How to Watching concrete dry

Concrete has to be constantly watered for 10 days whilst it cures. In England we either use sacks or old newspapers to retain moisture, otherwise the top layer will cure before the lower layers, thereby causing cracking and shrinkage at different rates. Sahara is a waterproofing additive, which is usually used in bathrooms where there is constant moisture. After the roof has cured,I would find the cracks and cut them into a v shape and fill with hydraulic cement. Then tile the whole roof and make sure the tiles sit on a bed of cement mixed with Sahara, with a slope so there is runoff. More expensive, but should last for many years.

 

And before you stick the tiles on, put several coats of Sahara, just to make sure.

 

Told my team this 100 times when doing drive way all for nothing. Why listen to Me? They always know better, now have cracks all over.......

 

There are many reasons concrete cracks, the number 1 reason? It is concrete.

 

If the roof had some slant for drainage, probably wouldn't be too much problem with water coming through a 100mm slab. I would surmise that corrugated tin roofs in the Philippines sometimes need a treatment after the galvanizing fails. Back in the bad old days people in trailer houses in the US used to put a product called Coolseal on top of their trailer houses, to leak proof, stop corrosion and it was silvery in color so possibly reflected some sunlight. As a boy in school I had an odd job applying it to the roofs of 8 trailers in a trailer park. I would also paint large LPG tanks but I digress. There must be some similar product in the Philippines that you could apply to the roof. It sticks like tar but is a lot thinner when applied. The stuff is probably expensive for 4 liters/1gallon but the job should only take minutes and should be good for 10 years or more.