Making your foundations earthquake ready is one of a number of things to do around your home to help prevent damage and injury from an earthquake.
Foundations are the primary connection between the ground and the building so they bear the brunt of an earthquake’s energy. If your foundations aren’t in good order, your house may slide from its foundations or topple in an earthquake.
Many foundation systems consist of concrete or timber piles. These act as a structural support for the house. It’s important to check the foundations of your home are earthquake-ready and that you take any necessary steps to put them right.
Things to check
- Are the piles in good condition?
- Is the house properly tied to its piles?
- Are the piles properly supported with bracing?
If you decide to inspect the foundations yourself, make sure you do so safely:
- Ask someone to stand by while you’re underneath
- Make sure they know which areas you will be working in under the house.
- Make sure any power and gas services are safe to work around.
- Wear the appropriate gear for the task such as overalls and boots.
You should not go under your house if you believe the foundations to your house have been compromised or pose a health and safety risk. If in doubt, get a building professional to check the foundations for you – they know what to look for and will be familiar with how to do an inspection safely.
- The piles are standing upright
- The piles are evenly supporting the bearers
- Timber piles show no signs of rot or borer
- Concrete piles show no signs of cracking or crumbling.
- The piles are not exposed by ground excavation or due to being too close to the top of a bank.
Piles that are damaged, misaligned or undermined need to be repaired or replaced. This isn’t an easy task, so get advice from a building professional.
- The connections between the bearers and the piles are in good condition (not loose, rusted or broken)
- The connections between the bearers and the joists are in good condition (not loose, rusted or broken)
Special fixings are available from building suppliers that can be fitted to existing concrete and timber piles. Concrete piles can be tied to the bearers using fasteners and galvanised wire threaded through a hole in the piles.
Use fittings that are suitable for the environment in which your house is located (e.g. coastal). If in doubt, it is strongly recommended that you seek advice from a building professional.
To find out more, watch our video.
Bracing includes diagonal timber bracing (between the pile and bearers or joists) and perimeter walls, which are outside the perimeter of the foundations.
- The concrete perimeter foundation walls show no signs of cracking or crumbling.
- The timber framing is still adequately connected to the wall.
- Any fasteners are still in good condition (not loose, rusty or broken).
A building professional will be able to advise if your house has adequate bracing. A chartered professional engineer can design the right bracing solution for your house.