For those of you who have laboured through the last few torturous posts on wall structure and cladding options, it’s time to breathe easy, I have some good news. A new solution has popped up. Popped up in the way that things pop up when you spend months dredging the internet for options, I guess it was more wrangled out of the cyberspace abyss.
I came across this option earlier but that was in the days when I thought spray foam insulation was the only option for containers, so I was ignoring a lot of the multi-layer external cladding options.
Builders out there are probably familiar with it, it’s magnesium oxide board – very green, almost carbon neutral, fire proof, rot resistant and termite proof. Now that is the personal profile I have been looking for in a cladding option, I could fall for this one. Oh and one more vital personality trait, because I am such a classy gal, it’s cheap!
Less than half the price of INEX weatherboard in fact, and it looks to be less fussy with the wall system you need behind it to meet BAL FZ compliance. Plus it’s manufactured in big sheets and would be much quicker to fit than individual weatherboards, so less costly in terms of labour. I discovered INEX does do a renderboard which would also be quicker to apply, but you have to then render it which would probably chew up any savings. This magic MgO board only needs a coat of paint. It complies with BAL FZ through the FRL option, of having flame resistance level of 30/30/30 or more – typically this stuff is at least 60/60/60 or more.
There are a bunch of different magnesium oxide (MgO) boards and structural insulated panels available, some with dubious qualities as they are all made in China. There appear to be two here that are certified to BCA standards and have sufficient details on bushfire qualities – MgOBoard and Modak. Modak also do a very cleverly designed gutter that removes the accumulation of leaf litter and so reduces bushfire risk.
From the specs it looks like the board just needs to be fitted to an external wall with some decent insulation under it, no special plasterboard as part of the wall system. If there is no need for plasterboard then I might even be able to have some container steel showing on the inside of the house, which would be great to expose the bones of the house.
I did hear back from the container home builders and they are not real keen on the NASH wall system – they do builds at low cost by making them all the same, so a whole new system would not be easy or cheap for them. They suggested I get the wall system fitted once the containers are on site, but there are more layers and labour involved in that than just adding battens, insulation and cladding to the outside. And now that I know that insulation on the outside is actually a good thing, not a bad thing, together with the fact thinner walls in the inside will give me more space, the exterior cladding option is looking like the best for me.
For anyone out there creating more space with more containers, and who has the time and skills to add interior walls, NASH steel clad walls for BAL FZ could still be a good option – as of this month the standards have been adopted into the National Construction Code.
I am meeting with my bushfire assessor this week, to look at running with the MgO board and getting the final documents together for my DA. Whoop whoop!
There is still the small issue of the roof, but once the rooftop deck is on (which could be MgO or INEX) there is only a small amount of actual roof left (one container at 28 square meters) so it should not be a big deal to whack on something BAL FZ compliant. MgO do some roofing products as well. Or maybe I could have a split level rooftop deck and no roof…