Here we have a lot of wasted space under our deck. It has just under 6 foot of clearance and is about 10 X 12, so it would be ideal for a storage shed. The first problem is what to do with the water from the top...

Here is my solution. I ripped some 1 inch strips from treated 1x4x6 boards and rabbeted the edge. I then caulked along the rabbeted edge and screwed the strips at an angle so that water would be directed towared the front of the deck. I then slipped in some corrugated vinyl roofing material, so now there is a ceiling directly under the deck. any water that drips through the decking material is collected by the roof panels and the channels and directed out the front. It works great.

This is the completed storage shed. The material consists of 4 dog-eared fence panels attached to the inside of the deck frame on top and anchored at the base to a frame of treated 4X4 timbers. The slots between the fence panels were covered by ripping 1 inch wide strips of fence panels and attaching with screws from the back. Red concrete patio bricks were used for the flooring and in front of the door.