How to create an earthquake resistant house

Recent shots from the aftermath of the Kaikoura/Culverden earthquakes in NZ 2016. Photo Credits and Copyrights in order of appearance: Richard Bicknell; RNZ/Alex Perrottet; RNZ/Rebekah Parsons-King; TVNZ

Your home is your castle, your fortress, your safe haven. So what happens when the walls start falling down around you? The ceiling caves in? It shifts off its foundations? What happens when your home is no longer keeping you and your family safe? 

In this post we explore the concept of creating an earthquake-resistant house and the birth of the vision for a home that cares for not only the environment, your health and your finances, but also your life when threatened by crisis. First and foremost though, our hearts go out to anyone who suffered during this recent quake, because we know first hand what it's like to have your world turned upside down by mother nature. Kia kaha to you all.

How destruction happens in a quake

How can a house shift from it's foundations or crumble to dust in a strong earthquake? It really comes down to one reason: anything that is fixed to the ground can and will eventually have its structural integrity compromised when the earth shifts.

If you've ever been in your vehicle or watched cars on the street during an earthquake or strong winds, you'll notice that they move about with the waves, not against them. The reason being, the vehicles are moving independently from the ground and therefore are not put under stress and strain to resist the force coming at them. If you imagine a house in the same situation, able to move independently and with some flexibility from the ground, rather than being fixed so rigidly that the force of an earthquake rips it from its foundations, then you have an earthquake resistant house.

After the 2010 and 2011 earthquakes in Christchurch, NZ, many of us saw the destruction caused, we felt the fear of our homes caving in on us and crumbling down around us. I was in a double-brick home, my family home, as it fell apart, cracked open like a wailing wound, and liquefaction filled the back yard and driveway. The fear I felt was that it was no longer safe to be indoors, in this house "built like a fortress", as my father would say. Outside, the roads opened up, warped, bubbled and was like a war zone, and it was terrifying. 

We didn't go back inside other than to collect a few belongings. Shutting the doors knowing we probably wouldn't be back. That was the longest week of my life and the one that left us with such uncertainty of the future.

Paul, being a project manager for an architectural building firm at the time, recounted that it didn't matter how deep, how strong, how expensive the foundations of his big homes on the hill were, they may have even been perfectly intact after it all, but the houses? They were all destroyed. Not one of them survived unscathed. That was the catalyst and birthplace for Park Homes' signature floating foundation.

What's a floating foundation?

Whilst I won't go into too much detail here (this is, after all, our signature structure and own innovation!), in a nutshell, a floating foundation is the structurally engineered frame which forms the base of a Park Home, whether that home is a single module or multiple modules put together. What this allows the house to do in the event of an earthquake, is to sit atop the ground and move freely with the forces, rather than against them. Sometimes people ask if the house will shift or move like Dorothy's home in the Wizard of Oz - the answer is NO! Of course, it is still a house, even a lightweight one at that, but a house that has weight, downward force and lateral restraining pads keeping it in place.

Even if the Park Home is to be built on a hill or in a high wind zone and therefore requires a traditional foundation of sorts (say piles, for instance), and thus has to be fixed to the ground, its design is such that it maintains some level of flexibility and thus is less likely to compromise the integrity of the house when it moves in an earthquake.

How does a Park Home perform in a major earthquake?

So you may be wondering what happened, what it felt like, what the damage was, after this major 7.8M quake? I can tell you straight that the home performed as it was designed to: with the waves, rocking gently rather than shaking and jumping wildly. There were no cracks in the walls, there wasn't even one household item out of place. I must say, in the two major quakes (Valentine's Day quake 2016 and Kaikoura quakes 2016) and multiple aftershocks that I've experienced in this Park Home, I've never felt safer.

I'd love to see more families feeling safe and protected in their homes when disaster strikes, and I'd also love to see Park Homes helicoptered over to the folks in Kaikoura who've been hit the hardest! Maybe the NZ government could take us on as a rehousing project? I'm sure the NZ Army helicopters could lift one of these babies in a heartbeat :-)

Take care out there people!