Building Placement

Hello All:
I would love to know the logic/ algorithm or voodoo magic that goes behind where and when you cannot place a foundation… I will be at a place where I am trying to build fairly level no obstructions to speak of and all of a sudden red box. I am not talking about huge places I am talking about a 4 square building and I cannot get four foundation together. Also why cant you mix metal and wood?this is survival we are talking about!!!

Thank you Icon58

i would love multi level foundation houses