I have been busy resuscitating Options 1 and 2 from my last post, and they are showing new signs of life. It’s amazing what desperation will do, and a good dose of CPR. If you have no idea what I am on about, read my previous post and if wall structure and condensation don’t thrill you then it’s best to move right along and wait for a more interesting post.
The months are ticking by, but I have been busy waiting on some more information from a few people before I get my final DA plans together. If you have never been “busy waiting” then you should try it, it happens a lot in Africa where you get stuck in queues for hours and can’t leave them in case you lose your spot. It looks like you’re not doing anything but you can’t leave or do anything else because you are in fact busy waiting. This feels just the same, I can’t move forward yet because I am waiting.
My bushfire consultant chased down the RFS over several weeks, as we were hoping to get them to look over the plans and provide some advice and maybe pre-approval. However, once he finally managed to speak to the RFS they weren’t really clear on the new NASH wall standards or other options for this type of build, and needed more details. I just confirmed with Council that the DA will go to the RFS anyway because it is BAL Flame Zone and will therefore incorporate an “alternative solution”. That involves not just the build structure but also the asset protection zone, position and set-back, dedicated fire fighting water tank and pump etc.
So it turns out there is not much point being busy waiting for any more RFS meetings in the hope of saving time and DA delays, when no time has been saved so far and the DA will contain all the full details they need to make a decision. Might as well have delays in the DA process now rather than wait some more to have them later.
I received a couple of quotes for INEX cladding, which as per my previous post now includes the bonus surprise of requiring rockwool insulation directly under it to pass BAL FZ compliance. The cladding and insulation has to be fitted to the outside of the container on-site, so it is not cheap but depending on the builder and labour costs it might still turn out to be the best option for the walls. I wonder if there is a DIY course on installing BAL FZ cladding. I am busy waiting to hear from the container builders, to see how much I can save if they omit the spray foam polyurethane insulation on the inside, which will never pass BAL FZ compliance anyway. They might also be able to pre-drill the holes for the battens to hold the cladding, as drilling corten steel would add to cladding labour costs.
There is some good news on condensation front. I spoke to a very helpful local architect, Ross Young, who sent me a wealth of information and explained the finer details of condensation. It’s all about water vapour and dew points, and my main query was whether having insulation on the outside of the build (under the INEX cladding) would be a problem for condensation. See the previous post for more details, but basically the container builders normally use spray foam on the inside to fill the corrugations in the container steel and reduce condensation risk.
As it turns out, it is actually better to have the insulation on the outside since the steel essentially forms a vapour impermeable membrane, and it’s better to have one of those on the warmer side of the wall, away from the cooler dew point. So ditching the spray foam on the inside and adding rockwool or similar on the outside is more costly but otherwise a good option – it will also make for thinner interior walls and save on interior space.
The roof is another issue; all of the approved BAL FZ roof systems are for normal shaped, gable type roofs with interior framing, eaves etc. The shipping containers are pretty tall (they are high cube containers) so I am still pondering the possibility of using the NASH wall system under the flat roof, working inwards from the steel. While this could work cost effectively for the Flame Zone issue, having insulation on the outside for walls and on the inside for the ceiling could be problematic for condensation. The other option is to continue the external wall structure using INEX and insulation over the roof. INEX comes in flooring /decking too, so should work for the rooftop deck.
Where do all the pesky condensation-seeking water vapours come from? Breathing, cooking, showering and generally just living. I am also looking into heat recovery ventilation systems, to just bash this condensation issue on the head. They are not looking very cheap so far, although there are some wall units available that are not as pricey as the fully ducted types which all benefit from having a proper traditional roof to install them in. I don’t want to add a proper gabled roof as it would get in the way of me sitting on top of the house for the view with a G&T, at least without needing a safety harness and a table with shorter legs on one side. And aside from the little luxuries adding a roof would also be a waste of materials and money.
The container home builder that I have been chatting to is away in China for a few more days, so I am hoping for some answers soon after he gets back.
I shall continue to be busy waiting. The feature photo here is a lovely Blue Mountains rock over a valley that is whited out with mist – unfortunately whenever I see any sort of water vapour now my thoughts turn to condensation…