The roof is intended to be used as sort of a mini-park area, so I made a stairway to get up onto it, and a rebar trellis over it to provide shade for people and to help keep the house cooler.
The roof is made of what I call "nylon-cement", a combination of nylon fishnet and cement; in this case over iron rebar. It is similar to ferro-cement construction, except that one layer of nylon fishnet is substituted for the standard three layers of chicken wire.
Here you will see the steps I went through in doing this remodeling project.
Step 1: The Original House
The shed had a cement slab roof that was poorly made. The rebar was set too low in the cement. Rust had caused expansion of the rebar and destruction of the interior side of the cement slab.
The house had a wood and corrugated iron roof. "Polillas", kind of like microscopic termites, had eaten up the wood. Booth roofs needed replacing.
I decided to make a roof that would connect both structures, bridging over the space between them.
The rooftop could be used as a little park area once it had a trellis for shade over it. The view from the roof is very nice.
Step 2: Painting the Rebar
Rust can cause the rebar to expand and damage the cement, so for best quality work it is best to paint the rebar.
Step 3: Zipper Stairs to the Roof
Because I was running low on nylon fishnet, I used the traditional ferro-cement technique for the stairway and roof of the shed. I used the standard three layers of chicken wire over the rebar, instead of a using a single layer of fishnet. It's more work, and the assistance of another person is sometimes needed to help mash down the layers and pass tie wires through from one side to the other. Nylon cement is a lot more user-friendly and can be done alone.
The stairs were the first part plastered, so that I could carry buckets of cement up to the roof without climbing a ladder with them.
Step 4: The Roof in Rebar
I used the stubs to tie wire the new rebar to the top of the walls, so there is some continuity between the rebar of the walls to the rebar of the roof.
Step 5: Bamboo to Support the Weight
The way I do that is with bamboo. With the bamboo in place, one can use the top of the bamboo like stepping stones. It's a little tricky, balance-wise, but it can be done.
The fishnet is held in place with wire "S" hooks and twisted pieces of tie wire.
Step 6: Plastering the Fishnet
Step 7: The "Bridge"
The white is a cement-based roof sealer. The reddish brown is the top coat of colored cement that protects the more expensive layer of sealer underneath it. One can "paint" cement with colored cement, instead of using house paint. The mottled yellow walls are painted with colored cement over the original house paint. It appears to be sticking well to the layer of house paint.
The decorative frames around the windows are just strips of insulation foam adhered to the walls with cement and painted with colored cement.
Step 8: The Trellis
A good ladder is necessary to work at the rebar intersections, tying them with wire. The limit to the height of the trellis is just however high you can feel safe working.
The trellis shades the house and keeps it cooler. It also can provide food, depending on what vines you plant. My favorites are spinach, passion fruit, chayote and zocato (juicy and sweet like a melon).
Trellises can be converted into more cement structure, and new trellises can be added. This kind of architecture could result in a city that more or less resembles a termite nest.
I hope to do a "Termite Nest City" instructable eventually. I can't built a city alone, though, so it may deal mostly with models.
Also, a "Painting with Colored Cement" instructable is on its way.