You can absolutely carry out a basic visual check of your home's piles yourself, and knowing what to look for could save you from a costly surprise down the track. That said, pile replacement is structural work that almost always requires a building consent and a Licensed Building Practitioner (LBP), so a professional assessment is an important next step if you spot any red flags.
What Are House Piles and Why Do They Matter?
House piles (also called stumps or foundation piles) are the vertical supports that hold your home off the ground. In New Zealand, older homes — particularly those built before the 1970s — commonly sit on timber piles, while newer builds may use concrete or steel. Piles transfer the weight of your home into the ground, so when they fail, you can end up with uneven floors, cracked walls, sticking doors, and in serious cases, structural instability.
NZ's damp climate, high humidity under many homes, and the presence of wood-boring insects like borer make timber piles particularly vulnerable to decay over time.
Signs You Can Look For Yourself
A careful homeowner can spot many early warning signs without specialist equipment. Here's what to check:
Inside the House
- Sloping or bouncy floors — place a marble or spirit level on the floor. If it rolls noticeably, the subfloor structure may be settling unevenly.
- Sticking doors and windows — frames that have racked out of square often indicate foundation movement.
- Cracks in walls or ceilings — diagonal cracks running from door or window corners can signal differential settlement.
- Gaps between skirting boards and the floor — a sign the floor has dropped in places.
Under the House
If you have safe crawl-space access, a torch and a flat-head screwdriver are your best tools:
- Probe the timber with your screwdriver. Sound timber is hard and resists penetration; soft, spongy, or crumbling wood indicates rot.
- Look for dark staining, fungal growth, or a musty smell — signs of persistent moisture and decay.
- Check for borer exit holes — small round holes in the timber surface, often with fine powdery frass nearby.
- Look at the pile top where it meets the bearer. This joint is often the first place moisture collects and rot begins.
- Check whether piles are leaning, cracked, or have separated from the bearers above.
- Look for standing water or very damp soil under the house — chronic moisture accelerates decay.
Outside the House
- Walk around the perimeter and look for visible piles that are leaning or have sunk.
- Check that subfloor ventilation (air bricks or vents) is unblocked — poor airflow is a major cause of subfloor moisture problems.
What the Condition Ratings Mean
A useful way to think about pile condition:
| Condition | What You Might See | Likely Action |
|---|---|---|
| Good | Hard timber, no rot, no borer | Monitor annually |
| Fair | Minor surface checking, slight softness at base | Professional assessment soon |
| Poor | Significant rot, active borer, leaning | Professional assessment urgently |
| Failed | Pile has collapsed or separated from bearer | Stop use of area; call a professional immediately |
Limitations of a DIY Check
Your eyes and a screwdriver will only get you so far. A professional building inspector has access to moisture meters, probe rods, and structural knowledge to assess how many piles are affected, whether the bearers and joists are also compromised, and what the ground conditions are like. They can also identify issues that aren't visible from a crawl-space, such as piles that have rotted internally while still looking sound on the outside.
BRANZ (the Building Research Association of New Zealand) provides technical guidance on subfloor construction and moisture management that underpins best-practice inspection — see BRANZ for research and guidance documents.
Building Consent and Restricted Work
Replacing piles is structural work under the NZ Building Code and will generally require a building consent from your local council. Some limited like-for-like pile replacement may fall under Schedule 1 exemptions, but this varies — always confirm with your council before starting any work. You can find guidance on consents and exemptions at MBIE Building Performance.
The physical replacement work must be carried out by (or supervised by) a Licensed Building Practitioner (LBP) in the relevant licence class. Check that anyone you hire holds a current licence at Licensed Building Practitioners.
When to Call a Professional
Call a qualified building inspector or LBP promptly if you find:
- Any soft or rotten timber when you probe with a screwdriver
- Active borer infestation across multiple piles
- Noticeable floor slope of more than a few millimetres over a metre
- Piles that are leaning, cracked, or have separated from bearers
- A failed or collapsed pile — treat this as urgent
Even if your check comes back looking okay, it's worth having a professional inspection every 5–10 years, or before buying or selling a property. A qualified building inspector will provide a written report you can rely on. You can find experienced local building inspectors and LBPs on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
BCITO Qualified
