I am not sure if the crawl space/basement question is being directed to me. However let me address the question as though it is. Here in Texas a basement is not a common house addition. Due in part to the extreme movement of the ground and changes of. Texas ground (alot of which is clay) has a habit of cracking very wide and deep due to the long periods of high temperatures and dry seasons.
That being said, we do not have a basement under our house. The house was built to follow the lay of the land. The lot for the greatest part is rock. We did have a soil analyses done on the property. Once you cleared through the top soil of almost 2 to 3 inches, we were looking at rock.
The exterior walls run from the ground to the rafters. The floor frame is mounted to plating on the Eco-Block, with steel I-beam providing support for joist as needed. Flooring is tongue and groove 4x8 sheets of 1 5/16" plywood. Over this is 1/4" concrete backer board where tile was laid. Under the house, the ground is covered with a thick sheet of vapor barrier material which is sealed directly to the Eco-Block. The crawl space provides anywhere from 3' to 6' of head room. Under the bottom floor (floating concrete) of the two story part of the house the crawl space is limited to around 30" of space. Due to the lay of the land and how water sheads through the layers of rock, we installed a French drain to drain the water away from the house.
Even the garage floors were poured concrete which is raised off of the ground from 18" to 24". The garage floor pans were built with the use of I-beams and stainless panels and alot of rebar. We had also planned to float the back deck and stain the concrete, but later decieded to tile over the concrete.
Again by building using these ideas the entire unside of the house is conditioned air space which houses the HAVC vents and ducts. So we have very little loss in the efficency of the units. The crawl space can also be used for storage if need be. Under the rear foyer is like a fortress, it equates to a room enclosed on four sides by concrete filled Eco-Block, with a ceiling (which is the foyer floor) of 6" of concrete, rebar, with I-beam supports. The area measures 10'x14' with 6' of head room.......makes one heck of a storm cellar.
The attic was insulated with the use of spray foam, which is from 7 to 8" thick.
If I can answer any other question or provide any additional photos, just ask.