My first question is about the depth to dig for the base. I've heard and read anything from 7" to 18". I live near Pittsburgh PA, so we get some pretty cold winters, and I was wondering if the base needs to be below the frost line. Also, we have a lot of clay, and not much topsoil. We also have a hill that will drain into our yard where the patio will be and was wondering if the amount of base stone and/or pea gravel will need to be greater because of this.

Another question is about building stone/paver stairs. I'm not sure the best way to design these. Are they typically built on top of the patio block/paver, meaning build the patio first then build the steps on top, or is it best to build the step base and steps first, then build the patio up to the stairs? Also, if anyone can point me to a good resource for building the steps, I'd appreciate it. The only decent one I found was from Allen Block, but it was more a promo video than an actual step by step.

Thanks to anyone for responses, I'm sure I'll have a lot more questions as I design and build the patio.