Initial Seismic Assessments (ISAs)

CCC LIM Advisory Note

Beginning in November 2024, I began to receive enquiries from clients buying and selling their residential units in Christchurch when they noticed that Christchurch City Council (CCC) had begun adding an advisory note to their LIMs (Land Information Memorandums)..

The text of the advisory note is as below:

"This is a general advisory note that is applied to properties where the buildings are within the scope of what could be earthquake prone building (in this case a building that comprises of 2 or more storeys and contains 3 or more household units), and their construction predates the Canterbury earthquakes of 2010 and 2011, and Council has no record of an engineering assessment.

Please note, Council has no records for this property of specific concerns about structural damage to this building, in addition Council has not made a request for an engineering assessment under section 133AH, Building Act 2004".

How I Can Help

I am currently working with building owners who would like the LIM note removed prior to sale, and am also acting on behalf of buyers who may want confidence that they will be able to remove the LIM note after purchase. CCC have removed the note from the LIMs following submission of my ISA (initial seismic assessment) for the property along with a memorandum setting out how I've carried out the assessment and what the findings and recommendations are.

I would typically do one report for the whole building, but there can be complications if the units are connected in unusual ways or for example one unit depends entirely on their neighbouring unit for its strength. On some projects the unit owners have decided between themselves to go ahead with the report and share costs.

To carry out the ISA I require the council’s property files and a site visit. Any additional information such as EQC reports and records of previous strengthening and repair work can be helpful too. The reporting is based on as assessment of the original design and known modifications over the years.

Fees depend on complexity and the size of the building so please give us a call to discuss.

Council Requirements

The Council's threshold to remove the note from the LIM is 34%NBS (New Building Standard). This is quite achievable for most residential buildings if they are only two storey, rectanguler in plan, and have walls in both directions. Unusual floor layouts and suspended concrete floors with badly considered connection detailing are the most common issues identified. If there is a problem identified in an ISA, I would recommend further investigation and targeted calculations which may include a DSA (detailed seismic assessment).

New Building Standard - NBS

In New Zealand, %NBS stands for "Percentage of New Building Standard". It is a measure used to assess the seismic performance of a building compared to the requirements for a new building under the current building code.

A new building designed today to meet all current seismic standards is considered 100% NBS.
An existing building is assessed to determine how its ability to withstand earthquakes compares to a new building. For example:
- If a building is rated 67% NBS, it is considered to perform 67% as well as a new building under the same conditions.
- A building with less than 34% NBS is considered earthquake-prone, meaning it has a higher risk of significant damage or collapse during an earthquake.

In summary, the %NBS tells us how a building stacks up against the modern safety standards. You can learn more about this on the MBIE website linked here Managing earthquake-prone buildings | Building Performance