First look at this pictures:

http://diversifiedstructures.com/images/apartment_complex_photo_ghbe.jpg

http://www.insurancehubavenue.com/wp-content/uploads/2009/11/apartment-complex-insurance.jpg

Those size are the apartment complexes i will be talking about...

Idea #1: Reinforce apartment complexs of wood if they cost cheaper= if an apartment complex of cement the size i showed you cost you: 300,000 and the apartment complexes of wood cost you: $20,000, then reinforce them with wood, the whole thing...Put it 3 layers of wood that way if there is a fire, it takes the fire longer to burn 1 apartment (which will have sprinklers) and that way the firefighters can get there on time....

Idea #2: Thin type of Cement: I remember in Panama they showed a type of cement that was: half as tick as a regular cement (is cheaper than cement) maybe something half as thick as brick also and you build the small apartment complexes....

Idea#3: All the old cars of the world that go to junkyards recycle them, all the ships in the bottom of the ocean: Their iron, melt it, and mixed it up with another metal so they make: Steel and this way you make: Steel small apartment complexes OR use the iron as framework and pour a small coat of cement (5 milimiters thick coat of cement over the iron) so as to not see the rust....Let me guess someone is going to throw a punch and make a hole through the cement?