Mine's the same size as Spoon059 - 18x31x10. It's the basic horizontal sheeted unit. Gives center clearance of 12.75'. My county (NC) required 'certified unit' which is: Heavier snow & wind loading, longer metal warranty, professional engineering drawings, twice the screw anchors (every 4') for ground 'foundation', 1/3 more screws in sheeting, and heavier side post to arch rafter braces. I don't have slides and trailer is a 22FB, but planned for potential bigger unit w/ slide. I closed in the back to bottom (which includes metal studding every 4.5'), added two sheets to both sides - which covers within 4' of ground. This keeps unit cleaner, shades rear of unit, and shades sides almost to floor level. Cost $3,200 installed. Built at a storage facility after build crew said they could disassemble and rebuild at new site at reasonable cost. Got from Steel Structures in Mt Airy. They go all over SE. Very satisfied.
2011 F150, SCrew, 5.0, 3.73, 157"wb, HD tow pkg, ARE camper cover, Husky wdh
2010 Jay Flight 22FB