How do I know if my deck board is rotting, or just wet?
A deck board that stays soft or spongy after several dry days — not just after rain — has wood rot, not just surface moisture. The screwdriver test settles it in under a minute.
Likely causes, ranked by probability
- Test it — the screwdriver check: Press a flathead screwdriver into the board with moderate pressure. Sound wood resists; rotted wood gives way easily or the screwdriver sinks in. Check several spots, especially near the edges, seams, and anywhere water tends to pool.
- Most common location — near ledger boards and joints: Central Florida's humidity and repeated wet/dry cycles concentrate rot where water lingers longest: the ledger board where the deck meets the house, board ends, and around fastener holes.
- A pattern to watch — rot spreading from one board to its neighbors: Rot rarely stays isolated once it starts, because the moisture source (a gap, a low spot, a failed sealant joint) keeps feeding the same area. One soft board is a repair; several soft boards in a line is usually a joist or ledger problem underneath.
What you can safely check yourself
Test with a screwdriver on a dry day, not right after rain — wet-but-sound wood can feel slightly soft on the surface even when the core is fine.
When this needs a licensed tradesperson instead
Replacing individual rotted boards is handyman scope. If the rot has reached the ledger board, joists, or support posts, or the deck is more than a couple of feet off grade, that structural work is worth a closer look before anyone stands on it — and post/structural repair may itself need a City of Mount Dora permit.