The imperial 12 ft. w x 20 ft. d metal garage shed is made from heavy-duty galvanized steel. the large metal panels are coated with a heavy duty hot painting process for long life. the garage/building has strong thick galvanized steel beams, columns and a metal reinforced roof support truss system for extra sport.. 20 x 20 shed in excellent condition, only had this a few monthscomes with original box grab yourself a bargain for 6600.0 feel free to contact me with any questions details: home, sheds, deluxe, double, door, garden, shed, canopy, payment, shipping. Diy sheds are cheaper to build than pre-made sheds, and because you are building them yourself from scratch, you can be sure of the quality. this is a key point, because with a pre-made or flat-pack shed, you can never be sure that the lumber being used is of good quality, or even if it came from sustainable sources (if that’s important to you)..