Unvented 3rd floor attic space
Having gotten married last year, I'm moving to her city, and building a new home ( at 68, I think I've got one more build left in me ). The house is in St. Augustine, Fl., about 1 1/2 blocks from the bay and maybe 1/3 mile from where bay joins the ocean. Plan I designed ( and wife's request ) calls for a 3rd floor room, about 14x17 over her office on second floor. It has windows on all walls, and she thinks she will be able to watch the bay and Atlantic, while relaxing and reading. In talking with the insulator and a rep at Grace, what I want to do is make it an unvented roof ( roof area of 1st floor and 2nd floor will be std. vented roof ). Current plan calls for 5 1/2" of foam applied to under side of sheathing, with full covering of Grace water and ice HT ( high temp. ),so I don't have to worry about any leakage, and metal roof. Like I mentioned it 14x17, and with a 4/12 pitch hip roof.
Venting and insulation of roofing is not my main specialty, and I would like to get some input and thoughts from guys who deal with this .
The main idea is to be smarter than a piece of wood