DIY Bathroom renovation , looking for a check on my methods

[destix]

Hi , I've been lurking and reading the very helpful information on this site , helping with my bathroom renovation.
But I thought I would put my planned methods here to see if anyone wants to give an opinion on it.

Started a re-grout of my bathroom which is from the previous owners and was a mess with grout over the tiles etc, and bought a multitool to rake the grout out

That hasn't gone so well and has turned into a full strip out lol , as some of the tiles came off and I wasn't happy with how well the existing tiles were fixed (tubbed addy)

Anyway I've bought new 600x300 porcelain tiles for the walls , and 12mm hardiebacker to replace the plasterboard on the walls
One wall is the outer wall and is rendered/plastered , with a window in the middle
should I strip that back to the block and fix hardiebacker with adhesive and wall plugs/screws?

Also the floor is 18mm chipboard and is in good condition , I may however cut a trap below the radiator to alter the pipes for a new towel radiator , which I will probably repair with 18mm ply
should I then just fix 6mm hardi over the top and tile?
I haven't decided on tiles for the floor , but possibly a galaxy granite or quartz

Would also appreciate recommendations on adhesive to use , bearing in mind I have no trade account , although I may try to spoof a topps account as I'm an electrician

Thanks for any help
Mark

 

[White Room]

That is some first fix time. 18 months!

Bugger, I didn't think my maths was that bad

 

[destix]

That is some first fix time. 18 months!

I hang my head in shame, it's actually been about 2 years!

All I can offer are half hearted excuses
Might get it done for Xmas now the walls are done.

If I overboard with hardiebacker then tile, should I use an elastomeric adhesive, an S2 or just standard flexi?
Thanks

 

[macten]

Standard flexi is what I use but you can even use a non flexi. The adhesive is there just to fill voids, it's the screws that provide the mechanical anchor.

 

[SJPurdy]

Standard flexi is what I use but you can even use a non flexi. The adhesive is there just to fill voids, it's the screws that provide the mechanical anchor.

Macten's answer is for the adhesive underneath the Hardie boards.
To stick the porcelain tiles down on top of the Hardie board then use a flexi adhesive.
The overboarded floor must be rigid and free from deflection before tiling.