I have a first floor flat that has a small kitchen at the front of the flat above the front door. The original kitchen, when the house was built in the 1930's was at the back of the property. The plumbing is still at the back and so all I need to do is put in a new kitchen. The plumbing is obviously still at the existing small kitchen at the front. Do I have to get building Regs to connect up to the existing (adequate) pipework, and install the sinks and shower? And a toilet in the shower room? There are 4 inch waste pipes for both rooms.