Dartmouth, Nova Scotia is home to a peculiar house with a concrete roof. The roof is now leaking and Ron would like to know how to seal it.
Many good coatings are available, but all of them will eventually need maintaining and may even develop leaks from weathering -- as has happened with the present red paint you see on the roof.
A creative permanent solution to a creative roof would be to sandblast off all the present finish and then apply a product called Xypex. This stuff starts a crystalline reaction in the concrete that with time will develop all the way through the slab. Large cracks do have to be fixed first. It is usually used on foundation walls or tunnels, but why not on a curved roof. This will make the concrete completely waterproof through and through, not just on the surface. Then Ron could paint or coat it with anything he wants for the colour without worrying about leaks when the paint starts to wear thin.
Xypex is sold by King Packaging Materials and is available in most renovation centres.