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.

a friendly call to the builder to let him know that everything else is great but there are a few tiles that need fixing (and any other faults) and ask when he thinks the tiler could come and fix them...hopefully he'll respond positively and the problem will be resolved but, immediately after the call send an email confirming what he said and when he said that the tiler would be coming and follow up within the stated time to ask if there's a problem and why can't they fix it to save the bother of getting involved with his insurance company (details should be included in your original contract) hopefully you'll be successful and the tiler will come in between other jobs and do the repair...in the meantime check every single tile (in case there are other hollow ones) and draw a map to identify every suspect tile so that you can check that they're all fixed and, do you have any spare tiles?...have them ready for the tiler or try and identify the tile in case you need to replace any that get broken...only other option is to contact the insurance company and tell them about the builder's response and if all else fails it should be a cheap small job for another tiler and/or you could have a go at fixing them yourself but ask the builder first if he values his reputation and his no claim bonus he'll respond positively

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

It would be such a shame to rip up your beautiful floors, to try and do polished concrete now would be such a hard and costly job, along with the mess and the uncertainty of getting a good job that you may not like on completion as suggested, why not embrace your floors, decorate with the industrial look that you love , maybe a brick or concrete look wall could look really stylish and cost a lot less in $’s and stress