Hi Natalie,

It is a good start that all your existing plumbing is in the same zone. I assume there is a concrete slab under the laundry floor? If so, this can be where things can get expensive.

However, it shouldnt be too much of an issue to connect a toilet with a "P" piped bowl (where the sewer pipe goes out the back of the WC instead of into the floor) on the external wall and incorporate into the existing sewerage system. To save further, you could also have a raised shower cubicle wherein the floor drain can also be piped directly to the outside instead of under the slab. They are not particularly pretty, so it depends on the needs of the users - is it for the use of guests or to save the bathroom upstairs from muddy feet? Before you make any purchases, get a plumber in to trouble shoot some cost saving ideas. Once you have nutted out those issues, it will just be a matter of being practical in your sanitary ware and finishing choices. Good luck with it all!

You're most welcome!

I'm sure there will be some bathroom trade experts that will chime in soon that can give you a better idea of pricing - but it helps to have a concept in mind before anyone can provide anything vaguely accurate (can i even say "vaguely accurate"? lol). If you post an image with your measurements and a couple of photos, a few renovators will be happy to give you their 2 cents worth too. to get you thinking, these are the questions I would ask my clients before starting a project:

What is the scenario for your mum using this potential bathroom? Have you thought about future proofing - as in, you may need to think about easy access for her down the track. She may one day have trouble negotiating a small, framed shower cubicle.

What sort of storage does your mum need? Also, lighting and possibly heating?

Also, will both doors be necessary? It looks like a decent sized space - guessing around 1.8 x 2.5ish meters? - but you will have more options if you can shut off the exterior door.

I will post a really basic floorplan that you can show your plumber. This will give you an idea of the higher end of costs if you wanted a large shower. You can also ask about an in wall cistern to to save space, but they can be $$. But then again, You may not need it.

hope this helps you get some ducks in a row ;)

I am literally amazed at how helpful you have been - consider myself glued to this forum during our reno journey haha! We can definitely block the door accessing outside off so that layout looks ideal. Just what I would be thinking! Good point RE her ageing (probably won’t mention that to her her ;)) but good point to think about. She’s actually emigrating her from the UK next week after a 5 year parent visa wait, so it’s Going to be a big couple of months!

depending on if you want self contained accommodation for mum or shared rooms my suggestion uses part of the front entry and old laundry to create a self contained granny flat with separate access to the garage and laundry but the dimensions are inconsistent so first measure all the rooms so that you have an accurate plan to help make suitable suggestions

and if you want a more economical downstairs shared bathroom, lounge and study with a private bedroom for mum

but keep in mind that accurate dimensions will decide what's possible and consider access from garage to upstairs and upstairs to laundry with any changes

Thank you! all this info is fantastic and yes I think we’ll look at a combo of plan a and plan b, moving the laundry into the garage. After revisiting the house the window is actually in the ‘laundry’ the the door is in the main room. We’d look at adding a kitchenette too and initially probably keep the space studio like but possibly add some walls later. so will consult the plumber With these ideas and go from there,