We live in a Victorian house and on the 3rd floor there is one large / 2 bedrooms which we are planning to change to 1 master bedroom with en suite. There is no problem knocking down the wall, and it is already a room, so it's not a conversion. However, with changing the layout, the plumbing, adding the bathoom, moving radiators, changing lighting, etc it is quite costly.
We've been given two quotes by one builder (recommended by a friend) - one following building regulations, one not. He is happy to do either and we need to decide. The former is about £3000 more than the latter. He says they are both legal, but following the regs would avoid any issues when we come to selling, and the insulation would save energy.
Does anyone have knowledge / experience of this? We don't mind paying more if it's a good investment, but don't want to do so needlessly. The other builders we've had quotes from have not mentioned this.