Pier & Beam Foundation for Tiny Home

[homesteadhappy]

I'm new to the terminology, so please bear with me.

Including the porch on two sides of the house, my total dimensions are 24'x24'. The house itself is 16x20. I am planning on a pier and beam foundation. The county I am in is completely unrestricted (no building codes/zones/permits/building department/etc). There's not a single red light in the whole county and much of the population is Plain (Amish/Mennonite), just to give context.

Frost line is 10-12" and state code says we should have a minimum 12" deep footing for the piers. I was going to go 24" down, 6" compact gravel of some kind, and then 18" Sonotube cement footing. I was planning on doing double 2x8 beams (aka 4x8 beams) and doing 2x8 joists every 16" oc.

I am trying to figure out how many piers I need. I was thinking about doing 4 rows of 4 (16 total distributed evenly), 4 rows of 5, or 5 rows of 5.


Am I wildly off here or is this okay? Thank you!