Borer damage

🛠️ Borer Damage Found Under a NZ Home – A Real-World Example

Posted by Alex | Book a Builder NZ | www.bookabuilder.co.nz

Date: 09/09/2025

While inspecting under a home this week, I uncovered an infestation of borer— not just in the floor joists, but also affecting key structural components like the bearers, piles, and even a brace that had completely detached at one end due to the severity of the infestation.

📸 What We Found

This isn’t just cosmetic damage. When borer affects structural elements like bearers, piles, and braces, it compromises the stability and safety of the entire home.

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🐛 What Is Borer and Why Should You Worry?

Borer (commonly the Anobium punctatum in NZ) is the larval stage of a beetle that bores into timber, silently eating away from the inside for years. By the time the exit holes and frass (fine sawdust) appear, the damage is usually already done.

In this case, the infestation had progressed far enough that a structural brace meant to stabilise part of the floor framing had completely let go — a potential safety hazard, especially in areas prone to ground movement or earthquakes.

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⚠️ Why Subfloor Areas Are High-Risk

The subfloor space under homes often has the perfect conditions for borer:

Poor ventilation

Damp or untreated timber

Limited visibility and access, so problems go undetected

This is why regular inspections are essential, especially in older homes built with untreated native timbers.

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✅ What Can You Do?

If you're a homeowner, here are the key actions to take:

1. Inspect: Look for small round holes in timber, fine dust (frass), and signs of soft or crumbling wood.

2. Ventilate: Improve airflow under your home to reduce moisture and deter pests.

3. Treat or Replace: Affected timber should be treated with a professional-grade insecticide, or replaced if it's structurally compromised.

4. Call in the Experts: If you find anything suspicious, don’t delay. Get a professional opinion before the damage spreads.

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🔨 Need a Hand?

At Book a Builder NZ, we’re here to help. Whether it’s a routine inspection, timber treatment, or structural repair, we connect you with trusted, local builders who know what to look for — and how to fix it properly.

👉 Contact us here t

o book an inspection or get a quote.

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Stay safe,

Alex

Book a Builder NZ

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💡 Bonus Tip:

If your home was built before the 1950s and has never had borer treatment, now’s the time to check — even if you haven’t seen visible signs. It could be quietly eating away underneath.