If you decide to go under your house, make sure you do this safely.

Different parts and fastenings of a suspended floor foundation
Are the piles in good condition?
You can make some basic checks under your house for signs that could indicate a foundation problem. Some things to look for include:
- piles on a tilt or not standing upright
- piles unevenly supporting the bearers, possibly with gaps
- timber piles, bearers and joists showing signs of rot or borer
- concrete piles showing signs of cracking or crumbling
- piles exposed by ground excavation or slips
- where piles are missing, or other objects have been used to support joists or bearers.
Piles should be firmly embedded in the soil without gaps around their bases. Piles that are damaged, misaligned or missing need to be repaired or replaced. These aren’t easy tasks, so get advice or help from a licensed building professional.
Is the house properly connected to the piles?
Piles that are well connected to a house will help minimise movement and damage during an earthquake and some other natural disasters.
Check that connections are in good condition (not loose, rusted, broken or missing) between:
- bearers and piles
- bearers and joists.
If the piles are not sufficiently connected to the bearers, special fixings such as Z-nails that are made specifically for this purpose, wire, bolt or bracket bearers (all available from building suppliers) can be fitted to existing concrete or timber piles and bearers.
Be sure to use fittings suitable for your house’s environment. For example, any steel connections within 600mm of the cleared ground level need to be a minimum of type 304 stainless steel.
For detailed information on fixings, see the Foundation and Subfloor section of the NZS 3604 Standard for Timber-framed buildings and, if in doubt, contact a licensed building professional.
Are the piles supported by bracing?
Piles need support to prevent them tilting in an earthquake. Bracing can provide the piles with support. Seek advice on bracing from a licensed building practitioner or engineer, particularly if your home has either:
- a concrete perimeter foundation wall that is not continuous
- a subfloor more than 600mm above ground (especially one with pole foundations).
If necessary, a chartered professional engineer could design the right bracing solution for your house. Installing bracing is a job for a building expert.
If your house has bracing, you can complete a basic bracing review by checking that:
- any timber framing is still adequately connected to the wall and not damaged
- any fasteners are in good condition (not loose, rusty, broken or missing)
- if you have a concrete perimeter foundation wall, there are no signs of cracking or crumbling.
Download free technical guidance on repairing and rebuilding houses affected by the Canterbury earthquakes from MBIE’s building website – foundations are covered in Part A.