On 23 Sep 2005 09:58:05 -0700, a particular chimpanzee named
randomly hit the keyboard and produced:

Hi I want to install a downstairs toilet...
we would only need building regs to fit cloakroom?

Not 100% sure about "only" (99% sure though), but certainly Building
Regulations will apply to the extension and alteration of a drainage
system. Building Notice will suffice (in Eng & Wales), and the
relevant bits are Parts F, G and H.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed?"