I have worked a bit with AZEK and some of the other PVC materials since I built my wood cupola some time ago. If I built it again, that's what I would use for the exposed "wood" surfaces. It would be built over some kind of structural frame probably made from PTL. PVC trim materials are not too good structurally. Another shortcoming is that they have some limitations as to what color they can be. If you like white, you're in business. If you want a darker color, not so much. They don't like getting hot so you haver to be careful about the color or it'll over heat. AFA the hysterical commission, PVC would appear exactly as a similar wooden structure especially if you paint it which may seem to contravene the primary reason for using it, but the stuff I used for my porch balustrade was WHITE!! and I painted it with a bit tamer shade of white. Used Sherman Williams "Super Paint" over a lightly sanded surface and it is doing fine after seven years. Filled the screw holes with Bondo which was another reason for the paint. It also helped with the cut edges of the PVC. Yes, there are special matching caulks and stuff, but that's what I wanted to do.
