I agree with bigreader, I wouldn't make bathroom and toilet into one space.

Thanks - yeh we did debate this but couldn’t land on a design as we didn’t like the shower outcome (felt boxed in), and we did try many other options but none seemed to work as we wanted. not sure this is better or worse than one big room. Our backup option was to put a toilet in the laundry - knowing that if we had to sell and it wasn’t appealing, it was easy enough to remove and replace with a cupboard. This is an issue so close to the kitchen.

Without knowing too much more ( like construction , age of the house , etc ) , I'm assuming the site plan is accurate ? The only place there's any real spare space is in the front , or going up . But I'm going to take a wild guess from the floorplan thats its likely a 1960's or 70s weatherboard place on piles/stumps ?

So going up would be expensive , as it will probably need all the roof trusses redone , new roof , probably load bearing strengthening , all sorts of engineering challenges . Plus trying to match materials is difficult .

Similarly , expanding out the left side or in front will still have problems , as well as matching materials but also even with styles -- do you try and modernise everything ( new windows , doors , wall cladding , etc ) or do you try and match ?

With that in mind , heres a thought that you mightn't have thought of -- in the front wall of the lounge , you have a window or maybe a door , and the entrance door to the right , and the terrace . Have you thought about making that window or door into an sliding door if it isn't already , but effectively moving it and that wall forward ? Basically do away with the standard entrance door , and make a larger lounge , but with a sliding door as an entrance door .

Editted to add ( as I didn't make it clear ) -- that new front wall across the left hand half of the front would be 1.5-2 metres further forward , effectively taking half that front terrace area , and doing away with the existing entrance door , and the associated 'inner' hallway wall can also be removed .

From there , maybe spin the kitchen or even move it over to the dining room ( maybe a bigger window ? ) -- the idea then is to 'wall off' the rear meals/family area , which could become the master and en-suite .

Okay , that cuts down the rear indoor/outdoor flow , and it combines the lounge and the family room into a bigger room , so not ideal , BUT it does give you a large Master bedroom and a 4th bedroom at that , almost within the same walls , without a huge number of downsides .

Maybe something to think of ?

Seperate toilet with basin is a must. Can you provide dimensions. Extending the shower out towards the vanity with a glass screen and add a sky light can reduce box feeling.

Thanks Kate - this is an iteration of an ’all in’ bathroom with dimensions. note - we took some space for B3 robe, so this further complicates it. you also cant put a door to the left of the vanity (toilet direction) as this is now past the hallway / kitchen door

Thanks Pottsy99, its a 1960s brick veneer on concrete stumps. refreshed early 80’s. its definitely something to consider - i do see challenges with how’d you’d tie in the pitched roof, footings in order to keep the brick theme etc. unless it become a light weight addition flat roof.

Okay, first with your plan, you only need 800 between walls for a toilet width, You could put in a wall for privacy or increase vanity width.
I’m questioning the value of small robe in bedroom. with bed room length, and my daughters is similar size, I would move bedroom door down and add a full width robe along existing wall

Here s an alternative

Thanks Kate. We actually did have this design but were told that 975mm between vanity (500 deep) and shower (900) wasn’t enough space - do you have another view?

Also, to fit the toilet and small vanity we’d need a width of 1050 for the toilet room, meaning you’d drop the shower back to 1000 or 1100, depending on how much space either side of bath you needed for cleaning. Are you suggesting ditch the freestanding bath?

always best to plan the long term extension and then do the work in stages rather than make changes that may block future improvements but what is the width and length of the whole block and distance of the house from all four boundaries, can you drive into the backyard and is there an existing garage ...your site plan suggests extra space at the front that could potentially be used better but some photos and a Google Earth view of the roof would help and keep in mind your children will not be small for long and i would never have a free standing bath at the expense of a separate toilet there must be better options for the new bathroom but before changing the old bathroom you should consider the whole house

An inset bath will need less room. Def worth changing to maintain a separate toilet.

pending more details i'm wondering about rearranging the hall and kitchen to make more space for a generous bathroom, extra biw and and storage with comfortable furniture option for the smaller lounge

Love that Okl. 5 m is ample for lounge and gives space to where it is needed

Interesting layout ideas! We need to trade off the cost / effort vs outcome (still only 3 bed and one bath). Moving the hallway was one of our previous concepts, but if we did it we’d push out/down that whole side in order to get the en-suite and extra bed.

Your bathroom advice has cemented the need for a separate toilet. Here is where it landed. We’ll probably opt for a single basin for more vanity space…Thanks!