How much value is added to a property when permits are approved?

[Tom Munro]

Question - I'm looking for opinions on how much a property increases in value when all the permitting process has been completed?  

Background - I've recently moved across the country so instead of building this project for myself to hold long term (which was the original plan), I'm contemplating getting through all the permit approvals, and then selling the property as a ready to build package. 

I have a single family rental property on nearly an acre, locating in a rapidly growing community in NW WA. I'm in the process of applying for permits in order to convert it from a SFR into a commercial property. The plans are for a mini storage facility (3 buildings totaling 11,000 Sq ft) along with an 1,800 sq ft retail space. Cost to build the facility will be about $1.4 million including permit costs. For this type of development in my area, the permitting process is fairly extensive and costly (roughly $50,000 before the cost of the permits). Based on local prices, our estimates are that this property will generate around $16,500 in gross monthly revenue once its developed and fully rented. Making the value of the property roughly $2.5 million.

$16,500 monthly revenue minus 30% for expenses x 12 months = $138,600 annual net revenue. CAP rates in the area are roughly 5.5% so, we're looking at $138,600/0.055 = $2,520,000

As a residential property, Zillow/Redfin estimate that it's about a $510,000 value.  Obviously, once we're through the permitting stage and have all of our approvals, then most of the risk has been mitigated.  My question is how much does that increase the value of the property?  

Thank you for any feedback!