Hi does anyone know if there is a product i can put on my sandwash roof to stop it leaking,cant find the leak,so maybe its just coming through the sandwash and concrete,its a big roof(200sqm)so its either tile over the top with some cheap thai tiles or find some sort of sealer,any help would be great.

I used to specialise in roofing in the UK, flat roofs can be quite a problem and somtimes very difficult to locate and repair leaks, is the roof leaking in a location or in several places?

have you any hairline cracks in the roof? check around your parapet wall for slight gaps where rain water can run in.

now in all honesty I'm not sure what products are available in thailand but for hairline cracks in the UK there is a sealer that is clear and quite low in viscosity, aplies well and would not ruin your sandwash, however

its only any good for hairline crack, needs to be bone dry for application and is not a complete remedy.

there is also a liquid rubber sealant that does a better job, you can apply as many coats as you like and is a stronger repair, however this is coloured and will change the appearance of your sandwash,

My suggestion is contact a roofing specialist who should be able to point you in the right direction. like a said flat roofs can be a nightmare, I once found a leak that was actually back tracking from a window

sill header on the exterior of the building and not directly from the roof.

Good luck and I hope you solve the leak.