T
TheTiler
It was over-boarded with plywood - not a floating floor either as it was sat on joists. I did a very similar job for a police officer around 5 years ago. No blue sirens asking for a repair yet. I'd just pick an adhesive manufacturer, phone their technical helpline and follow their rules for prep/expansion joints etc. and mix everything in exact quantities. Then the ball is in their court if anything goes wrong.