So far so good

The picture above shows a fabulous design with a rooftop deck on a container house (from Pinterest via fantasticfrank.se). Take away the timber, and I am planning a similar rooftop deck on my house to take advantage of the gorgeous view. The back half of the house might also have a second story container on it, opening onto the rooftop deck. That top story might have to be scrapped if the new draft LEP comes in soon which restricts building height, since the height of the second story will be right near the limit pending the height of the foundations.  I’m really hoping I can squeeze that one container on top, the houses either side are both two story. More on the house design later.

Back to the progress update: I just had onsite meetings with an extremely helpful bushfire assessor, and a crane driver who clearly knows his stuff. Both went well. No surprises, the block is BAL Flame Zone; back, front and sides. Partly because of that, there is a good argument for building the house just where I would like it. There are the lovely established gardens and a sandstone retaining wall which it would be awful to ruin, plus the Flame Zone at the front of the block is out of my control as it is across the street, whereas I could maintain a firebreak on my land at the back (closer to the house). That will all become clearer when I post site maps, but for now it is hopeful news.

Container house by Meka with rooftop deck.
Container house by Meka with rooftop deck. Ditch the timber cladding, turn the top story container around and double its length so that it runs along the longest side of the house, and that’s the sort of deck I am aiming for. (From http://www.mekaworld.com)

Walls
For the steel clad walls, the bushfire assessor said that the new NASH standards will be adopted into the BCA (see previous post for background) so steel walls are potentially a viable BAL FZ solution. The plan of attack is to draft up some plans including steel clad wall structures, elevations and the landscape survey map showing vegetation etc, and go straight to the horse’s mouth so to speak – to see the Rural Fire Service in Glendenning and check if they would be happy with the proposed solutions. First though, I have to check if the approved wall structure is feasible in a container build.

Why is the RFS suddenly a horse? Because for a BAL FZ build, if anything out of the box comes up then Council sends the DA to the RFS for approval. And this container build is very much out of the box (excuse the pun!).

Windows
For the windows, I have good news. NSW is being very sensible about the astronomical cost of BAL FZ approved bushfire shutters and window systems, and is not forcing that cost onto us yet. So BAL FZ tested and approved windows and shutters are not required, as long you use the combination of 6mm toughened glass windows with metal frames, steel mesh screens over the opening portions, and then standard solid aluminium shutters (they have to be easy to close, with no gaps big enough to let embers in). I had one quote for BAL FZ approved windows, for what is going to be a small house, and it was over $20,000. So it’s a huge relief not to have to go in that direction. I am sure it is an even bigger relief for those rebuilding after the bushfires, who already face anything from $40,000 to $100,000 in extra costs due to the new BAL FZ regulations.

I have briefly looked into having the window shutters made out of the steel that is cut out of the container in order to create the windows. However, because the ease of manual closing of the shutters is so important (so you can race around and close them quickly if a fire front threatens), container steel shutters are unfamiliar/untested and might complicate RFS approvals. I would have to get an engineer to draw up the shutter design anyway, so it’s probably cheaper to go with standard aluminium shutters for now. But if anyone out there is already designing container steel shutters and getting them approved please let me know!

Container steel shutters
An example of window shutters that could be made for a container home. These are corrugated iron I think, but something similar from container steel might work. This solution looks to be out of the budget for now though. (Click on picture for source)

Roof
I also asked the bushfire assessor about the roof structure, as I would rather not add on a standard sloping roof – especially given the plans for a rooftop deck. Roof systems that have been tested to BAL FZ do not come cheap and it seems silly to have to add on another roof when I will already have one.

There are all sorts of structures in standard roofing systems that are potentially vulnerable to bushfires, like the fact the internal framework is normally timber, along with the eaves. A solid steel container box should be a better option in theory, so one avenue to venture down is looking at whether an approved wall structure could also be used as a roof. Flat walls, flat roof (with drainage of course). This would be the simplest solution.

Other options include cladding the flat roof in BAL FZ approved panels of which there are several, including INEX and Promatect 50, both of which do not require any additional layers to meet BAL FZ standards (like membrane and plasterboard). Neither are particularly cheap though and I would rather not have to add any unnecessary materials, to keep the build as green as possible.

Cranes
The containers need to be lifted in by crane, so this meeting was a quick feasibility check for access and the type of crane needed. There are a number of dead and sick looking gum trees to remove to give access, which should probably come out due to fire hazard anyway, and the hazard of falling on the house. They are all in the established garden rather than the native bush down the back of the block, and I am guessing that the garden fertilisers have probably done them in. I need to chat to Council about that side of things, but overall it looks pretty feasible for the moment.

There are nifty little cranes that can scoot under power lines and be jacked up so that they don’t squash the garden too much when they drive over bits of it. It’s all about reach with cranes (longer distance = less load) so if we can get the crane close enough a 50 tonne crane might do the trick.

