Last weekend I built a thin shell 5'x13' cement deck. I had a wooden frame in place already. I attached 6x6 welded concrete reinforcement wire to the top using "U" nails. Then I stapled two layers (running perpendicular to each other) of window screen over the wire. I mixed a slurry of portland cement, grade c fly ash, and a mixture of water and white bonding agent. I used a plastic putty knife to scrape the slurry through the screen. I let the screen dry about an hour. It had a texture like canvas and was not quite as brittle as fiberglass. I covered the screen with a layer of expanded metal. I did not attach it. The metal wrapped around the step and covered the whole top surface. Then, I mixed 1 portland 2 sand and 1/2 flyash plus 1/10 volcanic ash with a plasticizer and parged it onto the screen and metal lathe. The decking surface is about 1/2 inch thick. Its waterproof and has a little flex. The whole surface probably weighs about 300 pounds. The materials, not including the framework cost about $50. I didn't take pictures of the construction sequence, but I will post a picture of the deck soon. I plan to put on one more layer of lathe and cement.