There is toxic mould and decaying timber frames in the walls of Tauranga's courthouse, according to a previously-withheld report which found it did not comply with the building code.

A raft of issues with the 53-year-old courthouse – including toxigenic mould Stachybotrys, the spores of which are a risk to human health – were discovered during a Ministry of Justice-commissioned investigation in 2016, which the Bay of Plenty Times Weekend can make public today for the first time.

The ministry refused to release the 2016 weathertightness report to the Bay of Plenty Times in an Official Information Act response earlier this year, but after a complaint to the Ombudsman, changed its decision.

The wall-cladding weathertightness assessment – prepared less than a year after the ministry spent almost $1 million on roof repairs at the courthouse – found a full reclad was needed to properly fix the building.

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"This is the only way to provide any degree of certainty in achieving a dry environment for the structure and ensure the future durability of the building," the report recommended.

The report, by Prendos New Zealand Ltd, said the remedial work would need full design documentation and a building consent application.

But no such building consent application has been filed with Tauranga City Council, according to a council spokeswoman.

The Bay of Plenty Times Weekend asked the ministry if a full reclad of the courthouse had occurred since 2016 and if the building had been brought up to a code-compliant standard.

In response, Fraser Gibbs, the ministry's general manager of commercial and property, said: "The roof work that the ministry has carried out has stopped many of the issues worsening and the building has a current building warrant of fitness.

"The issues highlighted in the reports you received will be addressed as part of a proposed redevelopment of the building. The building received a code of compliance when built and any future works will be required to meet current code of compliance requirements."

Air quality tests at the courthouse are being conducted monthly to ensure there is no risk to occupants' health. A test in May this year found all rooms and areas were safe to be used and there no was immediate health risk.

A maintenance plan is in place and monitoring of water-damaged wall and ceiling linings continues.

The weathertightness report identifies the presence of Stachybotrys.

"This is currently contained within the construction of the walls and should therefore pose a low risk to the health of building users and occupants unless it is disturbed. However, precautions will need to be undertaken when remediating the building," the report said.

An invasive investigation of the wall cladding and associated elements in July 2016 confirmed water was accessing the wall framing timber, causing timber decay and mould growth.

In the report, the issues were summarised as follows:

• Water is penetrating the directly fixed cladding at unsealed cladding joinery junctions, canopy roof/wall junctions, parapet/wall junctions and at the base of the cladding where ground clearances have been compromised.

• The direct fixed cladding installation does not allow for moisture that penetrates behind the cladding to dry out quickly, nor drain to the exterior.

• The consequences of this entrapped moisture is timber frame decay, mould growth and associated damage to the building fabric.

The report said given the issues identified, the Tauranga courthouse building did not comply with the New Zealand Building Code in terms of clause B2 – Durability and clause E2 – External Moisture.

"In order to bring the building up to a code complaint standard, the existing direct fixed cladding should be removed, damaged structure and fabric replaced followed by a new cladding installed over a drained and vented cavity system. These works should be programmed as soon as possible."

The report said an initial seismic assessment was also recommended as part of the remedial design "so as to highlight potential structural deficiencies".

"We noted some potential structural deficiencies and these deficiencies should be addressed as part of remediation design."

Gibbs said a number of issues with the Tauranga courthouse had been identified and the ministry was looking at a proposed redevelopment of the building.

"In the meantime, the ministry has fixed the leaks into the courthouse by replacing the roof with a new membrane system which can be altered with ease to assist with weathertightness facade repairs in the future.

"Until the redevelopment plan and the various options involved have been finalised, we are unable to comment on any other work or actions we are considering."

Timeline

1965: The original Tauranga courthouse is built.
1981: Additional floor area takes the total size of the building to 1441sq m.
1983: Two courtrooms are added, along with holding cells, a judge's room and bailiff facilities.
1996: A further 845sq m added.
1998: An extensive upgrade is completed.
2015: Ministry of Justice spends $998,000 (excluding GST) replacing the roof, completed in November, after numerous roof leaks over several years.
2016: A wall cladding weathertightness assessment, produced in July, finds toxic mould and decaying timber frames in the walls of the courthouse. Report says a full reclad is required to properly remediate the building, which is found to not comply with the building code.
2017: Ministry responds to seven leaks at the courthouse in the space of a year – six attributed to faulty air conditioning and one to a buildup of debris in a gutter.
2018: During a visit to Tauranga, Justice Minister Andrew Little is told by court officials and concerned local lawyers about ongoing leaking and weathertightness issues at the courthouse.
2018 (April): Minister Little tells the Bay of Plenty Times there are plans to completely redevelop the site and says, as he understands it, the existing courthouse needs to come down and a new building be put in its place.
2018 (August): Asked if a full reclad of the courthouse has occurred and if the building has been brought up to a code-compliant standard, the ministry says the courthouse has a current building warrant of fitness and received a code of compliance when built. It says it is looking at a proposed redevelopment, has fixed leaks into the building, and a continuing maintenance plan is in place, including monthly air quality tests.