Are you able to install a window on that back wall where the washer is at the moment? I know you said there is a hot water unit on the other side, but if its to one side of the wall and not in the middle, maybe you could install a window on that wall which will bring light into the room. Also I would change the washer and put in the corner of back wall and the external wall, so its facing the sliding door, this will allow you to put cabinets in a sort of L shape and install the laundry sink next to the washer on that back wall. This will give you cabinets all along the other wall, extra space and storage. The external doors you can make them open outwards and all the way back against the wall, all you need is the right hinges. So when you speak to your carpenter let them know that you would like it to open outward completely and up against your external wall. I would also swap the door, so that the hinges are on the other side, so as you open the door outwards it will open to your right as you're looking at the picture and up against the wall not the bathroom window.

In Victoria a lot of double garages for townhouses are only 5500mm wide, so 6180mm wide is generous. Why don't you go to an empty carpark on the weekend with your cars, a measuring tape and some chalk and test it? It also depends on the age of your household - strapping a toddler into a toddler seat often means that the car door needs to be fully open, and the same with babies and baby seats. Getting a tired and grumpy toddler into a car seat can be like wrestling an octopus. So if your household has plans for babies or toddlers in the future I would probably go for the wider garage now as it will be less stress in the future. Best of luck, Dr Retro of Dr Retro House Calls.

At least the Crimsafe doors won't take from any design features. What I will throw into the discussion is that you could put your screen door further out in the Entrance area (there seems to be half a metre or so in the photograph) and if they were double frames could latch back when required, rather than one large frame taking up all the space. Just ensure the area is covered, so visitors son't cop a deluge awaiting access. For added security, bolts could be attached to one side top and base and the other frame do most of the swinging.

What performance is more applicable for your climate? Double glazing will perform significantly better than single glazed whatever in regards to heat loss. You can't beat the air gap factor if you're trying to keep avoid heat loss. Yes there are "Low E" single glazed products such as viridian Comfort Plus which depending upon which side of the glass the absorption coating is placed it will perform in different ways, but bear in mind that since it also will reduce heat gain in winter it can actually work against passive solar building performance if not properly applied. In other words, it's not a "cheap" replacement for double glazing. In Victoria, we generally spec standard double glazing and use external controls such as blinds to mitigate heat gain issues in summer. Thermal Performance Specialists such as an Energy Raters understand the technical nitty gritty around this issue the best, and always good to seek their expert advice when applicable.