Hi guys,
I'm in the process of designing a building similar to the one you guys are building.
I notice you went with steel construction with Plycem. Most contractors here are recommending concrete block as they are better for earthquakes. Also, most of the labor force knows how to work with block. Just wondering about the thought process that you went through to choose the material and problems you encountered.
Thanks
Hola Jon,
Congrats on starting your own build, I hope we are able to assist you. I have 2 thoughts on this but by no means am I a professional or expert in the field so I would listen to the advice of the contractors you are using. I also welcome opinions from others so we can maybe all help each other out and others that may read this.
Firstly, concrete block was not an option as the community we built (and live) in, has certain building requirements/restrictions (which we are in favor of). One of them is to have the house elevated in order to have minimal impact on the environment, this left us with 2 options - wood or steel. For those interested, we also do not cut any trees down and build around them.
Secondly, in my own research attempts, I was left with an impression that steel is a much better building material for earthquakes than concrete blocks. Taken from a steel construction fact sheet:
"Steel structures are lighter and more flexible than concrete structures. As earthquake forces are associated with inertia, they are related to the mass of the structure and therefore reducing the mass inevitably leads to lower seismic design forces. Indeed some steel structures are sufficiently light that seismic design is not critical. A typical, multi-storey steel-framed building is 60-70% lighter than an equivalent concrete framed building. Although steel is strong, it is also flexible. Flexibility is one of the most important aspects of buildings in areas that are prone to earthquakes. The flexibility of steel allows a building to survive moderate seismic activity easily without sustaining any real structural damage."
(I like to imagine the structure similar to that of a tree, they are flexible and not falling down everytime there is an earthquake)
We have experienced several earthquakes whilst living in the home, the highest recorded being a 6.5 and the house did very well, it certainly shaked more at the top than it did at the bottom but the flexibility helped anything from breaking or cracking. It's certainly not a nice feeling (Amy especially doesn't like it) but I'd rather it was flexible than stiff - again, this is personal preference and I am not an expert on the subject by any means.
We used galvanized steel for extra strength and protection as well as having a structural engineer review our plans:
We also connected all the foundations underground for extra reassurance:
And added extra reinforcing where possible:
Overall, I found that the steel went up quick and if you have some competent wielders, then I can't see why concrete block building would be any quicker or easier. We experienced no problems using the steel and overall are very happy.
In closing, the house will shake during an earthquake and probably more so than a concrete block construction - in my opinion I would rather have a house that's a little flexible but overall it comes down to personal preference.
If anyone reading this has experience with building in concrete block or better yet, has experience in both concrete and steel when it comes to earthquakes - please share your thoughts below.
Good luck with the build Jon and please keep us updated!
Matt