Upstairs loo

Personally I wouldn't want a loo in my bedroom but its what you want that's important but be aware that a lot of people would see it differently should you ever want to sell the property assuming you own it.

I am not sure this is permitted under building regulations.Basin would be OK, but not loo. That has to be properly separated from any habitable room.

My God, Monica! I have two upstairs loos; both in bedroom annexes. Am I illegal,

But there is nothing to stop you having a "temporary" caravanning Portapotti standing near the basin, like an invalid's commode, with your screen round it. It does flush, but is not connected to the sewage system, so you'd have to empty it at regular intervals and refill the flushing water container. www.thetford-europe.com/

Is the alcove close to the downstairs toilet stack or would you need a box that mashes it all up to sludge so you can use ordinary pipe work? A macerator? If that it's workable then plasterboard stud work is v cheap to screen it off.

Look at a saniflo system which is a macerator. Only drawback, they are very noisy.

If you have room for a screen at the toilet, would you not then have room for a very basic stud wall, like a screen only more permanent. No need for double cavity or the like.

You could have a sliding door. Some of the modern ones are quite nice, not like those of years ago.

Perhaps your assumption that an ensuite loo or shower room is too expensive may be wrong. Why don't you ask an architect to advise you? Most architects do not charge for an initial visit. Check out the Architects Registration Board (arb.org.uk) to make sure you are speaking to someone properly qualified.

Don't go with saniflo. When they go wrong the shit hits the fan.
If I want privacy in my ensuite, I just lock the bedroom door.

To put a WC in any part of your house you have to conform with Building Regulations. These require compliance with electrical, water and air quality regulations.
If it is to be an asset to you, both in amenity and value to your house, then seeking advice from a professional would be the way to go.
Over the years we have added bathrooms to houses we have lived in and have just got planning permission to add a downstairs WC.

I agree with j52 100%. You must conform with Building Regulations. The house would be very difficult to sell if you did not have the relevant paper up to date. It is not worth the hassle because if it is discovered that you have gone ahead without the relevant approval, at your expense you will be forced to remove it and possibly fined. Is it worth it?

Best thing to do, initially, is to contact your local council and ask to speak to the building inspector. In my experience they are very helpful. You don't, at this stage, need drawings or anything, simply explain what you want to do.
As each council organises things differently, I don't know whether they would offer an appointment at the offices, or do a home visit (I have had both). It is fine to do this at the initial stages, and indeed, because they are so experienced, may make helpful suggestions.
Without knowing the general layout of your house, drainage & plumbing systems, it is impossible to say what may, or may not, be allowed.
However, I would add that it may be worth your while thinking even more broadly about making your home fit to live in as you get less able. That is when talking to a local builder may be helpful.

Depends on what you muan by alcove. If you can fit a door frame and door, no problem. Plumbing wise you might need a macerator but these have been improved lately.

And yes you do need building regs

Life was so much easier when we had chamber pots.

beammeup shit hits the fan

True story. Engineer was fixing our mascerator when it blew.
He was covered in the brown stuff. He eventually saw the funny side of it. Never go near a Saniflo - they are unpredictable.

Depending on the size of your bedroom, building a stud wall as has been suggested - sounds a good idea. It will pay for itself to have it done properly when you come to sell. We have a loo upstairs and downstairs - I don't know how I'd manage going to the loo in the night otherwise, especially if I have the GC to stay.

My bathroom/toilet is downstairs as well. I would love an upstairs toilet, and have a walk in cupboard in my bedroom that would (just) accommodate a toilet and tiny hand basin, but there`s no direct water supply to it. I`ve been wondering if it would be worth finding out the cost, but don`t want to die of shock!

Beammeup, I understood OP said the loo would be in the bedroom with only a curtain or portable screen round it. I think that would breach building regs. I think providing the loo has a proper wall and door, you can have it virtually anywhere.

I am not saying this with absolute certainty but suggesting that it should be checked out otherwise you could have problems when you sell.

I take your point, Monica, but the bathroom is in an alcove off the bedroom with the loo just round the alcove wall, so I think it is alright. We are the third occupiers of this house and didn't have any problems when we bought it. The other bathroom (home to the rogue mascerator now replaced with civilised plumbing) is a converted small bedroom with fitted furniture off another bedroom which was an extension.

We had a Saniflo on a toilet in an ensuite. A visitor put a tampax down it and it stopped working. OH took it out and he and DS took it out into the garden to open it up and it was as clean as a whistle inside - just as if it had been scrubbed out! The string from the Tampax had wound round the blade thing. They unwound that and all was well again so they just refitted it. They do come in different sizes - ours was a small one which just had the loo and basin flowing through it - the bath water went straight through the the down pipe.

Over the years building regulations have changed and become more exacting. Things done in the past are left until you want to change something, or could be problematic when you want to sell a property. A surveyor will comment on anything that does not conform to modern standards and building societies will have an opinion regarding mortgage viability.
In short, electrics have to be safe, away from water and steam, adequate ventilation via an opening window or fan, that ventilates at a certain rate and water supply and drainage of foul waste has not to contaminate other water supplies. All has to be checked by the Building Standards officer.

About 35 years ago I spent a few days in Holland. The hotel claimed the room had its own bathroom, which amounted to a shower cubicle and macerator-type loo next to it. No privacy, it was just against one of the bedroom walls!