[Skirkpat]

Unless your building codes are alot more relaxed than ours, you will nneed to pour a footer below the frost line on undisturbed soil, usually 8-12 inches thick and twice the width of the walls, so 10-12 inches wide, then you can use cinder block, or concrete to grade which up there is probably 4 foot or more. the last gagarge I built, we extended the concrete 3 foot above the slab with 10 foot 2x6 walls to give a 13 foot ceiling, with a ledge and rebar bent at a 45% angle to to tie the slab floor and concrete walls together, and dug a 12 inch trench through the middle both ways to form a support under the slab. the slab should be at least 8 inches thick, and the thicker the better. Our foundation 10 years ago cost well over 4,000.00 and we did not pay any labor. a good garage will start at 10,000.00, and thats you doing most of the work.....you will get alot of that out when you sell the house, but not all..just be aware of that.