Two more meetings down, no major obstructions to the build yet.

 

A little rainbow of hope

I haven’t found the pot of gold at the end of the rainbow yet, but I have at least found the start of the rainbow. External steel clad walls can exist in a Flame Zone. You may well ask, how can steel cladding and pretty rainbows be related? If you are not sure then you need to read my previous post first.

I heard back from NASH today (National Association of Steel-Framed Housing Inc) and they have new NASH Bushfire Standards coming out at the end of this month. There is a solution for using metal clad walls in BAL Flame Zone in it!

Little dance of joy.

Little. NSW Rural Fire Service don’t accept the NASH Standards for Flame Zone as a standalone, but might as part of a total solution – which according to NASH seems to mean that if you have water tanks dedicated for fire fighting, have AS 3959 rated windows and satisfy other aspects of the AS 3939 conditions, then the wall solution should be OK.

One key issue with steel in a BAL FZ is that steel is a conductor (although not as much as some other metals) so it would conduct some of the the radiant heat expected in the Flame Zone. There is potentially a LOT of radiant heat in a Flame Zone. The NASH solution therefore has a “thermal shield” in it, which going by the diagram looks like steel battens that create a small air gap between the steel and then an extra internal layer of plasterboard, creating a plasterboard sandwich on the inside of the steel (with insulation in the middle). A pic taken from the new NASH standards is below:

NASH steel clad wall solution in flame zone
NASH steel clad wall solution in flame zone

To me this looks a lot better than having to put plasterboard, membrane then fibre cement over the outside of the steel, and would have a smaller carbon footprint than all those extra layers. I am yet to cost it out.

I also don’t know how tricky or expensive this is to apply to a container build yet, as it has implications for insulation (normally spray foam) and also structure (achieving the gap between steel and floor frame for example). The full NASH document might include some other solutions, who knows. It’s a good start!

Thank you NASH. I had no idea you even existed until this week, but you are my favourite acronym now.

 

Steeling myself for yet more research

Sometimes it’s great when you are the first to do something, sometimes it is not. I am really hoping someone else has used steel walls in a BAL Flame Zone, in NSW.

I have spent many hours interrogating Lord Google and writing to steel production companies, design forums that promote steel cladding, and a few builders and architects. It seems that these days according to AS 3959, Superman should have been the man of fibre cement, or 90mm thick brick.

However, there is a bit of potentially, slightly good news at the end of this week’s investigations.

I was very excited to find this steel and shipping container building in what looks a lot like a BAL Flame Zone (pictured above). But, that was not the good news. My tail stopped wagging when I found out from the architect that it is a temporary structure so it didn’t have to have a DA. I have since found mention of another steel building in a BAL FZ in NSW, although it mentions fibre cement as well, so I am hoping to hear back from the builder or architect from that project.

Steel clad bush retreat in BLA FZ
Steel clad house in flame zone in NSW. Click on the pic to see the original article on this one.

 

Then I boldly ventured further into the world of bushfire industry acronyms and bureaucracy. The best news so far has come from the CSIRO. I came across a study that tested a steel building against the flame zone standards (AS 1530.8.2.) – the roof and floor did well, the walls needed a bit more work (doh!). Then I found a more recent conference paper that ran some more tests on steel walls, and I contacted the lead author at CSIRO who was really helpful. He said that “there are a number of new provisions relating to steel construction specified by the NASH building standard which have been recently adopted into the BCA”. This translates to the National Association of Steel-framed Housing, whose building standards have been taken up by the Building Code of Australia.

In short, with the right insulation and internal wall construction, he reckons it should be possible to achieve BAL FZ with steel walls.

That is where the real fun started – the BCA is not meant to be read by normal people. I got to page thirteen thousand and something only to find I did not have the right amendment version. There appear to be lots of amendment documents and they all come up on Google as “BCA 1996”, rather than the year of the actual amendment. I am assuming that the 13th Amendment didn’t happen in 1996, if so someone did a really bad job on the original BCA.

I think the new provisions happened in 2013 or more recently, so have been trying to find the correct bit of the BCA. Well, I’m not now, I’ve written to NASH instead, the BCA can go jump in the lake because I don’t have 200 hours a week to spend on this. I would rather be picking out nice colours for the interior…assuming there will be an exterior at some stage to keep them in.

The other potential cost blow-out is the BAL FZ windows, which may require extremely expensive kryptonite-resistant glass and shutters. However, I found a helpful forum which seems to suggest that in NSW there is an exclusion on Clauses (e) and (f) of 3.7 in AS 3959. “Yipeeee” I thought, not knowing what the heck that meant but liking the sound of exclusions. What it means is that using BAL 40 twice (windows and shutters) might equal BAL FZ. More on that later. I am meeting a bushfire assessment consultant on site later this week and have a growing list of questions that I hope he can answer…

Just to clarify, it’ll be a house not an oven

I realised I haven’t given many details yet – so before someone sensible points out that you can’t just dump a container on a block and live in it “because it will get hot” – I thought I should say that this is a proper build in the making. It will be fully insulated to normal housing standards, lined with plasterboard, plumbed and wired to Australian Building Standards etc.

