Exterior adhesive for tiles

NoMoreNails, then grout them with sand/cement mix from the DIY Shed.

Thought this was PVA based and therefore not waterproof?

Ordinary ceramic floor tile adhesive will work fine for this, although the smallest bag is likely to cost about a fiver or so. An ordinary mortar mix with some PVA in it would also be ok, although you'd probably need to support the tiles until it goes off.

Just had a thought - mate with a boat was telling me last week that he sticks junks of ply to its interior using silicon sealant and finds this sticks the wood well enough to support all his weight. And he's heard of plumbers sticking corner handbasins in with it. What do you think? It'll fill the irregularities and the suction *should* grip the tiles???

Richard

Just about any one of hundreds of water resistant sticky stuffs will do for this job - it's hardly structural. The best choice will be something you can make a neat fillet of around the irregular brickwork, etc.

I'd guess silicone would need supporting until it dried, though. It would certainly be strong enough when dry - I recently removed a window frame which was sealed with it at the top, and two of us couldn't pull it free even although it was just hanging on the silicone - I had to cut it with a knife.