The Council sets minimum floor levels to protect buildings throughout the city from the risk of flooding. If you are building, rebuilding or extending, your building may need to be built to the new floor level requirement.
The floor levels have been assessed based on the best available flood model information with the addition of a margin known as freeboard.
Freeboard is the term given for an allowance in floor levels above the modelled flood level, which allows for modelling inaccuracies, construction tolerances, network failures and natural environmental factors such as wave and wind effects.
All local authorities have a freeboard level. This tends to vary from 300 millimetres to 500 millimetres. Freeboard in Christchurch has been 400 millimetres above the flood level for many years. If you wish to propose a different freeboard for your building this will require a technical justification to be processed.
It is important to remember Christchurch is a generally flat, low-lying city and there have always been areas prone to flooding. The Council has always set minimum floor levels in these areas and updates these as new information becomes available.
The Council is also working to mitigate the risk of flooding, having already raised stop banks in the worst affected areas close to the rivers, and has a land drainage recovery programme in place.
The Council continues to model the effects of surface water and at times this will lead to changes to the required minimum floor levels for a site. If you are designing works that require consent then we recommend that you regularly check the website and consider contacting our floor level advice team (firstname.lastname@example.org) for any information on upcoming modelling.
If your property is in the Flood Management Area (as defined in the District Plan) and you are planning to build or add to your existing building, you may be required to meet a minimum floor level to provide protection from a one-in-200-year flood event.
Existing use rights may allow a property owner to rebuild their home within 12 months without the need to comply with the updated floor level requirements, if they rebuild on the same footprint and the new building is of the same or similar scale, intensity and character. Even if you have existing use rights, you will be strongly encouraged to consider rebuilding at the updated floor levels for new development in Flood Management Areas, both for your safety and the safety of future occupants of the property.
It is also important to note that even if you have existing use rights to rebuild at lower floor levels, you will still need a building consent for most works. This will include complying with the Building Code minimum floor level requirements, providing protection from a one-in-50-year flood event. The minimum floor level requirements do not apply if you are repairing your home, unless the repair work requires a resource and/or building consent and triggers reassessment of floor level compliance as part of the consent process.
Final minimum floor level requirements for each property will be set as part of the consent process but property owners can expect these to be the same or similar to those indicated in this floor level map.
The extent of the Flood Management Area and minimum floor level requirements have been updated via the District Plan review to protect homes and businesses from the risk of future flooding. Section 5.4 of the Christchurch District Plan sets out rules for activities and earthworks in the Flood Management Area, including the minimum floor level requirements.
In some areas the required minimum floor levels have been established by the Council and are specified in the District Plan. This area is referred to as the Fixed Minimum Floor Level Overlay area.
In other areas, the floor levels may require further assessment and a Minimum Floor Level Certificate must be obtained from the Council for all new buildings, and additions to existing buildings that increase the ground floor area of the building. The certificate will set the minimum floor level for the building and is valid for two years. You can request a certificate using the P-022 Request for District Plan Certificate: Minimum Floor Level application form, which is available on the forms and checksheets webpage.
Please note that recession planes are measured from the minimum floor level (or natural ground level if this is higher) for residential properties within the Flood Management Area for activities permitted under Rule 184.108.40.206 P1-P4 (new buildings and additions that meet the required minimum floor levels).
Further information is available by contacting us to talk to the Duty Planner.
If the District Plan requirements do not apply to your project and you would like to discuss the Building Code floor level requirements, please contact us and ask to talk to the Duty Building Consent Officer.