These tradies are cowboys . I have never seen a mess like that in a bath or else where in over 30 years . The bath normally sits on a bed of concrete slurry or if it is a cast iron bath it should be supported by either feet or the hob. The bath should have enough room under the edges to allow the tiles to go under the lip so a proper silicon seal can be applied all the way around the lip of the bath. As for the insulation it is not necessary to have it wrapped in any water proof protection. If the water is getting onto the insulation then you have bigger problems and from the look of the photos this looks like a definite future possibility.I like to put insulation batts all the way around the bath to try to retain the water temperature for as long as possible,not many people do this though ,but the more you insulate things the better. Looking at your photos the pipework connecting the waste is broken off so the hob will need to have atleast one side pulled off or an access hole cut into it to connect the plumbing. I would be getting these plumbers and builders checked out,if the photos are any indication to go by then there would be other areas of faulty workmanship for sure, -sorry to tell you.

sounds like you need a drainage and waterproofing expert and i wouldn't be adding anything extra to the floor until the flooding problem is resolved

Hi Geraldine Your enquiry to waterproof the underside of your balcony is one we receive a lot of. We build balconies, patios etc and line the undersides of such structures. From our experience in doing this for 25 years, we don't know of any system put into an existing structure that can be guaranteed 100% waterproof by the manufacturer of the product or the installer. I could be wrong however I'm sure there will be a disclaimer in your quote. We have used the NexGen system with success in a Cottesloe balcony (WA) and used a different system in Mullallo and Peppermint Grove (WA) within 4 years of each other. With the Mullaloo balcony, we've had no issue after 4 years of install however the Peppermint Gove balcony waterproofing system installed in Janaury 2021, approved by the engineer, had to be cut on a two unusual angles to meet the 300 mm beam. With the first down pour, it did leak and we returned twice to rectify the problem with installing additional flashings (covering the beautiful Merbau beam). It may be a case of starting over with removing the existing decking boards to install the waterproofing membrane and installing new decking boards on new framing, keeping in mind this will raise the existing floor level. The other consideration is that this is not a straight edge balcony so whatever waterproofing system is used has to be cut on a curve which may compromise the integrity of the membrane. You'll require a gutter and down pipes on the front of the structure also. Whatever you decide to do, make sure you engage with a company who knows what to do. Best wishes! Castlegate Home Improvements

"Builder says as long as shower area is waterproofed correctly this is not an issue as their warranty covers any waterproofing issues in future." Which warranty exactly? Do you have anything in writing? A 'warranty' sounds useful but you need to read the fine print and know what they cover and what exemptions benefit the builder. Then there is what is said and what is done. After you have made your last payment getting a builder to come back to rectify something is a lot harder. They might avoid saying outright that they won't fix it but they can never find the time to do it. Then you're into talking to lawyers territory. Then there's the reluctance to spend their time and money redoing anything they overlooked or took shortcuts with. It's much easier for them to tell you that you don't need something than to redo it properly. It will probably be alright for a while and by the time you find it isn't, see previous paragraph.