Checking whether your home has a cavity cladding system is an important step in understanding its weathertightness and long-term durability. Homes built or reclad after around 2005 are far more likely to have a cavity, but many older homes — particularly those built during the 1990s and early 2000s — were constructed with direct-fixed cladding, which has been linked to widespread leaky building issues across New Zealand. Here's how to check what your home has, and what to do if you're unsure.
What Is a Cavity System and Why Does It Matter?
A cavity cladding system (also called a drained and ventilated cavity) places a small gap — typically 20 mm — between the exterior cladding and the building wrap or substrate beneath. This gap allows any moisture that penetrates the cladding to drain away and the cavity to dry out, dramatically reducing the risk of water damage and rot.
Direct-fixed cladding, by contrast, is fixed flush against the wall framing with no gap. If moisture gets in, it has nowhere to go, which can lead to serious structural damage over time. The BRANZ has extensively documented the performance difference between these two systems.
Under the current NZ Building Code, Clause E2 (External Moisture) requires new cladding systems to manage moisture effectively. Since around 2005, most compliant cladding installations have required a drained cavity, though the exact requirements depend on the cladding type, wall exposure zone, and design details.
Step 1: Check the Age and Consent History of Your Home
Start with your building consent records. Contact your local council or check your LIM (Land Information Memorandum) report to find out when the home was built or last reclad, and what cladding system was consented. Homes built before 1995 or after 2005 are at opposite ends of the risk spectrum — pre-1995 homes often predate the problematic era, while post-2005 homes are more likely to have a cavity.
Homes built roughly 1995–2004 are the highest-risk group for direct-fixed, monolithic-style cladding without a cavity.
Step 2: Look at the Cladding Type
The type of cladding on your home gives strong clues:
- Fibre cement (e.g. James Hardie products) — could be either direct-fixed or cavity-fixed depending on the era and installation method. Check the James Hardie installation guides for your product.
- Stucco or monolithic plaster — commonly direct-fixed in the leaky building era; may or may not have a cavity depending on when it was installed.
- Weatherboard (timber or fibre cement) — more likely to have some drainage capacity, but not always a full 20 mm cavity.
- Brick veneer — typically has a built-in cavity by design.
- Vertical or horizontal profiled metal cladding — usually has a cavity, but confirm with documentation.
Step 3: Inspect Around Openings and Penetrations
One of the easiest ways to check for a cavity is to look closely at window and door reveals, meter box openings, or external tap penetrations. If there is a cavity, you may be able to see a gap between the cladding and the wall framing at these edges. A gap of around 20 mm is a good sign a cavity exists.
You can also check at the base of the wall — cavity systems typically have a cavity closer or vented base strip at the bottom of the cladding to allow drainage and ventilation while keeping out insects. If you can see a perforated or slotted strip running along the bottom of the cladding, this strongly suggests a cavity system is present.
Step 4: Check Existing Documentation
Look for:
- Original building consent drawings — these should show wall section details including any cavity.
- Producer statements or CodeMark certificates — these may have been supplied by the cladding manufacturer at the time of construction.
- As-built documentation — sometimes held by the original builder or architect.
If you purchased the home recently, your solicitor or the vendor may have supplied some of this documentation during the sale process.
Step 5: Use a Moisture Meter or Probe Test
If you suspect your cladding may be direct-fixed and you're concerned about moisture, a moisture meter can give a preliminary indication of elevated moisture levels in the wall framing. However, this is not a definitive test for the presence or absence of a cavity — it's a symptom check, not a structural diagnosis.
For a definitive answer, a probe test (a small hole drilled through the cladding to physically inspect the cavity) can be carried out by a qualified building inspector. This is minimally invasive and gives a clear result.
When to Call a Professional
If you cannot confirm from documentation or visual inspection whether your home has a cavity, it's strongly advisable to engage a Licensed Building Practitioner (LBP) or a qualified building inspector. They can carry out a thorough weathertightness assessment, including probe testing and moisture readings, and provide a written report.
This is especially important if you are:
- Buying or selling a home built between 1995 and 2004
- Planning to reclad or renovate
- Noticing signs of moisture damage such as staining, soft wall linings, or musty smells
You can find qualified local building inspectors and LBPs on tradedirectory.co.nz. Always confirm that any inspector holds a current LBP licence at lbp.govt.nz.
Note: Any recladding work that requires a building consent must be carried out or supervised by a licensed building practitioner. Check with your local council before starting any significant cladding work — some work may qualify as exempt under Schedule 1 of the Building Act, but this depends on your specific situation.
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