Territorial authorities must consider all the building characteristics required by regulation before granting an exemption. This includes the likely consequences of building failure for life safety and damage to other property, and current and expected use. Priority buildings are unlikely to be granted an exemption.
Territorial authorities apply judgement based on available evidence
Territorial authorities must grant an exemption if satisfied that an earthquake-prone building or part has all the characteristics set out in the regulation; ie it:
- has limited current use, and
- has limited expected use, and
- is expected to cause limited harm, and
- is expected to cause limited damage, and
- would not affect any strategic transport routes (this is only relevant in high and medium seismic areas), and
- is unlikely to be required in an emergency.
Some of these characteristics are straightforward, such as whether the building is likely to be needed in an emergency. Other characteristics involve more judgement, such as whether the building is likely to continue to be used by a low number of people.
Scenarios: Exemptions from carrying out seismic work provides examples of how this judgement might be applied.
Priority buildings are unlikely to be granted an exemption
Priority buildings are unlikely to have the characteristics necessary for an exemption, as the consequences of a priority building’s failure will be high.
Priority buildings are buildings in high or medium seismic risk areas that are considered to pose a higher risk to life safety than other earthquake-prone buildings, or are buildings critical to recovery in an emergency.
- Hospitals, education buildings, and priority buildings on busy thoroughfares are unlikely to have low enough numbers of people inside or in close proximity to justify an exemption.
- Buildings on strategic transport routes (routes likely to be needed in an emergency that the territorial authority has identified for the purpose of considering priority buildings) are also unlikely to qualify for an exemption, as the consequence of impeding these routes would be high.
Priority buildings has further information.
Territorial authorities must consider current and expected use
The territorial authority must consider the building’s characteristics at the time of the application and also in the foreseeable future. For example, if a building is unoccupied when the owner applies for an exemption because a tenancy has just ended, the territorial authority should consider whether this status is likely to continue. If the building is not near any other property (excluding land), the territorial authority should check there are no current plans for anything to be built on a neighbouring property.
Consequences for life safety must be limited
The ‘intensity of occupation and passage’ of an earthquake-prone building must be reasonably low before a territorial authority can grant an exemption. In deciding this the territorial authority will need to consider:
- how many people are likely to be in or near the building
- how often this is likely to occur, and
- for how long.
These factors taken together paint a picture of the overall building use. The regulations allow different combinations of these factors so territorial authorities can consider the particular circumstances of an earthquake-prone building or part.
While these factors may vary, buildings granted an exemption will have similar (low) levels of associated risk overall. The graph below shows how the life-safety risk can change given different combinations of these factors.
For example: A particular building does not have any regular visitors but is used for a church service by a large group once or twice a year. Another building is empty except for a short weekly visit by a maintenance person. Both buildings could have a similar occupancy overall (based on the number of people multiplied by how often they visit and the total time spent) and therefore a similar life-safety risk, all other things being equal.
Life-safety consequences based on likely/anticipated building use
Click the graph to enlarge.
The regulations define two levels for intensity of occupation and passage: nil to low, and low to moderate. This differentiation is intended to help territorial authorities consider the life-safety consequences if the building were to collapse.
If the building has nil to low intensity of occupancy and passage, the life-safety consequences of the building’s failure are automatically considered to be low. No further evidence is required.
If the building has low to moderate intensity of occupancy and passage, the territorial authority will need more information to assess the life-safety consequences of its failure.
The applicant must provide evidence to show that because of the way the building is expected to collapse no more than a low number of people inside or nearby are likely to be harmed. It is expected that an engineering assessment will be used to support this consideration. Where an assessment is not available, a territorial authority may not be satisfied that the building has the necessary characteristics.
Understanding ‘nil to low’ and ‘low to moderate’ intensity has further information.
Consequences for other property must also be low
The territorial authority must also consider the amount of damage the collapse of the earthquake-prone building/part would be likely to cause to other property. It cannot grant an exemption unless there is likely to be minor or no damage as a result.
The territorial authority should start by considering the area surrounding the building. If there is no neighbouring property (excluding land) and there is not likely to be any in the foreseeable future, this characteristic is satisfied.
If there is other property nearby, the territorial authority should consider how the building is expected to collapse in an earthquake (as detailed in an engineering assessment) and the likely consequences of this. Where an assessment is not available, a territorial authority may not be satisfied that the building has the necessary characteristics.