That looks a nice job! The reason i was going with ply vs a concrete base was also due to the fact that i was making it wider than the original base. For me i still want the tile level to finish flush with the carpet so i just need to work out what size base i need for the 20x20cm 6.5mm thick tiles to sit on to line up with the carpet (prob 18-20mm total thickness) And looks like i dont necessarily need a word trim edge now 🙂