4 ms·

I'm still confused. Basements go below frost line, sure, but bedrock can be hundreds of feet below the surface. I don't know of any home I've ever seen that has

• tristor 5y ago
  Yes, bedrock can be many hundreds of feet below the surface, and in other areas bedrock can be pretty near to the surface. This is one reason why you should have a geologic and structural engineering report done on a plot before you build (and arguably before you buy the plot). Depth to bedrock greatly factors into the cost if you intend to have piles put in to support your foundation. In some areas, it's not actually necessary to drive piles to bedrock to get similar stability, instead piles are driven to refusal at a calculated depth based on the expected foundation load. In the regions I'm planning to build though, bedrock is nearer to the surface (or in some cases exposed above the surface as an outcropping), which means that the proper way to do things is to drive piles to bedrock. I am not a structural engineer, and I don't know what is necessary where you live, my list was made for my specific purposes and shared because it was asked, it's not an argument in favor of any specific structural techniques, you should speak to a structural engineer in your area.