Please note masks must be worn at all times in our show homes and you will need to either sign in, or scan the Covid QR code with your phone. Numbers permitted inside at the same time are limited under Level 2, so if you want to avoid waiting you might like to try to visit during weekdays which are less busy. Thanks and see you soon 🙂

Earthquake resistant homes

Earthquake resistant homes from our Solid Timber range in particular, performed exceptionally well during the Christchurch earthquakes of 2011, and the Kaikoura earthquakes of 2016.

Put to the test in the Christchurch and Kaikoura earthquakes

In one instance, one of our Solid Timber homes remained completely unscathed following the 7.8 earthquake in Waiau near Kaikoura, despite the home being positioned 100 metres from the fault line. Many other homes and buildings in the same small town were decimated and in ruins. The location of the fault had been hitherto unknown to geologists and engineers.

Watch the amazing footage of that Waiau home the day after the earthquake, and the happy homeowner here (footage courtesy of the New Zealand Herald):

 

 

We regularly have owners of our Solid Timber homes contact us or write public reviews saying how safe they felt in their homes during the earthquakes. Here are a few:

“The best earthquake proof house – it handled the 7.8 no problems. I’d recommend to anyone going to build. Cheers Fraemohs.”

“Hi, not sure if this is of interest to the design team at Fraemohs but we have a 35 year old Fraemohs house on piles near Waiau so wanted to let you know that we are delighted to report no earthquake damage. The house coped very well with a huge shake.”

“I was in Hanmer in a wooden Fraemohs chalet trying to fix my phone while my wife watched a TV movie when the first big 7.5 hit. I have to say the chalet was great – strong as a boat in a storm as we rocked and rolled. It was built on a good thick concrete pad and the interlocking beam walls performed perfectly.”

“The house just rattle and rolled and then settled back into position again.”

“I live in a Fraemohs home in Spencerville and after 3 major earthquakes we have had no damage. Thanks Fraemohs for keeping my family safe.”

“Just a couple of kilometres up the road virtually an entire subdivision got ruined by the earthquakes – but our Fraemohs didn’t even require repairs. The only thing on our property to suffer damage was the driveway!”

“We have just moved to a property with a 70s original Fraemohs house – it rolled with the quake but we still felt safe – unlike the Chch house that broke apart in Feb 11.”

“Thanks Fraemohs, I feel safe in my home”

“Our 1981 Fraemohs home on poles in Mt Pleasant Chch had no damage requiring repair other than a hot water cylinder. Recommend!”

An engineering perspective

The following is an excerpt from a report titled Performance Of Houses During The Christchurch Earthquakes of 22 February 2011 by Andrew Buchanan, David Carradine and Hugh Morris for The New Zealand Society for Earthquake Engineering Inc:

“While these buildings were reported to have moved significantly during the earthquake, the damage observed after the event was minimal, even in cases where significant ground settlement (up to 200 mm) was observed. It was noted that for Fraemohs houses built using 63mm thick (2 and 3 laminates) walls, there were some cases where small portions of the timber sections had sheared off near the bottoms of walls, as shown in Figure 43. This was reported to be the most severe damage to any of the inspected Fraemohs homes and it was noted that the failures occurred in places where the laminates were half notched, therefore having a smaller cross section.

No damage was observed in Fraemohs homes made using 93 mm thick, 3 ply laminates. A Fraemohs house located in the Avondale area of Christchurch was found to have only minimal separation of some of the log/timber courses even though the house suffered differential settlements up to 100 mm, cracking of the concrete floor slab, and severe liquefaction resulting in several tonnes of silt needing to be removed from inside the house and from the surrounding yard.”

Low damage design

Locally, some insurers have become reluctant to insure a lot of New Zealand’s building stock because of the cost of remediation after a major event, making it increasingly expensive or impossible to get cover. Some insurers are threatening to pull out of the New Zealand market altogether.

 

A shift in thinking…

In this context, we are seeing a shift in focus around seismic design. Historically, we’ve rightly focussed on life-safety; aiming to prevent a catastrophic collapse by designing the building to yield (sustain damage) in a controlled manner during a large seismic event, enabling everyone inside to evacuate. While this limits loss of life, it is often difficult or impossible to repair this damage. This contributes to the enormous rebuild costs, jittery insurers, and stressful relocations for families and businesses.

Clearly, we need our buildings to remain serviceable where possible after a major earthquake. The construction industry is starting to respond to this, with engineers and architects employing “low-damage design” principles in their new buildings. For commercial buildings, there are a number of strategies available to increase building resilience, such as:

  • Making the building so strong that the design limit is never reached, even in the largest anticipated event. Sounds obvious, doesn’t it? Unfortunately, the cost of this is so great that it is prohibitive for all but the most essential structures, such as hospitals and significant civic buildings.
  • Protecting a building’s structure in a significant event by using base isolators. These prevent the most significant forces from the ground from being transferred into the structure.
  • Dispersing the shaking energy throughout the entire structure and dissipating it in specially designed dampers at joints between structural elements. If there is any yielding during a seismic event, it is concentrated in these elements. They are specifically designed to be easy and inexpensive to replace so the building remains functional or can be put back into service very quickly.

Even better today

As the above excerpt shows, despite being subject to serious movement of the ground and supporting foundations, Fraemohs Homes suffered only minimal damage. This damage was observed only in those homes with 63mm thick walls. As a result, we now use 100mm thick 3 ply external walls and 60mm thick internal walls as standard so our current homes are even more earthquake resistant.

 

Protect what you hold dear

Building a home from our Solid Timber or Transportables range could be the best decision you ever make