Foundations

Sand and gravel ready for mixing. I strongly advise in getting construction materials prices before hand. Also get a good handle into the cost of labor per day. That way when you get an estimate you can calculate what the cost is and figure just how much the middle man is pocketing to get it done. Of course if you are directly supervising it is much easier but that is not my case.

Hand digging footings. Yucatan topsoil is very shallow. There is no more than 30 to 40 centimeters (little over a foot) of organic topsoil and then you find rock. This makes for a shallow trench of no more than 60cm (24") deep for footings. Unlike the north in Yucatan you don't have to worry about ground frost levels and your foundations can be at any depth as long as they are on solid undisturbed rock.

Rebar (Reinforcing bars) Yes, houses in Mexico have lots of it. The good thing is you find it just as you would in the U.S. The denominations are the same in eights of an inch. For instance a #4 bar is 4/8" diameter or 1/2". There are also metric denominated rebars in which case is easy to convert and there are tables to help you do that. A #4 would be a 13mm in metric.

Starting the foundation. A bit unusual method of laying out the footprint. They use lime dust to mark where to dig and laborers seem to know which side of the mark to dig. You really don't see the corner stakes and level lines we are accustomed here in the U.S. But like many things this is how they do it and don't try to change their habit, you may end up with costly mistakes.