![]() ![]() ![]() ![]() The location and accessibility of services needs to be taken into account. Liquefaction ejection results in soil loss and is a primary mechanism of ground deformation.į. This principle is followed particularly with the shallow surface solutions and for service trenches where possible. Minimising penetrations of the crust (the ground between the surface and the layer that is likely to liquefy) will reduce the likelihood of liquefaction ejection coming to the surface. Instead, separate the two structures with a seismic gap.Į. (eg, Type 1 timber floor house and attached concrete slab garage). Mixed foundation systems within the same structure are not recommended. The ratio of the projected dimension divided by the length of the side in common should be no greater than 1.ĭ. Any number of minor projections (ie, 2m or less) are permitted off the base shape, or off the major projection.The ratio of the projected dimension divided by the length of the side in common with the base shape should be no greater than 1. (This might result in an ‘L’, ‘T’ or ‘V’ shape base plan). One major projection (ie, greater than 2m out from the base shape) is permitted.A base plan shape that is essentially rectangular with an aspect ratio no greater than 2:1.Regular structural plan shapes are preferable to more complex plan shapes.Ī regular house plan is defined as meeting three basic criteria: A slip layer beneath shallow foundations or foundation slabs will improve the performance against lateral spreading (stretch) at the surface.Ĭ. Stiffened and tied together foundation solutions are required to improve resistance to lateral stretch and ground deformation. This is to reduce the inertial loading on foundations and the potential for settlement in future seismic events.ī. Light-weight materials should be used for all roof and wall claddings. The following design principles should be used to design resilient foundations in adverse ground conditions:Ī. This approach is an alternative solution in the hierarchy of the Building Act and has no place in the design of High Performance Homes as it does not conform to the “no repair required” criteria above. ![]() Refer MBIE Table 8.1 for further information. Note that care should be taken when using the solutions directly from the MBIE guidance as their design premise is based on the concept of “readily repairable”. Repairing and Rebuilding Houses Affected by the Canterbury Earthquakes, otherwise colloquially known as the MBIE Guidance is the only document available for design reference in New Zealand. If fixed to the reinforcing mesh the slab must be at least 125mm thick.įrom a structural point of view, it is better that the heating is fixed to the polystyrene, if that’s the insulation surface especially if the reinforcing has a structural purpose or is being used to resist cracking in a polished concrete floor.ĭesigning Foundations in Ground Affected by Seismic Events Note that if in-slab heating is to be installed, either the heating pipe is installed on the polystyrene on the underside of the slab, or fixed to the reinforcing mesh. If the ground is not prone to differential movement then the foundation is unlikely to settle. The primary difference between foundations designed for minimum standard homes and those designed to the Healthy Homes Design Guide requirements is that the foundations for Healthy Homes are all required to be insulated.Īny of the foundation solutions outlined in NZS3604:2011 are suitable. ![]()
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