We have a 1,000 SF house with a VENTED (luckily) flat roof in the Bay Area. We obviously. have a lot of humidity and fog here. We would like to retroactively insulate our flat roof but are concerned about moisture problems.

What is the best insulation solution for us? 

I’ve heard about installing foam boards over the roofing. I’ve also heard about “dense pack cellulose” between the roof deck and the ceiling drywall. 

Can we “dense pack cellulose insulation” by drilling holes in the side of the roof overhang and blowing insulation into it? (We would hire an expert.) 

I’ve read somewhere that dense packed cellulose allows moisture to “move” to the vented portion of the roof, thereby eliminating any moisture condensation problems. Is this true? 

Can we “dense pack cellulose” in a space that has a ceiling light (it’s not a can light). Can we dense pack cellulose in a space that has a ceiling fan? 

Thank you!