How much does it cost to replace rotted deck joists in Moncton NB?

Replacing rotted deck joists in Moncton typically costs $2,000–$5,000 for most residential decks, though the final number depends heavily on how many joists are affected and what else the inspector finds once the decking boards come up.

Joist replacement is considered structural repair work, which means it's not a simple weekend DIY project. A contractor will need to temporarily support the deck, remove the decking surface boards, sister or fully replace the damaged joists, and then reinstall everything properly. Labour is the biggest cost driver here — skilled framing work in the Moncton market runs $60–$100/hour, and a full joist replacement job on a typical 12x16 deck can take 2–3 days with a two-person crew.

Material costs add up quickly too. Pressure-treated lumber for joists (you'll want UC4A-rated where there's any proximity to moisture) runs $3–$8 per linear foot depending on size. A standard 12x16 deck might have 10–14 joists at 12 feet long — so even before labour, you're looking at $400–$900 just in framing lumber. If the ledger board is also rotted (very common — it's usually what causes joist rot in the first place), add another $300–$800 to replace and properly flash it.

Why Moncton Decks Rot Faster Than You'd Expect

Moncton's Maritime humidity is brutal on deck framing, especially joists that don't have good airflow underneath. The freeze-thaw cycle — Moncton sees 100+ freeze-thaw events per year — drives moisture deep into wood grain, and once rot starts in a joist, it spreads faster than most homeowners realize. The most common culprit is a missing or failed ledger flashing, which lets water pool right where the deck meets the house. If your joists are rotting, always have the ledger and rim joist inspected at the same time.

What Affects the Final Cost

The price can swing significantly based on a few factors. If only 2–3 joists need sistering (attaching a new joist alongside the damaged one), you might come in under $1,500. If the beam, posts, or ledger are also compromised, costs can push toward $5,000–$8,000. Decking boards that need to be removed and reinstalled (or replaced entirely) add another $1,500–$4,000 depending on material. Composite decking boards are harder to reinstall cleanly after removal, so factor that in if you have a composite surface.

A building permit may also be required for structural repairs in Moncton — check with the City of Moncton's building inspection department before work begins. It's a small cost ($100–$200) but skipping it can cause headaches if you sell the home.

Practical Next Steps

Get at least two or three quotes, and make sure each contractor is doing a proper inspection — not just eyeballing from the outside. Ask them specifically about the ledger board condition and whether the footings show any signs of heaving (Moncton's frost depth is 1.2 metres, and shallow footings can cause ongoing structural stress). Make sure any contractor you hire carries WorkSafeNB coverage and liability insurance before work starts.

New Brunswick Decks can match you with local Moncton deck contractors who handle structural repairs — it's a free service and a good way to get a few competitive quotes without the legwork. Reach out anytime to get matched.