Do you have any other access to the backyard? Lane at the rear etc? If not... I like your plans but I wonder if you will miss the access down the driveway. Possibly a problem should you sell later on, or should you need to bring large amounts of materials etc into the rear yard. I'd think about using the front of the house for all the bedrooms. Possibly the sun starved middle room for the master suite. Extending it though to the room you have marked as pantry. I can't see the dimensions, so I hope it's big enough. And use all the rear space, minus the bump out, as living. You could maybe pull the kitchen into the centre, looking out to the yard, pantry + laundry behind it against the for mentioned bedroom. Splitting the living area up a little. And giving you much more living space.

After reading all the suggestions I tend to agree with Kathy Grant. Why do we need ensuite. I certainly don't like flushing toilet in the middle of the night right next to my bed , or someone having shower at 6 am when I could be sleeping till 8am. Can somebody explain what is the advantage of having ensuite to having just 2 full bathrooms. And not to mention open plan bathroom/ bedroom.

That study nook may end up being dark , and you may also 'overlap' some other windows too , like the WC and laundry . I suspect a lot of us would like to see some pictures , the materials , the exterior ( brick , wood , concrete , etc ) . Just a thought , but if you extended the 3.1 bedroom by a metre or so to the left ( as its shown above ) with a 800mm or so wide window on this new protruding wall , made the existing toilet effectively the hallway , put the toilet ( and maybe a bathroom and a study nook ) to the left of that , then Bed 4 at the end of this new hallway ? Depending on the style of the house , you could have large windows or even a sliding door or french doors along the hallway , or higher windows only , of course windows in all the other rooms , too . Cost wise it will depend on the work needed , it may be no more than your plan ( which I gather is 2 doors from this study nook into 2 bedrooms ? ) or more expensive , but I suspect it will be better , more usable , look as good externally but better internally , and not be such a compromise ?

My daughter ran her business from her bedroom until they could afford a 3 bedroom house, their 2 bedder with two boys and no where else to fit an office was a very difficult time which thankfully they all survived. Having your office in your bedroom should be avoided at all cost, as you never leave the office behind as my daughter found out. Your bedroom is where you go to relax , I certainly wouldn't give up my sanctuary for anyone, even my kids. You are there full time so it makes sense. Your house already has enough rooms, except for making a small change to allow for another bedroom albeit small next to the bathroom as per my suggestion, Both of these rooms have space for the boys to have a desk (they don't need a lot of storage being part time) The desk in the living area can be built in to hide an office. This is a low cost solution and won't damage resale value. If down the track you can afford the new deck, try to work out to fit a room underneath as a hang out (media) area for the boys. not sure about WA but rooms like these in some states can have ceiling height at 2100, depends on what name!! you give them. My son is in a similar situation to you, except he now lives in a Studio Apartment in Sydney, so when he has his two kids 50 50 they make do in that space and seem to manage very well.