CZIP People living in low-lying areas of Christchurch may need to raise the floor levels of their homes if they are repairing or rebuilding under new city council rules aimed at reducing the risk of flooding.
The council will today release flood-modelling information it has collected since the September 2010 earthquake to enable it to set floor levels for building work across the city.
The information was released to insurers in August but has not been available to property owners until now.
It potentially affects more than 10,000 properties.
Council regulation and democracy services general manager Peter Mitchell said the quakes had caused significant land damage, and ground levels across large areas of the city had dropped an average of 200 to 300 millimetres.
For some months the council had been working to better understand the extent of the damage and what needed to be done to protect properties from flooding.
Much of the work had focused on the Avon River catchment, but some investigations had been completed in the Styx and Heathcote catchments and in Sumner.
The investigations showed that of the 160,000 properties in Christchurch, 10,361 in the Avon, Styx and Heathcote catchments had the potential to flood in a 50-year rainfall event - 769 more than before the quakes.
Most of those properties were in already identified flood-management areas, but some were in adjoining areas not previously considered at risk of flooding.
"Each time the city has experienced a major [seismic] event, the land has been surveyed to ensure the council has a thorough understanding of what has been happening with the land," Mitchell said.
The Press understands that minimum floor levels in some areas are likely to change as a result of the data collected. They will come into effect immediately and could affect rebuilding plans and insurance.
Minimum floor levels of 11.8 metres above the Christchurch City datum have been in effect in flood management areas since January 2011, when variation 48 of the city plan became operative.
However, today's data release is likely to see requirements for floors to be built to that level, and possibly higher, in other areas that have sunk.
The existing flood-management areas are around the Styx, Avon and Heathcote rivers, in Lansdowne Valley and in some low-lying coastal areas, including Redcliffs and Sumner.
Reference: Lois Cairns
Check your own floor levels.
If your floor levels are out, it is likely that you have greater problems in your foundations that you need to know about and need to have fixed properly.
This is normally a major repair. In general (the building code allowance) if your floors are more than 23mm out they would need re-leveling. EQC states this to be 50mm.
This device gives you a cheap and easy way to get a quick indication of where you are at. If your floor levels are out by more than 23mm and you are being offered jack and pack type solutions or a cash payout you should get additional professional advice.
What you need:
Empty and clean the bottles.
Half fill with water and freeze
Drill holes for the grommets
Melt and drain the Ice.
Install the grommets
Plug in the hose, use tape if not perfectly sealed.
Half fill the bottles with water and some food colouring for clarity. Attach both rulers so they are identically placed according to water level. Place bottles on a different level and time how long they take to come up to level. Make sure lids are not sealed as air needs to get in for the water to level. The wider the hose the quicker they will level.
Draw and room plan of your house, place one bottle at the entrance and then the other in various places throughout the house recording the + – level on your plan.
Provided by Hugo Kristinsson.