With a continous run ridgevent as well as continous run eave venting, you can run radiant barrier on the underside of the rafters. The airspace between the roof sheating and radiant barrier is stopped by the radiant barrier. The heated/trapped air is directed up and out the ridgeventing. No other insulation type would be necessary in the rafter spaces , as you mentioned, would block airflow. If you want some form of insulation in there, you could install 1-1/2' foam board panels inbetween the rafter spaces keeping it down at the lower part of the rafters and keeping a 2' airspace between the roof sheathing and the foam board, but dependent on your location, imo, you wouldn't need it. You will also want to remove or disable the rotating vent that is on the roof. Below is a link to radiant barrier rolls and you can cover the underside of the rafters after the radiant install with drywall, tongue & groove materials, or any lid covering that you have planned on without losing any effect of the radiant barrier. This method works great in attics as well to keep attics cooler as long as you have the continous run ridge and continous run soffit/eave venting. Below is only as an example, you can check your local suppliers. The rolls I use are 50' wide by 1000', have a kraft paper backing on one side, the foil facing on the opposite, with a fiberglass mesh inbetween for strength, and is non- perforated. You will want to foil tape all seams as well as any rips or tears before covering over with your ceiling material of choice. Here is a link that might be useful: radiant barrier

Rooms above unconditioned spaces are always hard to conditon. I usually recommend foam (and no, Gary don't care to go there...not a foam person in most cases!) in these applications. Usually my foam recommendation is for existing homes on piers with no working room to do the following install. If you install batt insulation, use unfaced batts and oversize the batt. instead of R30, install R-38 to keep insulation in full contact with the flooring to avoid any future condensation issues as the batt settles. Use a foam sheathing board to the bottom of the floor joists and finish porch ceiling as planned. Cost will be less than foam insulation, insulation value will be achieved and the foam sheathing boards will stop any air flow through the insulation that would lessen the R-value of the batts. Same performance as foam insulation. In my area people complain of these and bonus rooms over garages staying hot (hot humid climate here with 9 month cooling season!). Insulation isn't enough - air flow has to be stopped before these rooms can be comfortable. Unfortunately many a/c companies will oversize systems to try to achieve this, at a higher install and operating cost to the homeowner..and usually it doesn't work. Oversizing can lead to many issues. Best of luck to you! Hello Manhatten42..how have you been? Is vapor barrier location ok for my suggestion? And folks if you don't know Manhatten42..he is a great resource, excellent code specific info.

Caroline I don't live in Rapid City. I live N of Pierre. Its even closer than you think. Someone mentioned a humidifier. I can tell you right now it makes a huge difference. My DH keeps telling me, he can't believe how much warmer it feels in the house when it is on. I think it is the moisture that makes it feel warmer. I can tell the difference right away. The minute I turn the heat on in the fall I start the humidifier. I used to have two of the gallon ones going at the same time. A few years ago I went to a yard sale and someone had one of the console ones. I think I paid about 5 dollars for it. for it. It runs all the time now. Every night I have to fill at least one of the 3 gallon tanks but it is worth it to me. WE have our thermostat on 57 at night and after I come home from work we turn it up but only about to 65

You say 'combine' the porch with the kitchen. Meaning one room or simply another room with an open doorway? 1" is not enough space for insulation and may not be enough space for most floor heating systems. It may be enough for an electric system, but the operational costs for an electric system would be high. I was thinking more on the lines of a heated water system. Having a height difference of less than a couple inshes in the same room is not usually a good idea, creates a huge trip hazard, even with sloped transitions between the two levels.