Measure the length, width and height of your RV. Include any objects mounted to the sides, rear or roof of the vehicle, such as a bicycle rack or antenna. The unit should be at least two feet longer and higher than the vehicle and four feet wider. A typical RV storage unit is around 14 feet wide and 40 feet long.
Decide where on your property you want to build the storage unit, taking into account enough square footage for the unit itself and a place where the RV can be driven in and out of.
Construct the frame of the storage unit to its required height, length and width. Sturdy 2X4 lumber will work; you will need four pieces equal to the unit's length, four for the height and at least two for the width (for the unit's roof). Also, cut out diagonal joists and nail them into each of the frame's top corners to support the roof.
Cover the top of the frame with a large tarp or similar material if all you want is a canopy-style unit. Nail or screw the tarp onto the frame's top edges. The canopy can be extended all the way down the sides of the unit if you have enough material.
Add the sides and roof to the form instead of the canopy if you want a manger-style unit. The sides can be made of anything from cold-formed steel to aluminum siding. Anything made of sheet metal will require a power drill or bolts to affix it to the frame.
Add a door to the front (and possibly back) if you want a fully enclosed storage unit. The easiest method may be to take a sheet of wood the same height and width as the unit and fasten it to the unit with hinges. Then attach a handle and latch at the other end for opening and closing.
