What Are the Most Common Problems Found in NZ House Inspections?

Getting a pre-purchase building inspection is one of the smartest moves you can make before buying a home in New Zealand. Inspectors assess hundreds of properties every year, and certain problems come up again and again — regardless of whether the house is a 1960s weatherboard or a 2000s brick-and-tile. Knowing what to look out for can save you thousands of dollars and a lot of heartache.

Moisture and Water Ingress

Moisture is by far the most common issue found in NZ building inspections. Our climate — particularly in wetter regions like Auckland, the West Coast, and Wellington — creates ideal conditions for water to find its way in. Inspectors use moisture meters and thermal imaging cameras to detect dampness that isn't visible to the naked eye.

Common moisture problems include:

• Leaking roofs — cracked or missing tiles, failed flashings, and blocked gutters
• Rising damp — moisture wicking up through concrete floors or subfloor areas with poor ventilation
• Leaky building syndrome — a well-documented issue with homes built roughly between 1992 and 2004 that used monolithic cladding systems without adequate weatherproofing details
• Wet subfloors — especially in older homes with limited underfloor ventilation

BRANZ has extensive research on moisture management in NZ homes and is a valuable resource for understanding how buildings should perform.

Roofing Issues

The roof is your home's first line of defence, and it takes a hammering from UV, wind, and rain. Inspectors frequently find:

• Rusted or corroded iron roofing, particularly on homes over 30 years old
• Cracked or slipped concrete and clay tiles
• Failed or poorly installed flashings around chimneys, skylights, and roof penetrations
• Blocked or sagging gutters and downpipes
• Inadequate roof pitch for the cladding type installed

Roofing repairs can range from minor maintenance to full replacement, so understanding the condition of the roof is critical before you sign on the dotted line.

Substandard or Unlicensed Building Work

DIY additions and alterations are extremely common in NZ homes, and not all of them were done to code. Inspectors regularly find decks, sleepouts, garages, and extensions that were built without a building consent — or with one, but not to the standard required by the NZ Building Code.

Key standards like NZS 3604 (timber-framed buildings) set out minimum requirements for structural work. Work done outside these standards can be costly to remediate and may affect your ability to insure or on-sell the property.

Licensed Building Practitioners (LBPs) must carry out or supervise restricted building work. You can verify a tradesperson's licence at LBP.govt.nz.

Electrical Faults

Electrical issues are a serious safety concern and appear regularly in inspection reports. Common findings include:

• Old ceramic fuse boards that haven't been upgraded to modern circuit breakers
• Unprotected wiring in roof spaces or subfloors
• DIY wiring that doesn't meet current standards
• Missing or non-functional safety switches (RCDs)
• Insufficient power points for modern living

What's Restricted Work?

All electrical work in NZ is restricted work and must be carried out by a registered electrician. Homeowners cannot legally do their own electrical wiring. The Electrical Workers Registration Board (EWRB) maintains a register of licensed electricians. If an inspection flags electrical issues, get a registered electrician to assess and quote before proceeding.

Plumbing and Drainage Problems

Plumbing defects are another frequent finding, especially in older homes. Inspectors look for:

• Polybutylene (PB) pipe — a type of plastic pipe used in the 1980s–90s that is known to fail and cause significant water damage
• Leaking or corroded copper pipes
• Poor drainage falls causing slow drains or ponding
• Inadequate hot water cylinder pressure relief or incorrect installation
• Substandard wet area waterproofing that doesn't meet NZ Building Code clause E3

Plumbing and drainlaying are also restricted work in NZ. Any repairs or alterations must be carried out by a licensed plumber or drainlayer registered with the Plumbers, Gasfitters and Drainlayers Board (PGDB).

Structural Concerns

While major structural failures are less common, inspectors do find:

• Subfloor timber decay — piles, bearers, and joists rotting due to moisture or borer damage
• Borer infestation — particularly in older native timber framing
• Cracked or settling foundations, especially in areas with expansive soils or earthquake history
• Inadequate bracing in older homes that predate modern earthquake standards

Insulation and Ventilation Deficiencies

Many NZ homes — particularly pre-2000 builds — have little or no insulation. This is not just a comfort issue; under the Healthy Homes Standards, rental properties must meet minimum insulation and ventilation requirements. Check Tenancy Services for the current requirements.

For owner-occupiers, upgrading insulation is one of the best investments you can make. Energywise has practical guidance on insulation options and potential government support.

Common Problems at a Glance

When to Call a Professional

A building inspection report is a starting point, not a final diagnosis. If your report flags moisture, structural issues, electrical faults, or plumbing concerns, you should engage the relevant licensed professional for a detailed assessment and quote. For complex issues like leaky building remediation or structural repairs, always use an LBP-licensed builder.

You can find qualified local building inspectors, builders, electricians, and plumbers on tradedirectory.co.nz — it's a great way to connect with trusted tradespeople in your area.

Sources & Further Reading

• BRANZ — Building Research
• MBIE Building Performance — NZ Building Code
• Licensed Building Practitioners Register
• Electrical Workers Registration Board
• Plumbers, Gasfitters and Drainlayers Board
• Energywise — Home Insulation