Where does rot start on a New Brunswick deck?

Rot almost always starts in the same three places on a New Brunswick deck: the ledger board connection, the post bases, and any horizontal surface where water pools and sits.

Understanding where rot originates — and why — is the key to catching it early and making your deck last decades instead of years. NB's Maritime climate is particularly brutal in this regard. You're dealing with 100+ freeze-thaw cycles per year, heavy snowfall that sits and melts slowly, and persistent humidity that keeps wood damp for weeks at a time. That combination creates ideal conditions for wood-destroying fungi to take hold.

The ledger board is the single most common rot origin point. This is the board bolted to your house where the deck attaches. When flashing is missing, improperly installed, or has failed over time, water runs behind the ledger and gets trapped between the wood and your house's rim joist. It can't dry out, so it stays wet for months. By the time you notice soft wood or discolouration, the rot has often already spread into the house framing — which turns a deck repair into a much more expensive structural repair. Always check this area annually by probing the ledger wood with a screwdriver. Solid wood resists; rotted wood gives.

Post bases are the second major trouble spot. Any post sitting in or near soil is at risk, but the real danger zone is where the post meets the concrete footing or the metal post base. Water collects at that joint, wood stays wet, and end grain (which absorbs moisture like a sponge) is right there exposed. Posts buried directly in concrete are especially vulnerable — the concrete holds moisture against the wood with no way to drain or dry. Modern best practice is to use adjustable post bases that hold the post slightly above the concrete, allowing airflow and drainage underneath.

Horizontal surfaces and trapped debris are the third culprit. Anywhere water pools rather than sheds — the tops of beams, the tops of posts, anywhere leaves and debris pack against wood — rot follows. Beam tops that sit under decking boards and never see sunlight are particularly vulnerable in NB because they stay damp through our long springs and wet autumns.

Practical things to check every spring:

Probe all ledger board wood and the rim joist behind it with a screwdriver. Inspect post bases for soft spots, especially at ground level. Clear any debris packed between decking boards — that trapped moisture accelerates surface rot. Check the underside of your deck for any dark staining or soft joists, particularly near the house end. And look at your flashing — if it's pulling away from the house wall or missing entirely, address it before the next rainy season.

When to call a professional: Surface rot on a few decking boards is a manageable DIY repair. But if you find rot in the ledger, rim joist, posts, or structural beams, stop and call a deck contractor. Structural rot is a safety issue, and improperly repaired ledger connections are one of the leading causes of deck collapse. A professional can also assess whether rot has spread into your house framing — something that's easy to miss without knowing what to look for.

If you're unsure about the condition of your deck's structure, New Brunswick Decks can match you with a local contractor for an inspection and free estimate.