Pulled out some old hardwood floor in a closet to convert to a bathroom. Beneath what was wood laid diagonally. Over that, I placed 3/4 particleboard.... yeah, I meant to buy plywood, but the store was out of stock and didn't realize this was a significant mistake. Over that, I screwed in 1/4 hardibacker, no thinset beneath.

I've done some reading that particleboard and tile is a no no do to flex. However, shouldn't the solid floor beneath the particleboard provide durability?

At this point, the tile is already down. I guess I just need to wait and see what happens. Thankfully, its a tiny bathroom, so replacing the floor would be a weekend job.

Unfortunately my toilet tank leaked and the floor beneath the particleboard got wet. Strangely, it looks like the particleboard is dry except for right around the toilet flange. Think I'm hosed or might the floor actually hold up?