To quote Missy Elliott, I'd flip it and reverse it! ; D Contrary to some others, it sounds like a great block, with a north-facing rear, and 14m width is great to work with! I also live in Melbourne and my previous home's rear faced north. Although small (only 4m wide), it was such a beautiful home to live in as our living area at the rear had trifold doors and was flooded in sunlight through Winter (lovely and we rarely used the heater during th day) and in summer was bright but not blinding or too hot at any time of the day. Conversely the bedrooms at the front were lovely, dark and cool through the year. So when looking to buy our current home, a north-facing rear was literally top of my priority list, my family thought I was mad! So ensure you use the opportunity for a lovely, light-filled home to live in and to save on heating and cooling. I would put your living at the rear where the current bedrooms are, with windows/doors right along the northern (back wall), kitchen where the rear bathroom etc are, and dining further along the eastern wall adjacent to that. I also don't like the glare of a western dining room late in the day as the sun is low in the sky when you're typically having dinner. Furthermore, it's lovely having the (eastern) morning sun streaming in a kitchen and where you're having your breakfast in the morning! Alternatively, stretch your Kitchen, Dining, Living across the full width of the house at the back, I think it's almost 11m wide, which is a comfortable width to arrange that, with windows across the back, and trees at any side windows on the west. Finally, I'd flip the garage and master bedroom, so your bedroom isn't on the hottest side of the house going into the evening. Put rooms you spend a brief amount of time in on that side - bathrooms, laundry etc. As for the alfresco area that seems so popular on new builds, I'm not a fan of them in Melbourne at all. They merely block the valuable sunlight from entering, brightening and warming the house, and I'm sure they don't get used that much anyway. If you need the covered shelter, then it's likely too cold to sit outside anyway, you're better off to have it uncovered, or have a retractable awning or umbrellas for nice days when you would sit outside. And having this on your western side will only make the dining area shaded until the very late (& hot) time of day when you'll be blinded by the setting sun (unless you have neighbours on that side which shadows the afternoon light anyway). As for mould etc, just ensure you have good ventilation, good sub-floor drainage etc, I don't imagine it should be a problem usually. So glad you're considering aspect though, I see so many project homes that don't take the aspect of the home into consideration at all. With some moving around, you could have a lovely home ahead of you.

And looking again, the rather narrow family room may be a bit hard to furnish, with doors on two sides and missing wall. It seems small compared to dining room and the internal playroom area. It’s the best spot in the house, north facing with views to your garden so you don’t want it to end up as a virtual corridor. Corners are the prime real estate. At the moment they are bedroom 1, bedroom 5, garage and alfresco. Three of those aren’t areas that need an outlook. I’d love to see your sitting area in a corner room with windows on two sides and views of your soon to be delightful garden! Perhaps alfresco where bed five is . Lounge where alfresco is, with double doors to close it off if needed, and maybe bed five where lounge is. I can’t see the plan as I write on my phone so I may be missing something major! Best of luck.

Putting roof lights in a Perth house (indeed most Australian houses) creates the potential for unwanted heat gain, so they are generally best not facing north. Even high performance ones such as Velux which are really designed with European and North American climates in mind. Aussie sunshine delivers about 1000 Watts per square metre of radiant heat for much of the day. We usually don't need a multi-kilowatt roof heater in our homes... South light is indirect, which avoids pools of sunshine creating potential glare, but still about 70% as bright as north light, with way less heat gain potential. Polishing concrete can be a bit of a lottery. I have seen many examples where the owner is disappointed with the outcome. A safer bet might be to use large format rectified edge concrete-look ceramic tiles? At least you will be sure of what the finished product will look like. Maybe do a cost comparison between the two. Unless the concrete polishing is a DIY effort, you might be surprised at the cost of getting it done. An insulated edge slab on ground should not be cold under foot in Perth, particularly with your fireplace taking the edge off in winter.

the second plan is probably closer to your ideal but with east setback narrower there would be more space inside and/or the extra 50cm x 28m of garden is available to combine with the other side or in the rear garden but i think you've added extra to the garage to make a drive through access to the rear but how would you use all that garden space on the western side??..so many options and best orientation and use of the available space will almost always be better achieved with a custom build although there's probably a builders' plan that is closer to ideal with only relatively minor changes but initial suggestion could have more useable space inside and out