hi we have about six months ago now, re done our bath room , similar size to yours, and , i can take some photos and email them to you , we have maximised space, and walls , put in a white stone bath under the window , it is a metre in width , with a cool water spout coming off the centre under the window we pu t afalse ledge in to sit , candles etc on , , we tiles floor to ceiling, off white , wall mirror cabnit with three mirrors , inset into the wall so its only sits out a we bit from the wall tiles , floating bath room vanity , so that it makes the floor space look bigger , . matching stone square basin sits ontop of the vanity to one side so plenty of room to sit all your bath room stuff when need be , seperate shower all tiled as well , with inset , shelves for shampoo etc, also , when you open the bath room door and walk in when you close the bath room door behind it next to the shower is a very narrow floor to ceiling shelvec for towels, now the hole is there we jaust havent got the shelves put in yet. , we gt loads of comments as the bth room dosent look small evn though it is , , most expensive item the sqwat extra wide stone bath , made to order basin / tap ware and shower spray thing ,oh and the white stone vanity which we had made to order as well , due to the sizing .

I have only seen one wooden bench top that has managed, over time, to keep the wet out and avoid that black mouldy creepage where the water splashes behind the taps and around tap inserts. It was built by a carpenter and then the owner applied oil to gain the colour desired before applying several coats of marine epoxy (several = at least 5), sanded back before every new layer. It was burn proof and the colour locked in by epoxy coat with no maintenance required (until a visitor put a burning pot on it and left it there while attending to fire on stove, still... only left a black ring. That said, the owner promptly got out the sander and ground back until black ring was no longer charcoal texture, then reapplied oil and layered epoxy until black ring looked like it belonged (can't do that with any other surface I can think of?). After 15 years there is no sight of the insidious black mould from water penetration so I suppose it is the same recipe as with most thing successful projects in life, research, research, preparation, preparation, preparation and don't falter at the finish line.

My thoughts. Firstly, as has been said, you'll get better results seeking professional help, especially for such an unusual design. The external surfaces are an expensive part of a build. The larger the external surface area per sqm of footprint, the larger the cost per sqm. Seperate wings & courtyards increase the external surface area greatly. This plan has a very large external surface area, so will be costly per sqm, for what is already a very large dwelling. Separate wings also increases hallways & circulation space, which some people find wasteful, & increase the time to move from one part of the house to another. Instead of a U-shaped house, how about an L-shaped house? This would reduce the external surface area of the build & the amount of hallway space, reducing the cost per sqm & the size of the dwelling. With an L-shaped home most rooms could face the outdoor space in the NE side of the block, but some (possibly the minor bedrooms) would likely face the southern street. So, a couple of questions; Is this a newly developed or established area of Sydney? If it's an establish area with neighbours close by, could you post a screenshot of a Google Maps satellite image, to get an idea of outlooks & whether there will be privacy issues with neighbours? How quiet is the southern street? Are you happy to have rooms facing this street? How much busier is the western street? Is it possible to locate the garage facing the western street, or is it too busy for access? I'd much rather have the garage face a noisy street than the master bedroom (although the ensuite will help a bit). Also the western side of a dwelling is a great place to locate a garage, as it shields the house from the hot afternoon sun. The west is not a good place for bedrooms (although again, the ensuite will help). On that note, have a read of this, paying attention to the section on passive design & orientation. http://yourhome.gov.au/passive-design/orientation As for your current design, your bedroom wings are likely to shade your living areas for much of the day in winter. A skillion roof with north facing clerestory windows, as shown in a few of the pictures in this thread, would help get winter sunshine to your living areas. Although an L-shaped build would allow more northern light to the living areas than the current U-shaped plan. Best of luck with the build.

i put the bathroom next to the master to have the bathroom door off the short hallway rather than opening into the retreat and if you draw a line across the floor in your original plans to make a path where you will walk and leave space for furniture you will see that despite the size of the retreat it was just like a big hallway with no where for comfortable furniture arrangements and i would double check with the Solar panel supplier to confirm the ideal roof angle... double glazed windows (or thermal break double glazed are better but much more expensive) but windows can't exclude the worst of the summer heat without external window coverings and big areas of east and west glass will impact your compulsory BASIX ratings and playpens and baby gates across the top and bottom of the stairs makes everyone safer and also useful to keep small kids out of open plan kitchens