footings vs pylons

smarbaga

hello all : first post here
i am putting a 12' x 34' addition the back of a house, 1 story.
i was originally going to put sona tubes and insulate the floor.
cost of this support and insulation is about $800. ( no problem)
i am now thinking of about pouring a footing (outside parameter)
using 1" ridged styrofome on the outside of the footings. (underground)
footings will be 6" above ground level.
placeing a knee wall on top of the footings ( 2x6 pressure treated).
knee wall will be 2' high, and insulating this wall with styrofoam.
lightly insulating the new floor with fiberglass batts
the knee wall will be sheeted and covered with sideing.
do you think this would be a better idea than heavily insulating the new floor? ( stopping the some of the cold before it comes to the floor)
thanks in advance for your advice and sugestions !
reguards garry

dec-conc-artisan

within WHAT parameters ? ? ?,,, what parameters are relevant ? ? ?,,, building code ? ? ?