There are so many options today on flooring. Engineered timber products, bamboo, solid timber overlay, timber look tiles... What is important to know first is what you are laying over, how solid is it, how level is it, how even is it? Given that you have a number of different top finishes, it sounds like you may have different sub floor structures. Whatever you go for will be determined by how stable the substrate is and what structures you are laying over.

the original ensuite configuration is excellent but this alternative provides 50cm extra storage wall in the wiw and a view of the vanity as you walk into the ensuite...i've also swopped the study and family bathroom to create the extra width for the entry and to keep all the plumbing (including downstairs) closer together and included an idea for the family bathroom that creates a multi person facility that is more private from the hallway btw moving the laundry downstairs removed the storage area for the garage so that lost space has been added back to the garage

Depends on budget. Many dwellings (probably majority actually) don't setdown the floor structure to end up with a flat floor throughout. It costs extra money to achieve for something that is to most people un-noticable. High quality dwellings do this all the time however. If you're going to that level of detail you should also look at setting down the floor edge where the sliding/stacking/bifold doors are (if you have them) so that the door sill is flush. This something you'll see continuously more often than the bathroom/ens floors. It was mentioned on 'The Block' recently and I've now had numerous clients asking about it and/or presuming that this how all floors are done.

thank you for all of your comments. The main issue is that this wall faces quite a steep hill, so if I excavate too much I run the risk of creating a 'pool' under a suspended floor, facing the hill. This would be a disaster for the old double-brick home, which already has damp problems from water from the hill. My other concern about a slab is creating a permanent damp patch next to the house, assuming the black plastic membrane under a slab would be permanently damp (no evaporation). The mortar throughout the original house is lime mortar which is highly permeable and turns to dust when permanently damp John Cameron, I appreciate you mentioning passive solar, I'm familiar with this. Would it be best in this case to put rigid foam (say 50mm) under the actual slab before casting it? There will still be a thermal bridge at the perimeters though. MB Design I like the idea of a graded slope under a suspended timber floor, so will check with a structural engineer as to 150->400 allowance, noting my comment above about not wanting to pond water Two's Company I like the idea of a cement sheet for the wet room area - I have actually done a bathroom like this before and it works with great waterproofing. TBH I'm wondering right now if I should just redesign the whole thing. I'm going to make another post to canvas opinions on the two options and costs. Thank you! Sue