garygumps

Hi
I have a decking/balcony part of which is roofed with black slate tiles. This flat roof bit is above a walk-in wardrobe below.

Basically, the grouting is showing cracks and when it rains heavily, the water puddles and seems to penetrate to the room below. i have applied coats of Thompsons Water Seal, but this would not stop water seeping through cracks in the grouting?

I dont really want to have to go through the expense and hassle of ripping it all up and re-doing it. Is ther some sort of waterproof paint /sealant type stuff available?

I remember seeing some decorators "painting" the roof tiles and lead flashing on a house round our way.

Thanks