Roger Sutton - Patience urged in orange zone | Canterbury Opinion | Local Voices from Canterbury, New Zealand

Canterbury's residential rebuild has been boosted by two vital decisions - further orange-to-green rezoning and new residential foundation design categories for repairing or rebuilding homes in the green zone in Canterbury.  

The Government's announcements last Friday saw 6430 orange-zone properties rezoned to green. Homeowners in these areas can now work with EQC to repair their land, if required, and with their insurer or EQC to repair and/or rebuild houses.  

There are still 1666 residential properties that remain orange and as I have said before in this column, there are many technical reasons for such rezoning delays. In summary, while I want urgency, it's even more crucial to have accuracy. Frustrating as it is for those still orange, we are continuing to investigate and evaluate options and I ask them to hang on for a while longer. We hope to be able to rezone all orange zone areas by Christmas.  

Understandably, we have had many questions since Friday from those wanting to know why new categories for foundation design were necessary and asking how they are personally affected.   The most important thing to note about the new technical categories is that they only apply to residential properties in the green zone with foundations that are required to be repaired or rebuilt due to earthquake damage or for future major renovations or new builds.  

If the foundations of your home were not damaged by the earthquakes, you will not need or be required to upgrade them.  

The new technical categories for foundation design are designed to reduce the risk of injury to people and damage to homes in any future earthquakes. But the standards will also help to reduce costs and speed up the rebuild.  

Scientific and geotechnical studies are ongoing but we have learnt a huge amount since September 4, 2010. It was found properties in the latest orange zone areas to be rezoned green could be repaired on an individual basis - which is why they have been rezoned green - but many houses would need more robust foundations if they need their foundations repaired or rebuilt.  

Three different "technical categories" set out the foundation design requirements for different parts of greater Christchurch flat areas in the green zone. These standards recognise that different parts of the city will need different foundation designs to mitigate the risk of injury to people and damage to homes in any future earthquakes.

The three technical categories for foundation design are:    

TC1 (grey): Future land damage from liquefaction is unlikely. Standard concrete slabs and timber floors are acceptable for foundation repairs or rebuilds. These requirements were changed earlier this year. Information is on the Department of Building and Housing's website at:   www.dbh.govt.nz/canterbury-earthquake-residential-building   

TC2 (yellow): Minor to moderate land damage from liquefaction is possible in future significant earthquakes. You can use standard timber piled foundations for houses with lightweight cladding and roofing and suspended timber floors or enhanced concrete foundations - ie more robust floor slabs that better tie the structure together as outlined in the website link, above for any foundation repairs or rebuilds.  

TC3 (blue): Moderate to significant land damage from liquefaction is possible in future significant earthquakes. Site-specific geotechnical investigation and specific engineering foundation design is required where foundation repairs or rebuilds are needed.  

For properties not in these categories, normal consenting procedures will apply. Homeowners can find out what category their property is in by visiting the CERA land information website www.landcheck.org.nz.  

Most properties recently-rezoned to green will be in technical category 3 (TC3) and some may need deep foundation piles, but remember whatever category you are in, if your house was undamaged by the earthquakes you will not need or be required to upgrade your foundations. Property owners in TC3 who need to rebuild or carry out repairs  are advised to talk first to your insurer.