Learning how deep to dig footings below frost line level is critically important
Finding out how deep to dig footings below frost line levels will help you prepare for building your home foundation, but it will also help you stay within the local building codes. If frost gets under the concrete foundation, it can push it up and make the concrete buckle. We've all seen how highways have frost heaves that make them wavy to the point where they need to repaired. You don't want that to happen to your home foundation.
Your local building inspector will have the frost layer information you will need to plan your foundation. This varies wildly depending on location because it's all about altitude. The local codes will tell you how far down you need to dig to get well beneath that layer where the ground freezes. It will also instruct you on the rebar schedules that will be inside the footer and foundation wall.
