Nothing will last unless you maintain it.
It is particular stressing on any exposed structures in tropical countries where rainfall is plenty, unbearable hot sun and high humidity. Furthermore, the poor environmental control, especially the burning of forests and emissions of burnt fuels, result in acidic rain.
My house semi-glazed roof tiles are now twenty years old, deterioration is now quite obvious. The light brownish zone is the result of the break-down of surface glaze and I can feel the sand coming out from the cement-sand concrete. This zone is likely due to the splash of rain water from sky and the upper roof. The black zone is due to the growth of moss and lichens, which turned black after death and firmly stick to the tile surface. This is in fact the most common problem of roof tiles. I remembered the neighbouring houses all used beautiful red roof tiles, but after 30 years, the roof all become black. I used dark grey tiles, so the colour change is not that obvious.
Normally, water and water jet is used to clean the black moss off, but in view of the danger of the steep slope, unsure concrete quality and water leakage into the house, I decided just to paint a coat of Dulux Weather Shield roof paint over the roof tiles without removing the black moss.
Let's see how long it will last. At least, now it looks better. A coat of paint will definitely help the roof to last longer.
But the cost of the paint is high. It costs about US$40 per 5 litre tin, I have to use 20 tins (100 litres) for a surface area of 12m x 20m on the upper roof.
