The Building Act has rules around whether or not building or renovation work should get a building consent when the house is in an area subject to natural hazards.
Under Section 71 of the Building Act, building consent authorities must refuse to grant a building consent for building work (including alterations that require consent) if:
- the land is subject or is likely to be subject to 1 or more natural hazards (erosion, falling debris, subsidence, inundation [flooding] or slippage); or
- building work is likely to accelerate, worsen, or result in a natural hazard on that land or any other property.
BCAs can, however, issue consent if they are satisfied that there is adequate provision:
- to protect the land, building work, or other property from the natural hazard or hazards; or
- to restore any damage to that land or other property as a result of the building work.
BCAs must issue a consent for building or renovations on land subject to natural hazards if they consider that the work will not worsen the hazard and they believe it is reasonable to grant a waiver or modification of the Building Code for the natural hazard concerned (Section 72).
If consent is given for building work on land subject to natural hazard, a note will be added to the certificate of title that a building consent was granted under Section 72, identifying the natural hazard concerned.
Where a land title has this note on it, the Earthquake Commission can legally decline to provide cover, depending on the nature of the hazard. Insurance companies may decline to offer cover, or may exclude cover for the relevant hazard.
On some sites there may be hazardous microclimates that may lead to problems such as rapid corrosion of metal fasteners and fixings. As an example, the scope of NZS 3604 Timber-framed buildings specifically excludes:
- Industrial contamination and corrosive atmospheres
- Contamination from agricultural chemicals or fertilisers
- Geothermal hot spots – areas within 50 m of a bore, mud pool, steam vent, or other source.
In these circumstances, building and renovation work requires specific engineering design.