If you’d like to see an example of a seriously stylish container build, check out this link, the photo above is from a design by Benjamin Garcia Saxe. This is one design that I am considering as a base, along with a couple of others.

To clad or not to clad, that is the question

Right now I am on a learning curve and in discussions with container home builders for the structural part of the build, structural engineers for foundations, and crane drivers for feasibility of delivering containers to the part of the block I want the house on. But that is all side issue stuff for now, the real meat in the sandwich is the bushfire assessment. The site is at the very top of a steep forested gully, which makes it a ring in for Bushfire Attack Level Flame Zone (BAL FZ) – the nastiest classification you can have. Well done me. I guess that comes with a lovely block in the middle of the bush with a bit of a view.

So the important conversations are with Bushfire Assessment consultants. There is a lot to consider to comply with AS 3959 – it’s pretty scary that I can already write that Australian Standard down without having to look up the number, along with AS 1530.8.2 (and if you’re after general FZ information it starts on page 74 of AS 3959).

One of the most challenging issues so far is the corten steel walls that come with shipping containers. This is strong stuff, built for being at sea for 25 years or so and taking a battering. Container builders say it’s fire proof, which is logical being steel and all, but for BAL FZ that’s not enough; materials either have to be non-combustible and 90mm thick, or have a Flame Resistance Level (FRL) of 30/30/30, or comply with AS 1530.8.2  – which involves someone spending a huge amount of money for CSIRO laboratory testing of the material when exposed to incredibly high temperatures and flames. No-one has tested corten steel. Blue Scope steel says that no steel is ever fire tested and it’s all about having steel as part of a wall system, but they only have a tested “system” for roofs, not walls.

Blue Mountains City Council have been very helpful so far, and I have a copy of an approved DA for another container home in the area that has not been built yet. That one is clad in a fibre cement system, in fact it has three layers outside of the corten steel – special 16mm fire resistant plasterboard, membrane then 6mm fibre cement sheets.

Understandably Council says that someone needs to put their money where their mouth is and prove that corten meets some sort of building standard. Steels are not all alike, and many a shed has buckled under a bushfire – integrity after a fire as well as flame resistance is part of the rating system. So I am trying to find any information that will support using steel panels, corten alone or even with weathered steel cladding over it, as the outer part of an external wall in BAL FZ.

 

The soil test

The soil test is essential but pretty boring so I put another photo of the Blue Mountains here, instead of a 4WD with a small drill rig on the back. The picture shows the sort of mountain mist that is likely to surround my house for much of the year. If you would like to see pictures of soil there is some on the bottom of my boots in the photo 🙂

The reason there is a lovely garden on the block is that it is a subdivision. So one thing I had to check was the Site Classification – which involves a soil test to look at potential for expansion and reactivity of the soil, and determines what sort of foundation you can have for your building. It’s a good idea to get this done first up, mine was included as clause in the contract to buy the land; if the test came back as a huge problem I would be land hunting again very soon.

The test came back as Class P for problem site, which gave me a brief heart attack. I was expecting Class A since it’s nice and sandy, but in this case there is too much sandy infill. Anyway, apparently 70% of sites in Australia are Class P, and it’s not necessarily a big deal. Time to take a deep breath and relax. I am not using a concrete slab foundation, and I sent my soil test report to a structural engineer who said for concrete or steel piers there is no issue. So I’m still good to go with the build.

So the budget blowout will not come from the foundations – it might well still come from the Flame Zone building regulations but there’s plenty of time to worry about that.

It starts with a site

OK so the picture above is not the site. But it does show the ridgeline that the site is on, from the valley below, to give some perspective because it is a stunning place. This gorgeous bit of the Blue Mountains has inspired the project. The objective is to create a shipping container home, customised to this lovely location, and to do it mortgage free! The first challenge is that the site will most likely be classed as BAL Flame Zone, so the build will have to fit very strict Australian standards for bushfire areas. Surely, starting with steel boxes has to be a good thing…

This will not be a fancy 13 container, architect-built project, it’s a simple two to three container project aimed at creating a cosy mountain home that is easy to heat and cool and has a small footprint. So if you are after fancy there are lots of other websites to look at, this is about documenting the process and all that it entails. It may be painful at times.

Small stone paths wind through the garden.
Small stone paths wind through the garden.
garden bench for sitting in the sun in winter
There is even a bench for sitting in the sun in winter.

winding path to driveway

House site with gully view
The house site overlooking a bush gully.
House site with happy owner on it.
A happy land owner. This may be the house site, depending on the bushfire assessment and where I am allowed to put it.
House site from the valley below
The house is up on that Blue Mountains ridgeline somewhere.