I am planning to build a 10'(L) x 10'(W) x 8'(H) poured concrete foundation for an observatory. I have two questions that I hope to get comments on:
1. I am planning to pour a concrete slab roof on this foundation, which will serve as the base for my observatory (an old Sky Tent for now). Must I isolate the pier from this slab, or could I anchor the slab to the pier without introducing vibration issues?
2. Given that the pier will be approximately 10' tall, is a 12" diameter Sonotube (with rebar) adequate, or should I consider something larger? I guess this answer may depend on the answer to my first question.
Thank you for sharing your experience.