Hi Wuff - house with no bath is not a problem. Your only issue may be at resale if a family with young children might be looking specifically for a bath but, unless you are planning to sell in the short term, that can't be a consideration. You need a bathroom that works for your needs now and in the future so if you don't need a bath and space is short, really do consider living without one. Good luck!

littleniffer, that downstairs rumpus has access to ZERO windows. It will be dark & cave-like. I doubt it would be legal as I think all habitable rooms must have access to external ventilation & light (I may be wrong). Wouldn't be pleasant in any case. Although I don't like internal wetrooms without windows, I'd probably prefer that than a cave-like rumpus. If you've got enough land I'd suggest stretching the build or as far as possible along the east-west axis, increasing the length of the north & south facing walls, while decreasing the east & west facing walls. This should reduce the excavation required. Though the main benefit (along with better passive solar design) would be if you can get away with downstairs being only one room deep, then all rooms will have windows. I'd have an open staircase, not closed, so light can pass between each tread. Unusually, I'd try to locate the stairs on the north side of the house, & have the flights facing north & south, to increase light to the downstairs area.

Is the brown area an accurate representation of the block area? If so it is quite likely you won't be allowed to build so close to you rear (western) boundary. In saying that it looks like the old dwelling was build close to the rear boundary, so I don't know. But I'd just say, speak to the council, or get in their website, & investigate your local planning constraints. Determine what the setbacks are, particularly the rear & side setbacks. I'd recommend reading the government's Your Home website, it's very good. This section on orientation is certainly recommended. http://yourhome.gov.au/passive-design/orientation To prevent overheating on summer afternoons & evenings w windows should be minimised. Any western windows should be shaded. Vertical shading is best for W & E windows, but the covered alfresco should offer shade to some of the western windows. I'd minimise other western windows. Northern sunshine is important for daylighting & passive solar heating. The northern window in the lounge room will get very good winter sunshine. So make sure it's a good size as this will be the window that warns your house in winter. Make sure it's shaded by appropriate length eaves (which will offer shade in summer, but not winter). If you wanted more light in the dining room & kitchen (& wanted to eliminate the western dining room window), you could introduce more northern sunlight with a split skillion roof design. Having north facing clerestory windows down the central spine of your build, with cathedral ceilings above the kitchen & dining room. It's good you've kept wetrooms in the original locations. This will minimise plumbing costs. The fact that they are all quite close together will reduce costs too. As oklouise mentioned, your local climate will determine what design elements are appropriate.

Hi Lorna Lux, I think there are some serious issues with the layout of your house. Both the living room at the front and the family and dining at the back have circulation needs that restricts furniture placement. I would be good for you to put your furniture into the spaces and see how you will need to move around it. A large amount of the circulation is wasting usable space and you are trying to fit a lot into a reasonably small house, which as Dr Retro mentions, makes the spaces quite pokey. For instance, if this is a tight urban site, which it appears to be restricted in width, why not look at bringing the entrance in part way down the side of the house which would allow much better use of the front room. You can still make a really great feature of your entry down the side and it is cheaper to create that space outside rather than give over precious floor space internally. I don't think it is ideal to enter either bedroom 1 or 2 directly off the family, dining and kitchen space. Do the occupants of bedroom 2 have walk past the dining and kitchen and up the hallway to use the shower or bath? A bit of a hike. I have worked on tight 10m wide sloping sites in inner city suburbs and there are good solutions that only take a bit of fine tuning to make them great spaces to live in. Good luck, Christine.