I used Redwood on my deck with wolmanized pine framing. We recently repaired a lot of the redwood that had gone away and the new material is not as good as it was 25 years ago. I probably would use some sort of plastic composite now with the treated framing.a

Sitting precast foundations on the top of the ground may be fine in AZ but would not work where there is freezing temps. We have to sink about 3 to 4' to reach stable levels for foundations here.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.