Building cloakroom toilet under the stairs on ground floor

[Montana78]

Hi Everyone. Just joined the forum today. I've bought some parts already to make a downstairs toilet for more convenience. I got a builder to get the job done. So far I have the way hung toilet pan+cistern, cloakroom sing & taps. I need to ask couple of advice..

1: where will be the best place to get the more important bits like the pipes for water & sewage?

2: this is the design of my house. as you can see the stairs against the wall shared with neighbours. So I cannot just vent through that wall. the drain and sewage will go under the floor through the dining room and out to the side return to meet when the upstairs toilet joins.
I need to know how I can ventilate the toilet. there is a 1 foot crawlspace underneath. the toilet will have just the toilet and the sink. I was wondering if I can just have the ventilation vent the smelly air under the house.. or is there a better way.

3: best place for cheap tiles for floor and walls

Thanks in advance

 

[BertyUK]

the easiest place to do it with proper waste connection will be as close to an existing waste stack as possible. Directly under your existing toilet would be easiest most likely but that is inside your family room. If that isn't an option, perhaps build a small extension on the side of your family room.

 

[BertyUK]

Like this

Edit, sorry just re-read your post. You've already decided where the toilet is going.

 

[Guitar_man]

Pretty Big job fifth g a downstairs loo. Under the stairs is usuawlky a good place if a little tight.
Not sure what you mean about vent, u mean extractor fan?
The sewer needs to connect under the floor to your outside stack, which will involve digging and redoing the sewer.

 

[Ian H]

What about a Saniflo?

If your existing drains start at the upstairs toilet they might not be deep enough to connect into.