Are external water feed pipes allowed?

pieroabcd

Hi, 
Today I asked the plumber if its possible to install a bidet feeding it with water pipes coming through the sink, that is on the other wall. 
 The drain is not a problem because the bidet would sit beside the toilet.
My idea is to derive hot and cold water from the sink and pass them along the wall, externally and covered by something like plasterboard. I prefer not to break the floor tiles and open the floorboards underneath. 

He said that he has to check the building regulations. 

Does anyone know if a setup like this is allowed?

Thanks

FreeBear

Whilst it is possible to run hot & cold pipes externally, you will need very thick insulation on them. There will also be a huge amount of heat loss on the hot water. Using plasterboard outside is a bad idea as the stuff will break down fairly rapidly as soon as it gets wet. and quite frankly, it is going to look piggin' ugly.

If you can't hide the pipes under the floor, your only real option is to surface mount them on the wall inside the bathroom. Alternatively, take the ceiling down from below (which I have done in the past). Just don't notch the joists from the bottom - It will weaken them and is not permitted.

pieroabcd

Thanks. 
Indeed the prospective bidet would be exactly under the sink upstairs