I have available a 60x40 shop. The space can be heated but it is insulated and generally stays 10-15 degrees warmer than outside temp. Lots of room for storage and/or space to work on a car. Will fit a fullsize truck. Door height is 9ft. Also available is compressed air and 110v power. The space is not empty but I would imagine 20x20 is an accurate measurement of space available. The pictures show a lot of different items but everything can be moved to accommodate anything!