All exterior walls are made of Insulated Concrete Forms (ICF).  These open interior foam blocks are filled with steel reinforced 4,000 psi concrete.  Steel anchor plates are positioned into the top of the concrete wall with 5/8" steel anchor bolts every 24" to firmly secure the steel roof trusses while vertical steel reinforcing rods placed every 24" link the walls to the slab and footer foundation.  This tying-in of the walls to both the foundation and the roof yields an extremely strong construction far exceeding conventional stick built homes.  This design offers superior resistance to hurricane, tornado, and earthquake forces.  ICF walls can withstand hurricane winds and 200 mph wind debris impacts. These walls are also termite proof, rot proof, and will not support combustion.  Most impressively, they reduce energy costs up to 70% below conventional wood or brick homes.   The walls, like the foundation, also serve as thermal mass to maintain a more constant day-to-night temperature.  Not ever using ICF blocks, I spent a very long time researching the best blocks to use.  My research led me to Amvic Building System. They turned out to be GREAT with no problems.