matched property zoned for a single family homes, minus their improvements. The difference is attributable to zoning for the purpose of this approximation. What percent of that is that in the overall cost of the multi-unit construction? I'm not sure of the figure but given that the entire land cost isn't that big a percentage in dense construction, I expect the impact from zoning to be fairly small but not negligible.