Thanks for all the links. I’ll have Hubby take a look. My dream is to have a big sun room added to the house, so that I can go out the patio door and into this huge room.
About 3/4 devoted to plants and the other quarter to a nice hot tub. LOL
A wood frame covered with glass or multi-wall polycarbonate glazing would be great for a sun room. Greenhouse vents or other automatic venting might also be added, if sunny days contribute too much. FPSF (frost-protected shallow foundations) are also good to look into for many kinds of projects when budgets allow (thermal mass). Even gravel areas can be surrounded by supported (maybe with treated wood) board insulation.