Monolithic cladding — think solid-plastered systems, fibre cement, or EIFS (Exterior Insulation and Finish Systems) — can last decades when properly maintained, but it can also hide serious moisture problems. The key question is whether your cladding is structurally sound underneath and just needs a fresh coat, or whether water has already done enough damage to warrant a full replacement. Here's how to work through that decision.
What Is Monolithic Cladding?
Monolithic cladding refers to exterior wall systems that appear as one continuous surface, with no visible gaps or joints. Common types in New Zealand include:
- Solid plaster over a substrate (brick, block, or timber framing)
- Fibre cement sheet systems (such as those made by James Hardie)
- EIFS (polystyrene-backed render systems, sometimes called "leaky home" cladding)
- Texture-coated fibre cement or hardboard
Many homes built between the late 1980s and early 2000s used monolithic cladding systems that, combined with poor detailing and untreated timber framing, led to widespread moisture ingress — the so-called "leaky building" crisis. This history means any assessment needs to be taken seriously.
Signs That Recoating May Be Sufficient
If the cladding substrate is still sound, a professional recoat can restore weatherproofing and appearance. Look for these positive indicators:
- Surface crazing or hairline cracks that don't penetrate deeply into the render
- Fading, chalking, or peeling topcoat with no signs of moisture beneath
- Minor surface mould that cleans off without staining the substrate
- Solid, firm feel when you tap the surface (a hollow sound can indicate delamination)
- No visible rust staining from corroding fixings or reinforcing mesh
- Intact sealants around windows, doors, and penetrations, or sealants that simply need renewal
If the cladding passes a careful visual and tap test, a qualified renderer can assess whether preparation, crack filling, and a quality exterior coating system will do the job.
Warning Signs That Point Toward Full Replacement
Some signs suggest the damage goes deeper than the surface. These should prompt a thorough professional investigation:
- Bulging, blistering, or delaminating render — the coating has separated from the substrate
- Large structural cracks (wider than about 2–3 mm, or cracks that follow a pattern suggesting movement)
- Soft or spongy areas when pressed, indicating wet or rotted substrate
- Persistent interior damp patches, mould on internal walls, or musty smells
- Rust streaks running down the wall from fixings or mesh
- Visible rot or staining at the base of the wall, around windows, or at junctions
- A home built in the 1990s or early 2000s with monolithic cladding and no cavity — this is a high-risk combination worth investigating thoroughly
BRANZ has published extensive research on monolithic cladding failure modes and is a reliable technical reference for understanding what can go wrong.
The Importance of a Moisture Investigation
Visual checks alone are not enough for monolithic cladding. A moisture investigation using a calibrated moisture meter — and ideally an invasive inspection (opening up small sections of the wall) — is the only reliable way to know what's happening behind the surface.
MBIE Building Performance provides guidance on weathertightness assessments and the formal Weathertight Homes Resolution Service (WHRS) process for homes that may qualify. If you suspect significant damage, a Licensed Building Practitioner (LBP) or a weathertightness assessor should carry out a formal report before any remediation work begins. You can find LBPs through Licensed Building Practitioners.
Do You Need a Building Consent?
This depends on the scope of work:
| Work Type | Consent Likely Required? |
|---|---|
| Recoating / repainting only | No (Schedule 1 exempt) |
| Crack repair and recoat | Generally no |
| Partial cladding replacement (like-for-like) | Possibly — check with your council |
| Full recladding with a new system | Yes, almost certainly |
| Adding a drained cavity to existing cladding | Yes |
Always confirm with your local council before starting work. What qualifies as a Schedule 1 exemption can vary, and getting it wrong can cause problems when you sell. See MBIE Building Performance for general guidance on consents.
Choosing the Right Coating System
If recoating is the right call, product selection matters. The coating must be breathable (vapour permeable) to allow any residual moisture to escape, while remaining weatherproof. Leading NZ paint brands offer suitable exterior systems — Resene, Dulux, and Wattyl all have textured and smooth exterior coatings designed for render and fibre cement substrates. Your renderer will advise on the right system for your specific cladding type.
Proper surface preparation — cleaning, treating mould, filling cracks with a flexible filler, and priming — is just as important as the topcoat itself.
When to Call a Professional
Always engage a qualified renderer or weathertightness assessor if:
- You find any of the warning signs listed above
- Your home was built between approximately 1988 and 2004 with monolithic cladding
- You're unsure about the cladding type or its history
- You're planning to sell and want certainty about the cladding's condition
- Any recladding or structural repair work is needed
A skilled renderer can tell the difference between a cosmetic issue and a structural one — and attempting a recoat over a failing substrate will only delay (and worsen) the problem. You can find qualified local renderers and building tradespeople on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
