Workshops are never too big. Your activities are like the perfect gas, they expand to fill available space.
Fifteen years ago moved from suburbs with all sorts of restrictions and crowding to 2.6 acres in the country. Wife insisted that shop be OUTSIDE of the house so debris would drop off before coming inside. It has turned out that 2.6 acres is all that one person can care for by himself so i scored on that.
Previous owner had kept a couple of horses and other equipment and had a 24' x 36' pole building on the property that was already supplied with 220 volt power. Had that building shell remodeled to close off sliding barn doors and provide 4 personnel doors, one in each corner, and a 9' roll up garage door in the middle of a long side.
I divided the interior into 3 sections each 12' wide and further split the north section into 2 rooms; one about 12' x 16' and the other about 12' x 8'. Installed double insulation and dropped cieling with fluorescent lighting. Did my own wiring with gov't inspector for insurance puposes. Note; instal electical outlets 4' above the floor so you don't have to stoop over and so that your benches don't cover them.
South room is office, library, parts storage. Center room is wood working with bench, planer, band saw, disc sander, drill press, stock blank storage. Large north room is metal working with mill-drill, metal lathe, drill press, work bench. Smaller north room is "dirt" room with grinder, polisher, belt grinder, welding soldering and brazing.
Doors are in corners so that you are never trapped in case of fire. All interior walls have plastic windows but the only outside window is in the entry door to the office. Inside doorways have 4" wide strips of plastic overlapping in a curtain to confine dust somewhat but still let you go thru with your hands full.
Heat is by 1500watt heaters from Lowes. We have a mild winter climate in Puget Sound area.
I keep telling Dave Rase that he made his new shop too small!
Dave D.