ROOF PAINTING TIME

The white definitely does keep the house cooler. The roof on the house we are renting in Riviera Alta just was done in February. It was terracotta before and now is white. Today was the first day I put the fan in the bedroom on low.
John's information about Fester is, IMHO, bang on. When we re-did the roof of our house in San Pancho (five years after construction), we used 10 year Fester Acriton and a membrane and John's instructions. The contractor we used said he had never seen a thicker or better impermabilizante...icky stuff to work with but more than does the job.

Sparks...it's not just the sealing of the tile. The tiles come in various costs per tile. You want a tile that is smooth on both the top and below...in 2005 that was a difference of 2 pesos per tile...30 tiles to a square metre.
A peaked roof has the advantage of having the sun on only half of it for half the day. Actual real clay tile roofs are cooler than cement only with a white coating roofs.
Gringal, friends of ours in San Pancho had a flat roof and low ceiling height. It was very hot in the house. They built a frame about 1/2 metre high and, leaving an air pocket about 1 foot high, covered it with palm fronds...instant and prolonged relief from the heat.