Bathroom Subfloor That was Tiled and Remaining Tile Adhesive Help, advice, information, answers and tips on all types of flooring from laminate and carpet to timber and vinyl

[J-S-Q]

I am refurbing a bathroom and it has a T&G chipboard floor, nailed onto joists. It was previously tiled and had underfloor heating but I have now stripped this. My plan is to install Warmup DCM-Pro underfloor heating, with 100mm Warmup insulation boards and then tile on top.

There is a certain amount of tile adhesive residue left from the old installation so the surface is a little uneven. I guess it has some bumps of 2-3mm. There are also a few small punctures in the flooring (See photos). What is my best way forward? I see two options:

a) Repair the holes somehow and possibly apply self-leveling compound.
b) Rip up the chipboard and replace with plywood.