I suppose one of the issues is that you say "the cable needs to be external". In such a situation, I would try everything I could to avoid that - I, too, like 'neatness', and 'nothing visible' is even neater than visible conduit!
Well, if I was building the extension we have, there'd be the ability to run cables internally. But with what I have (the previous owner built it) there's no f'in way. Can't even lift a board in most rooms as they seemed to like the "click together" laminate, and other rooms have the big sheets of chipboard (that creaks like heck).
EDIT: So I've had to resort to conduit (metal) round the outside of the extension.
Spent the best part of 10K on that job.
But I have to let it all go or I'll end up winding myself up about it for the rest of my days......
I know what you mean. I get earache from SWMBO about the length of time I take over jobs - but she is generally happy with the end result ... eventually
She also complains that things are "too complicated"
But if a plumber had told me that I was wrong to want soldered fittings, he'd have been "asked to leave" - and in a manner that left him clear not to come back. But then, I do my own plumbing ... slowly. I'm an endfeed person myself - and slowly getting rid of the old plastic.
However, with T&G boards it's a bit different - and I suppose that if the tongues and grooves were strong enough, it would effectively be just one single big sheet, hence 'OK'?
They aren't, it isn't - and the manufacturer's instructions are very clear on that. Again, if I had a contractor telling me that it was OK to have unsupported joints like that, they'd have had a choice of how to leave the premises - on their own two feet, or the same way as their tools.
it really pees me off when supposedly "competent" trades people are ignorant of really basic things. Recently I had a boiler "engineer" (mum's boiler had been playing up, I replaced the leaking auto air vent as they couldn't come round for a few days) tell me that I'd broken the law (I hadn't) and that modulating pumps don't exist
EDIT: I think that's something I inherited from Dad. I gather Mum has had to 'rescue' tradepeople in the past when they've failed to follow instructions.
I gather on one occasion he had a youngish bathroom fitter in tears - the instructions were clear that the wall boards had to have something like a 6mm gap at the bottom to allow for thermal movement without breaking the sealant bead, he'd been specifically told about this, and he'd left nothing. Different person, but same bathroom project, he caught one of them moving a radiator bracket he'd previously set-up just right. Said person said they weren't level - till dad showed him how to check that his bubble was right - it wasn't ! Same fitters also wanted to strip off the packing strips he'd spent a couple of weeks setting up to give them a flat reference to mount the wall boards on
And the BG 'plumber' who wanted to spread three zone valves all over the cupboard floor in spite of having been told "they are going in that space I've marked". Can't remember whether dad spotted and corrected his error before or after he'd soldered everything up