Invasive Testing

You can download our expert report or read more about this on our website.

Monolithic plaster-clad houses are considered high-risk because many were built with untreated or undertreated timber, with no cavity in the walls, inadequate flashings (if any) and poor construction practices. These meant that houses leaked, often without outward signs, the leaks couldn’t dry out, and the wet timber framing decayed.

The main high-risk period is between around 1992 and 2004. Weatherboard and brick homes can also be affected.

The questions that potential buyers of these houses must ask themselves are:

1. Will I be able to maintain the house at an affordable cost?
2. Will I be able to find a buyer for the house at the price I want, when the time comes to sell?

Buyers should conduct an appropriate level of inspection to give them reasonable assurance as to the house’s condition.

In many cases, leaks are concealed within the walls with little to no visual evidence and are often not detectable with hand-held scanning moisture meters.  Walls can dry out in the summer.  Invasive testing is imperative as these concealed or historical defects can be very expensive to repair and may even lead to re-cladding or rebuilding.

Monolithic plaster-clad houses are attractive because they can be bought at a substantial discount to surrounding brick or weatherboard-clad houses.  Invasive testing can show whether it’s a lemon that will break your heart or a gem that stays safe and dry.

Our BNet website provides more information on potential defects and how these can be diagnosed and remediated.

Visual Inspections

These are normally conducted according to NZ Standard 4306:2005, the standard for residential building inspections, and include reporting on many aspects of the building. They are an important part of a buyer’s due diligence, however, there are limitations to the weathertightness component.

• The tools (scanners and thermal image cameras) used are not technically capable of measuring actual moisture levels or identifying decayed framing timber or timber treatment levels,
• They don’t allow inspectors to move any personal possessions which might be hiding issues,
• They don’t require inspectors to have any expertise in understanding or diagnostics of leaky buildings,
• They leave unanswered questions and often red flags regarding weathertightness,
• They leave buyers of monolithic plaster-clad houses at serious risk of buying a defective house,
• Should recommend invasive testing because visual inspections can miss these serious issues inside the wall.

If you need a standard pre-purchase inspection report, please contact us as we can recommend reputable inspectors with a high level of weathertightness expertise.

Invasive Testing – Moisture Detection Company Process

These are classed as special purpose inspections under NZ Standard 4306:2005 and specifically investigate areas which are considered to be weathertightness risks, or are red flagged in building reports.

• Confirm the results of a standard visual inspection
• Can be carried out together with a weathertightness inspection
• Have minimal impact on the house so are usually acceptable to vendors
• Test for timber condition, moisture percentage and timber treatment
• Are accurate and reliable
• Can leave a permanent moisture probe in place for repeat moisture measurements.

 

Decay Samples from Invasive Testing

• Samples 1,3,4 and 5 are decayed, have no strength and require replacement.
• Sample 2 was found to be untreated timber with no durability against decay.
• Sample 5 was from a location not reported by the Building Inspector.
• Banks would not lend on this property.

No one should ever buy a plaster clad house without knowing how well the timber is treated.  Our Timber Treatment Testing service will tell you.

Timber Treatment Testing is a standard component of our Invasive Testing process.

Having untreated timber is the biggest and potentially the most expensive risk factor when buying a house built between 1992 and 2005 – but most Building Report only mention this  briefly.  Untreated or undertreated timber decays far more rapidly, massively increasing the risk and cost of decay damage, which can even require re-cladding to resolve. The possible cost of repairing this and loss of house value when you sell has to be factored into your buying decision.

We discreetly take timber samples from several locations around the house and test them in our laboratory for the most common treatments used in the timber industry.

You find out whether the timber is treated, the type and amount of treatment used, and what this means for the house and your investment.

Download our information sheet About Timber Treatment Testing

Email us at info@moisturedetection.co.nz or call us on (09) 271 0522.