Tools and Supplies

Bobcat
Laser level
gravel
foundation forms - 2x10 lumber
rebar
rebar wire
Drill with 1/8" bit
Concrete - calling in a cement truck or get bags of concrete mix + cement mixer + water
Cement mixer, water hose, buckets for carrying concrete
2x4 wood scree boards, 2' long
Measuring tape
wood forms
[40] wood stakes for fastening the foundation
3" screws
[16] 1/2" rebar stakes, 2.5' long
Sill plate gasket (above foundation, below sill plate)
String

Procedure

Level and clear the site with a bobcat or bulldozer.
Grade the site such that the house is on a pad with drainage moving away from the house
Use a laser level or string level so that the elevation is equal throughout the footprint of the house to +/- 1"
Spread a truck load of gravel for the foundation so that it is 6" thick
Mark the 4 corners of the house at 16'1" (to accommodate 1/4" space between panels), roughly, such that the front of the house faces south
Adjust the 4 corners by declaring one side as fixed, then moving out the 16'1" length. Use string to fix the length at 16'1". Also use a string to connect the 2 adjusted corners, at 16'1"
Measure the diagonals. If they are not equal, shift the 2 adjusting corners, maintaining the 16'1" distance between all sides
Make sure the diagonals are equal +/- 1/4"
This now marks the outer edge of the foundation.