Standard containers: 20ft (160sf) or 40ft (320sf), 8ft wide. Hi-cube: 9.5ft tall (standard 8.5ft). Structural: designed for 25-ton stacking loads. Modifications: cut openings (reinforce with steel), weld containers together, add insulation (spray foam or rigid exterior). Challenges: condensation (vapor barrier critical), narrow width, code compliance varies by jurisdiction. Foundation: pier/beam, concrete slab, or screw piles. Cost: $150-$350/sf. Container: $2,000-$5,000 used. R-value: uninsulated steel wall R-0; need R-13+ added.