Enough with the shipping containers!
If there’s one thing that I can’t stand in modern ‘trenditecture’, it’s the obsession with adaptive reuse without considering if what you’re doing is actually sustainable reuse. There’s a lot of things out there that end up being more wasteful when reusing, and often you’re not getting the green credentials that you think you are.
Nothing in this day and age that I’ve come across in architecture exemplifies this more than shipping container architecture.
Don’t get me wrong, there are some great examples of container architecture that look good and serve a functional purpose, but there’s also a lot that just wasn’t worth the effort.
A pretty good example of reuse.
So why do I not like shipping container architecture?
Well I actually do like the idea. Just not for homes. The image above from Christchurch shows architecture that responded to a very real need to get the CBD up and running after the 2011 earthquake. With nearly 70% of shops, hotels, and offices gone in the aftermath, something had to be done.
But many architects and builders are spruiking container architecture as some kind of ‘ultimate’ solution to the plague of old shipping containers (a very real problem by the way) and the shortage of affordable homes. After all, if you’re recycling materials, it HAS to be cheaper, right?
Well yes, but actually no.
There are a lot of things that are left unsaid when selling container architecture, and this lack of information helps propagate the myth that it’s a good idea for housing.
We can look at a lot of issues, but let’s break it down into some distinct categories.
Structure
Durability
Safety of Users
Energy Efficiency
Structure
So your basic shipping container consists of a portal frame and some specialised corner mouldings. This portal frame is not particularly robust on its own and would easily deform under minimal load. So what to do? Well, the engineers who designed the shipping container, way back in the day, decided to stiffen the walls with a nifty trapezoidal steel profile. In practice, this is pretty similar to how a timber i-joist works, with its fairly thin plywood/OSB web. Very cool application of structural engineering, and I’ve got to hand it to the guys who came up with the original design - fantastic job.
Those top rails aren’t supporting much without the sidewall panels helping.
The point is, this trapezoidal wall is actually quite integral to the structure, and removing it for annoying things like natural light compromises the structural integrity. Not worry though, because now you get to put in additional expensive beams and columns to make up for what you’ve removed!
Another thing to bear in mind is that the standard ISO shipping container has questionable internal dimensions compared to the standard home. Width is a mere 2.350m (internally), with a ceiling height of 2.390m (also internally). Sure, you could get a high cube container for a 2.708m ceiling (internally), but these aren’t as common and would therefore be a bit more expensive. That gets smaller again once you add in strapping and lining, unless you really want to look at industrial steel (not judging - it’s a look that can work well, but most people aren’t up for that).
Because of that internal width, most people are going to want a double width space, especially for their lounge, dining, or other entertainment areas. You now have to take out an entire wall and put two containers side by side, but again - that portal is not made to take any real loading without that wall. Time to add in another beam!
Durability
You’d think these things would be pretty durable considering they spend a good deal of time at sea, dealing with extreme amounts of salty air. But the engineering behind shipping containers is based on a 10-12 year lifespan. So it’s to be expected that any shipping container that is being recycled (i.e. has reached the end of its lifespan) would need to be treated again to prevent rust. Building a house assumes a structural design life of fifty years in Australia and New Zealand. Keep this in mind for later when I discuss safety.
Fine for intended use, not so much for housing people.
Safety Of Users
Shipping containers get to transport all kinds of neat things throughout their life, including carcinogens, toxins, and other goodies that would kill you very quickly in large doses. Thankfully, in small doses these things only kill you slowly.
If you are inclined to not let your house kill you (which is admittedly a controversial take but we’ll allow it for this thought experiment) then you will need to let professionals do a thorough clean of the internal (and external) of the container. More than likely you will need to have the container professionally sand blasted, and tying back into durability this will need to be SA 2.5 (to AS/NZS 1627.4) so that you can immediately coat the steel surface with an appropriate level of protection.
Energy Efficiency
…and thermal performance.
Surprisingly, living in a big metal box without adequate insulation is a recipe for disaster. Extra cold in the winter from heat loss, and extra hot in the summer from heat gain. Insulating the box is not a super difficult task, and utilising ‘outsulation’ (which I’ll discuss in a future post) will help. But a big concern then is ensuring that you won’t have condensation issues, and using a big solid metal box with limited airflow makes things unnecessarily complicated.
Just don’t try and insulate between the ribs.
No, no, no! Think of the bridging! Think of the condensation!
In addition, putting in HVAC systems, which are a must in modern housing (passive design alone doesn’t work*, don’t @ me) need to be installed with limited head room or by penetrating that structural wall.
Well what can I do instead?
There are many excellent steel fabricators all across Australia and New Zealand who could make a portal system that can hold itself up and would be a better use of resources. These can even be engineered to incorporate portability or be factory built like a more traditional modular home.
Something I didn’t touch on was whether or not recycling a container was even efficient use of resources. Putting something into a house as a structural element ties up that material for 50 years in theory, more again in practice. A shipping container has enough steel in it to build 10-15x as many similar sized houses if you were to melt it down and use it to make lightweight steel studs.
Not super green if you ask me.
Drop us a line or email, and we can talk you through better structural options that give you greater flexibility, cost less, and are far more sustainable.
*Passive design is not the same as Passive House (or Passivhaus) which does work exceptionally well.