Exterior silicone/sealant

[Cielos]

Thanks for your replies

Pool grout was what was in there, but the sun has made it crumble - unless it wasn't mixed correctly which is entirely possible

I was advised by a Spanish builder to use the silicone as it's more flexible and the UV resistant stuff will last a lot longer?

[Elgin]

I haven't used it yet but I have recently bought Ceys Silicona "Obras Construcción".  It claims on it

Seals and fixes all material

High resistance to outdoor conditions and UV

Maximum adherence and elasticity

I think it cost about €4 for 280ml

[Cielos]

We are currently having to regrout tiles on a flat roof

Can anyone recommend something that is flexible/waterproof - and can cope with UV rays?

There's lots to choose from in the shops but I'd like to go with something that someone on here has used and is happy with

Thanks!