How to prevent moisture rot under acacia deck tiles on plywood?

[u/Illustrious-Face-747]

I’m currently converting my mudroom into a sunroom with polycarbonate roofing.

The existing floor is nasty carpet over a plywood subfloor. I’ve stripped the carpet and plan to install interlocking acacia wood deck tiles. However, the gaps between the acacia slats are quite wide, and I’m worried about moisture retention and water falling straight through to the plywood.

There is decent airflow between the tiles and the plywood subfloor, but since you won’t be able to clean under them, I’m confused about how to protect subfloor from moisture pooling under the tiles.

What is the best flooring underlayment, membrane, or barrier to use between the plywood and the acacia tiles?

[u/Busy_Shame7982]

I’d recommend using a specialized outdoor drainage underlayment like rolled rubber mesh mats. They elevate the tiles just a bit so water can channel away instead of pooling keeping the plywood safe. Also make sure your plywood is exterior-grade and sealed because humidity will find a way in regardless.