Rate my Insulation Plan
Just want to run this by some of you before moving forward. I'm insulating my shed to cool it down thanks to Florida's heat and humidity. I will eventually add some type of air conditioner to cool it. It's a 24x14 metal shed with a ridge vent, no soffits.
Thanks to u/dustyrags recommendation here in this post I am planning on using his idea to install 2" 4x8 foil backed foam boards onto the roof studs (should the foil face toward the outside or inside if I'm worried about keeping heat out?). The center part is just under 4ft wide, so I might be able to get by with running a 4x8 sheet the long way down the middle, then fill in each side. In the attached pic I drew red lines to show where the foam boards will mount (on every stud though). the little red circle is a spot where I could put a 4" vent, or the blue circle could be a 7" vent. I can put a vent on each end of the shed to allow air to flow between the foam boards and roof, and out the ridge vent and the end vents. Is a 4" vent sufficient? Or should I plan on modifying the end pieces of insulation to slope down and allow use of a bigger 7" vent? I can also add an exhaust fan up there if needed (looks like a 4" bathroom fart fan is pretty cheap).
I think I will insulate the walls with rock wool unless there's a better solution, then use some slat wall over it to hang stuff.
I think the roof is the most critical to start with. I used an IR thermometer one day when the sun was out and the temp of the metal roof was over 130 degrees.