Which profession do I need for this job?

[RosesforMama]

We have a large bathroom which we want to split into a smaller family bathroom and an en suite. There is a tricky window which may need making smaller. DH is much less convinced than me that this is a good idea, he wants to just replace the family bathroom but I think as it definitely needs refitting in the next year, this is the ideal time to just go for it. DH has now said I can get someone in to make a plan so he can better see how we could split the space. Would this be an architect? Interior designer? Builder?

Ideally it would be great to find someone who can make mock ups and show DH how this would work.

You want a general builder.

Yeah, general builder. They can sub-contract a plumber, if needed. My dad worked in the building trade, I think that's how he would have worked.

Will a general builder design the space though?

If you go to a bathroom place they will arrange it and charge a fortune.

A general builder can 'design the space' or even just 'decide what goes where' but you will get better outcomes of you go in with your layout ideas and use the builder to work out practicalities- don't just assume anyone doing design will think of all the details of how you use it.

You can 3D design the space yourself in SketchUp. It's helpful but not essential to know which way your joists go when thinking about drainage but you obviously know where the soil pipe is and that's usually the biggest factor. One man band builders are often happier to just build to your plans, larger or more experienced ones can help but I'd rather choose my own bath, toilet, shower cubicle, mock up where it all goes and then show this to a builder to ask them for anything they'd change.

We've replaced windows with similarly sized windows just using a builder (plus window company) - someone else will be able to tell you what the planning and building reg implications for adding them (I presume a lintel calculation could be involved)

You will find that a good, experienced, general builder will have done this sort of thing before and can offer useful ideas. A lot of builders actually do 'design and build'. It is very easy to draw a plan yourself though, either by hand or with a programme. You must have some idea what you want. E.g. could you replace the one window with 2? Not difficult at all.
Yes, stay away from these bathroom design companies - they will charge you double the price for the same end result.
You do not need an architect, unless you really want to throw your money at it.

Draw a floorplan on squared papr and the floorplan obsessives on MN (incl me ) will do it for you!

@minipie

Draw a floorplan on squared papr and the floorplan obsessives on MN (incl me ) will do it for you!

Ah, good idea! Will measure up when I get a chance.