Breeze blocks

[demographic]

No idea, thermalites are usually used for above DPC level but I've seen em used for external skins as long as its rendered. That's mostly rendered for looks I assume though.

I would have thought that if they were standing in water that freezes and thaws a lot out it would cause them to erode over time but they are bound to last for quite some time, err, I think.

 

[British Red]

Slap a coat of bitumen paint on em Mary - thin the first coat with 10% white spirit then lay it on thick. That'll waterproof the heck out of them.