There is no specific regulation but it would not be recommended behind a gas cook top. If there is a concern you could install the timber behind a glass splash back for protection. There is also a really nice tile that looks exactly like timber as another option.

I think it would depend on the layout of the room and position of door and window and also possibly how bold or dark the feature tiles are. Do you have a photo or a plan?

The size of floor tile: 300 x 300 mm and the size of wall tile: 300 x 600mm The floor tile and wall tile do not align at all. It looks unprofessional. Should the tiler redo the job? Thanks for your advice.

Thank you, gurus oklouise and siriuskey. Your knowledge and ideas are invaluable. oklouise, I could live with 1700 x 450 vanity and storage opening from inside toilet room. It would just mean I'd have to sell the marble basins I purchased months ago and find smaller basins. Not really a major problem if it achieves the end goal! siriuskey, I did consider this arrangement (but with the shower the existing width), and would certainly be an improvement on the existing layout, but I really prefer the toilet being separate. If I stick with this arrangement, I'd have to at least lengthen and raise the height of the small privacy wall. The impact of moving the door on the adjoining room isn't significant. It just means I have to rearrange furniute in a way that isn't quite as appealing. I think it will come down to comparative costs. I know the alcove arrangement will be a lot more expensive, but I do like it much better so it will depend how much more expensive. Leaving as is and moving the door will still require major work to the floor in the shower area, but narrowing and lengthening the shower will achieve my major objective of eliminating all the glass. (Odd how you can get tied up and miss the obvious when planning! I hadn't considered the benefit of narrowing the shower while lengthening. That does make a big difference!) At least I've now narrowed it down to two options so I can proceed to get some cost estimates. Thanks again.