You want 8 foot tall concrete walls or are you just putting a couple layers of block down then going to a stick built frame? Makes a big difference. Personally when I built mine it was 14 ft by 12 ft and the back walls were 3 layers of concrete block, then stick built with tin siding. 8 foot walls so I could put a single roll up door. It could also be insulated but I have not electricity going out there so I haven't done that yet. I built mine about 7 years ago and it cost me about $1200 dollars with the cement pad poured at the sametime. I did this myself so that was a basic materials cost.
I want the walls of concrete block all the way up, then I suppose a sheet metal roof. Would like to have a metal door/frame and metal window frames if I can find such.
I've even thought of having the thing built with reinforced concrete walls to use as a tornado shelter (in my part of the country, that's a good thing to have) but I don't know how the walls could be anchored to the existing slab.
