Building on land subject to natural hazards

If you are unsure whether the land you intend to build on is subject to natural hazards, obtain a Project Information Memorandum. This will tell you if there are any natural hazards that council is aware of.

Natural hazard under Building Act sections 71 to 73 means

  • erosion (including coastal erosion, bank erosion and sheet erosion)
  • falling debris (including soil, rock, snow and ice)
  • subsidence
  • inundation (including flooding, overland flow, storm surge, tidal effects and ponding)
  • slippage.

Your building consent will still be granted if we decide that your proposed work will not accelerate, worsen or result in a natural hazard on yours or other property.

We will let you know if your building consent application is being considered under Section 72 during the processing of your consent. If there is a natural hazard, then

  • the hazard will be registered on your record of title, and
  • there will be a fee for you to pay for notifying this to Land Information New Zealand (LINZ).

You can check Selwyn's flooding and coastal hazard details on Canterbury Maps.

As part of the building consent process you may need to apply for a waiver or modification in connection to the natural hazard. You’ll need to confirm that you understand the potential effects the identified hazard may have on your insurance and any future sales.

You have the opportunity to withdraw your building consent application at this point. There will however still be costs to pay for time already spent processing your application to this stage.

Geotechnical reports

You will need to provide a geotechnical report

  • if your land is identified as being in an area that is susceptible to liquefaction, or
  • for areas where other natural hazards such as loess or faultlines are present.

A map of liquefaction zones is available on page 17 of the 2012 Environment Canterbury (ECan) report reviewing liquefaction hazard information [PDF, 4856 KB].

Obtaining a Project Information Memorandum before applying for your building consent will confirm whether you need to supply with your building consent documentation

  • a full geotechnical report, or
  • a shallow soil investigation report.

Site investigations usually involve the drilling of boreholes or digging of test pits, scala penetrometer tests, with samples and testing carried out. These confirm

  • the ground conditions beneath the site, and
  • will identify any problems that may exist with the stability of the site or the subsoils.

The geotechnical report or shallow soil investigation report present the findings of the site investigation and recommend the appropriate foundations and stabilising measures, retaining walls etc for specific projects. These are therefore an important part of the design process.