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.
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!).
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!
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.
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.