Internal Wall Insulation

[sbx3]

I am rebuilding our ensuite following a leaky shower issue a while back. We decided to rip everything out and start from scratch.

The house was built around 2005. It’s standard construction with brick and cavity wall, which as far as I can tell is filled with yellow wool insulation.

I plan on battening the external wall to make it easier to fit tile backer boards. I feel I will personally achieve a better result than using the dot and dab method. My question is whether we need to insulate between the tile backer boards and the wall?

Before it was just dot and dab plasterboard with no insulation.

Two of the walls are back to the grey brick but its only one that is external. The other is a party wall.

Thanks for your help.

 

[SFK]

I would say yes. My (as a DIYer) only putting 25mm of PIR on outside wall of bathroom significantly reduced condensation on tiles. I used 25mm x25mm wood from Wickes, frame screwed into wall (8mm masonry drill bit through wood and into wall and hammer them in). Used frame spacers to ensure all the wood was flat and level with each other
Then filled space between with PIR. And taped it all up with aluminium tape. The screwed backer boards onto the wood. And tiled.

 

[sbx3]

I would say yes. My (as a DIYer) only putting 25mm of PIR on outside wall of bathroom significantly reduced condensation on tiles. I used 25mm x25mm wood from Wickes, frame screwed into wall (8mm masonry drill bit through wood and into wall and hammer them in). Used frame spacers to ensure all the wood was flat and level with each other
Then filled space between with PIR. And taped it all up with aluminium tape. The screwed backer boards onto the wood. And tiled.

Thanks. Should there be any gap left between the PIR and the wall or the PIR and the tile backer board?