The Basement Walls... Eterna Building Systems or Rastra is what we used for our basement walls. It is made out of stirofoam and cement and are bigger than block. It is more expensive but only took Jorden and JT Lines a couple of days to put up all the walls! The ceiling in the basement is 8ft 9in or 7 rastra courses high. Maren, our math genius, helped measure the corners and I got to put this cool expanding foam in the spaces between the rastra, it's bright orange. Just a side note...I really don't need to help work on the house...I just do it cause it's fun and then I feel like I'm helping. :)