Insulating flat roof with exposed rafters

rblevow

I have a 1950's home in Palm Beach County, FL. In an enclosed area that was once a screened porch and Florida room, the roof is 1x6 tongue and groove on 4x6 rafters spaced 24" oc. That is the interior ceiling; no insulation. The area is air conditioned but obviously it gets very hot in the summer. I would like to install insulation in a way that leaves the bottoms of the rafters exposed. One thought is to install 4" EPS block (~R-30) between the rafters with thermoplastic decorative tile below supported by inside corner molding. I've read a number of posts that talk about venting insulated ceilings and wonder if such an unvented installation would be workable. In any case, venting the rafters would be very difficult as one area is an interior room.

I would appreciate any comments indicating whether my idea is workable or not and any suggestions for alternatives, particularly ones that do not require installing a new ceiling on the rafters.

bluebird5

well a picture would be nice but from what im getting, you have got 2 ways to insulate. put insulation on the inside and fur the beams down to keep them exposed or take the roof off and insulate form the outside with foam sheets and leave the inside alone. just my 2 cents