You should ask your builder why he is reluctant about 3 metres ceiling heights on the upper level. It is more work for him, so he should quote appropriately, and be paid for the extra height, the extra materials, the extra scaffolding etc. If you are building as an investment you need to understand your market. Will people pay extra for the extra high ceilings so it is profitable for you? In some really expensive areas homes with ceilings less than 3metres are looked down on by the buying public. In poorer areas people are more interested in square metres of floor area than ceiling height so you would lose money by putting in 3m ceilings to both floors. When building townhouses you need to think with your head, and not with your heart. Everybody loves high ceilings, but make sure that you increase the door and window heights proportionally. Standard height doors look funny with 3m high ceilings. This is one of the reasons why 3 metre high ceilings do cost so much more as you need everything taller, including window furnishings for it to look right. If you are building townhouses for future rental you will need to outweigh the additional cost of the extra height with the small increase in rent that could be achieved. While you say the height limit is 11 metres, it probably isn't 11 metres when it is close to the side boundary. Many townhouses are built close to the side boundary so you should check with your council about the side setback requirements. Usually the taller the building the further it has to be from the side boundary. Best of luck Dr Retro of Dr Retro House Calls and Dr Retro Virtual Visits

i'm guessing that a problem could be that the boards will shrink and create drafty gaps so i think my old builder dad would have laid the boards upside down, without nails to settle to the temperature and moisture in the room while he did other jobs for a week or two and then turned over the boards and, using a solid timber length to push the boards tight as possible before nailing and he would have probably appreciated the idea of adding some under floor insulation as well

electric underfloor heating is great for bathrooms (and laundry, mudrooms, entry and hallways when it needs to be left on for weeks at a time and not much good for a ten minute shower) and is preferable to anything visible like hydronic heaters that take up wall space but your voids will suck most of the heat upstairs ..our reverse cycle AC has been much more economical to run than the whole floor electric slab heating that we had in our previous house (supplemented with a wood burner and gas log fire in our cold climate) but we made sure that the void over the stairs was able to be blocked off to zone heat downstairs with separate heating upstairs but having lived in different areas of Sydney i'm wondering why a new built well designed house with great insulation would need more than modest supplementary heating that can be more economically provided with AC

Every month seems to bring new flooring products to market that claim to be water resistant or waterproof. But how do you know which products are suitable for wet areas in your home? And what rooms are considered wet areas? Selecting the Best Flooring for Kitchens, Laundries & Wet Areas Which types of flooring are suitable for use in wet areas? So long as your floors are properly waterproofed in accordance with the NCC, Flooring 2 You’s range of Hybrid flooring is suitable for installation in bathrooms, laundries and toilets in domestic homes without floor wastes (Not to be installed within the shower or near a drain). Our hybrid flooring is completely unaffected by moisture, and 100% stable when exposed to topical moisture on a regular basis. Hybrid planks are composed by creating layers that are resistant to water and scratch-proof that are made to last: The top layer is treated to make them stain and scratch proof. A decorative layer gives it the look of timber. The rigid core is innovative that provides stability, especially against changes in temperature and water, including heating that’s underfloor and windows that are north-facing. The last layer is the acoustic backing that helps with noise reduction. When it comes to other areas of the home, other products are also suitable provided the proper maintenance precautions are taken. For more product specifications, care and maintenance information, please refer to the respective product pages. https://flooring2you.com.au/selecting-the-best-flooring-for-kitchens-laundries-wet-areas/