It is a good idea for the owners of leaky homes to arrange for a condition and remediation report before repair work begins. The report should discuss remediation options.
These reports should be prepared by a qualified NZIBS Building Surveyor or other specialist consultant who has had specific weathertightness training and has the necessary equipment. Reports prepared by a builder or designer may not be as comprehensive or as reliable as one from a specialist.
Because most building condition and remediation reports are prepared before any cladding is removed, they cannot always accurately identify the full extent of the damage (particularly to untreated framing) that will be discovered once work starts. The designer may need to call on the skills of the recognised specialist for advice on how to deal with any additional problems that are found as building repair progresses.
Where a NZIBS Building Surveyor’s report has been prepared for the property, it should be comprehensive, but there is always the risk that something is overlooked. The remediation designer needs to be satisfied that any report provides sufficient information to base a design on.
Designers should discuss any condition and remediation report with the author if possible and obtain further advice if the report does not provide the required information.
What should be in the report
The MBIE publication Weathertightness: Guide to the diagnosis of leaky buildings provides useful information on what a building condition and remediation report should contain. It should:
- identify weather conditions in the period before the investigation was carried out (a period of drier than normal weather before an inspection may skew some of the moisture content readings)
- identify the wind zone, exposure, climate and other relevant environmental factors
- identify the weathertightness risk of the building design and all of the risk features present
- identify the structural system – timber framing, steel framing, precast concrete or concrete masonry
- assess the likely level of framing timber treatment (this is difficult to do and can only be confirmed once the framing is exposed, because treatment of the timber used will depend on location, framing element and supplier)
- identify the causes and locations of water entry (designers should check that this is consistent with what was observed during the site visit)
- be based on sufficient invasive and destructive analysis of problem areas and testing of timber samples
- assess the extent of damage and provide an estimate of the cost of repairs
- identify ‘active’ and ‘inactive’ defects – both types of defects are important when considering repair priorities
- assess the failure as widespread or localised
- assess the durability of the existing building
- have no omissions that need to be investigated further or recommend where further investigations are required if this is the case
- recommend an appropriate remediation strategy for the building.
A report should also:
- identify critical dates – When did construction commence? What was the completion date? When was the building occupied? When was a Code compliance certificate issued? Was it built over winter when conditions are likely to be wetter?
- particularly where a legal claim exists, reference:
- copies of producer statements and product warranties
- certifier, council and later BCA records of inspections – inspection notes will also track the actual construction process and help identify when stages of the work were completed
- BCA notices to rectify or notices to fix
- trade and technical literature current at the time the building was built
- communication records, if they can be obtained, such as the designer’s and builder’s site notes, diaries or records
- address trade and building practice current when the building was built (trade practices and Building Code requirements have changed significantly over the past decade)
- identify other issues with the building, such as any bathroom leaks (a bathroom leak on an external wall is likely to be repaired as part of the weathertightness remediation)
- identify changes made to construction methods or materials used during the building process.
The designer may also need to:
- consider the time period that has elapsed since the report was issued – in some cases, this may mean the damage has got worse
- identify any work carried out on the property as a permanent or temporary repair and the impact this may have had on the extent of the deterioration, noting that not all repairs may have been successful.
While reports may appear comprehensive:
- they may not have identified all faults
- they may not be sufficiently detailed to base a remediation design on.
Some owners wishing to evaluate and/or repair the building may approach a designer directly. In these cases, as noted above, BRANZ recommends that the designer have the owner commission a report by a remediation specialist experienced in this type of work. It is unlikely that many designers will have the experience and equipment that a recognised specialist has. It is also beneficial to consult designers who are familiar with the process and types of standard solutions.
Updated: 10 January 2022