Hi Chris The cheapest option is Grind & Seal, but we usually recommend Mechanically Polished Concrete for inside of a home. This is by far a better option, if you were to go for a Matte or Satin finish it is less expensive than a higher gloss finish. Mechanically Polished Concrete does not have a top coat sealer requiring drying and curing time and does not need re-applying in the future which will save time and money in the long run. Because Polished Concrete does not require drying or curing time it can be used as soon as the process is completed unlike the Grind & Seal option. All floors are slippery when wet, a non slip agent can be added to a top coat sealer which would be the Grind & Seal method which we do apply in a shower area if there is not a shower base. Polished Concrete in Matte and Satin finish does have a very good slip rating, has no grout lines as with tiled floors where dust can get trapped therefore it is a wonderful easy to clean flooring solution. Hope this helps, I have provided some details regarding the 2 main processes below There are 2 different finishing processes / methods that are commonly called Polished Concrete, they are very different so it is important that you know the difference & which process/method you want and which is being used on your concrete Polished Concrete - 12 to 17+ step process During this process the concrete is ground to the desired level of stone exposure. After grinding the concrete surface, the Polished Concrete process begins. This process has a densifier applied in multiple stages that is absorbed into the concrete which hardens and strengthens the concrete. A Polished Concrete Floor is Polished in Multiple stages in a Refining Process using diamond tooling & resin pads. A penetrating sealer is applied in the final buffing stage to complete the process The "Polished Concrete" process has "NO TOP COAT SEALER" applied therefore there is no drying or curing time required so your space can be used as soon as the process is completed Grind & Seal (a 3 to 4 step process) This is NOT Polished Concrete. Grind & Seal is often referred to as Polished Concrete, this is the cheaper substitute that gives a "Polished Concrete Look" With the Grind & Seal method the concrete is ground to the desired level of stone exposure and a TOP Coat Sealer is applied such as water based, solvent based, urethane, acrylic or epoxy requiring 5-7 days to dry & cure

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