Rusting Joist Hangers

Rusted Joist Hangers on a Deck – Why It Matters (and What I Found This Week)

This week I inspected a home where several of the deck joist hangers had completely rusted out. The photo above shows one of the worst examples — the metal hanger has corroded to the point that it’s no longer doing its job, and the timber around it was also starting to deteriorate.

Joist hangers are the brackets that hold deck joists in place. They’re a critical structural component because they support the load of the decking and anyone standing on it. When these brackets rust, weaken, or fail, the risk isn’t just cosmetic — it can lead to significant structural movement or even partial deck collapse.

Why Do Joist Hangers Rust?

There are a few common reasons I see this happening:

Moisture exposure: Decks are constantly exposed to rain and damp air. If the metal isn’t galvanised to the correct standard or if water is allowed to sit around the hanger, corrosion can set in.

Poor maintenance: Leaves, soil or debris piled up against the timber and brackets can trap moisture, accelerating rust.

Incompatible fixings: Using the wrong types of nails or screws can cause galvanic corrosion.

Age: Older decks often used lighter coatings or hardware that doesn’t meet modern durability standards.

What Are the Risks?

When joist hangers look like the one in the photo:

The joist may no longer be properly supported.

The deck could sag or bounce when walked on.

In serious cases, parts of the deck can detach from the main structure.

Rot can spread into the joists or bearer, creating a much bigger repair job.

What Should Be Done?

If rusted or weakened hangers are found, the recommended steps are:

1. Replace all affected hangers with the correct hot-dip galvanised or stainless-steel brackets (depending on the exposure zone).

2. Check the surrounding timber — if it’s soft, cracked or decayed, it may need repair or replacement.

3. Use proper fixings to prevent future corrosion.

4. Improve drainage and ventilation under the deck to stop moisture build-up.

5. Consider a full deck assessment if multiple hangers are rusted — there are often other issues hiding underneath.

Why Inspections Matter

Deck issues like this are rarely visible from above. What looks like a tidy, well-maintained deck can be structurally compromised underneath. This is why pre-purchase inspections — and regular property checks — are so important.

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