Uncovering unexpected structural problems during demolition is a reality many NZ homeowners face — especially in older homes built before modern building codes. Whether it's rotted framing, earthquake damage, substandard foundations, or illegal alterations, knowing what to do next can save you time, money, and stress.
Why Unexpected Problems Are So Common in NZ
New Zealand's housing stock includes a large number of homes built in the early-to-mid 20th century, many of which predate NZS 3604 (the standard for timber-framed buildings) and modern requirements under the NZ Building Code. Decades of weather exposure, deferred maintenance, and DIY modifications mean that walls, floors, and roofs can hide serious issues that only become visible once demolition begins.
Common surprises include:
- Rotted or termite-damaged framing hidden behind cladding or linings
- Substandard or missing bracing that doesn't meet current earthquake standards
- Unlconsented alterations — walls removed or added without a building consent
- Asbestos-containing materials (ACMs) in pre-1990 homes
- Foundation problems such as cracked concrete pads, inadequate piles, or subsidence
- Water damage and mould concealed behind linings
Stop Work and Assess the Situation
If your demolition contractor uncovers something that looks structurally significant, the first step is to stop work in the affected area. Continuing to demolish around a compromised structure can be dangerous and may make the problem worse.
A reputable demolition contractor will flag the issue immediately and document it with photos. This is standard professional practice and protects both you and the contractor.
Notify Your Council if Required
Depending on the nature of the discovery, you may need to notify your local council. If the work already has a building consent, any significant change to the scope — such as discovering that additional structural repairs are needed — typically requires an amendment to that consent before work continues.
If the original demolition was being carried out under a Schedule 1 exemption (work that doesn't normally require consent), uncovering structural issues that require repair may push the project into consented territory. Always check with your local council before proceeding — rules can vary between territorial authorities.
For guidance on what requires consent, MBIE Building Performance is the authoritative source.
Get a Structural Engineer Involved
Once unexpected structural problems are found, you'll almost certainly need a Licensed Building Practitioner (LBP) or a structural engineer to assess the situation. An engineer can:
- Determine whether the structure is safe to continue working around
- Specify what remedial work is needed
- Provide documentation required by your council
You can check that any LBP you engage is properly licensed at Licensed Building Practitioners.
Asbestos: A Special Concern
Pre-1990 NZ homes frequently contain asbestos-containing materials in areas like wall linings, floor tiles, roofing, and insulation. If demolition uncovers suspected ACMs, work must stop immediately in that area.
Under WorkSafe NZ regulations, the removal of more than a small amount of asbestos (Class B or Class A work) must be carried out by a licensed asbestos removalist. This is not DIY territory — asbestos fibres are a serious health hazard. Your demolition contractor should be across these requirements, but it's worth confirming before work starts.
Restricted Work: What Only Licensed Tradespeople Can Do
Once structural problems are identified and remediation begins, you may need several licensed trades involved:
| Trade | Restricted Work | Licensing Body |
|---|---|---|
| Electrician | Any electrical wiring or connections | EWRB |
| Plumber/Drainlayer | Sanitary plumbing, drains | PGDB |
| LBP | Structural, weathertight, and other restricted building work | LBP |
Never attempt restricted work yourself — it's illegal, can void your insurance, and creates serious safety risks.
How This Affects Your Budget and Timeline
Unexpected structural finds almost always mean additional cost and time. As a rough guide, remediation of hidden structural issues can add anywhere from a few thousand dollars for minor framing repairs to significantly more for foundation work or widespread rot — but costs vary enormously depending on the extent of damage and your location.
It's wise to build a contingency of 10–20% into any demolition or renovation budget for exactly this reason. Talk to your contractor upfront about how unexpected discoveries will be handled contractually.
BRANZ publishes useful research on NZ building performance and common defects that can help you understand what issues are typical for your home's era.
When to Call a Professional
You should engage a qualified professional immediately if:
- Your demolition contractor flags a structural concern
- You see signs of significant rot, cracking, or movement
- Suspected asbestos is uncovered
- The structure appears unstable or unsafe
- You're unsure whether the work now requires a building consent
A qualified demolition contractor will manage much of this process for you, but it's important to stay informed as the homeowner. You can find experienced, local demolition contractors on tradedirectory.co.nz.
SiteWise
Tōtika Prequalified
ISO 45001
