Walls for BAL FZ

Hi All,

I am planning to do a knock down rebuild in a BAL FZ site and in need of advice around the best way to meet standards for external walls.

The AS 3959-2018 indicate that for walls I basically have four options,

1. Non-comubstible material (Full masonry, Masonry veneer, concrete etc) with min. thickness of 90mm OR
2. System that conforms with AS 1530.8.2 when test from outside OR
3. System with an FRL 30/30/30 or 0/30/30 tested from outside OR
4. combination of any items above.

I am looking to build from ICF and this is expected to meet the standard requirements, however seeking advice around the ability to meet the standard with certain finishes for example,

•ICF + CFC glued, screwed
•ICF + batten and CFC system
•ICF + rendered
•ICF + veneer stone cladding
•ICF + Metal sheet

Need to understand if I use the above finishes would I not meet the requirement despite my underlying wall structure meeting the standard requirements.

I Would also be interested to understand how the 4th options can be interpreted, i.e. when the standards says combination of system. What can this look like?

Any help will be much appeciated.

Thanks
Loch

I suggest you consult a fire engineer OT there's no appetite for engineers to assist
BTW, polystyrene has pretty much been banned on class 2 buildings already..Here yet another Grenfell case lurking
Cladding protest after fire at New Providence Wharf in east London

Durisol ICF + rendered can go all the way to 180/180/180

Alex and Chris who have already commented are both incredibly intelligent guys in their respective fields and have give you some good advice.

Chris is spot on though, get yourself a good fire engineer as the roofing is probably the most technical aspect of your build to get right for the FZ zone.

We are doing a number of FZ builds in Sydney. I know Alex loves his Durisol but I tried to buy some recently on Alex's recommendation, and they wouldn't sell me any unless I guaranteed to install triple glazed windows which was way over the top and unaffordable for a client.

I actually had a debate with the rep and he agreed that core filled block work was cheaper and just as energy efficient as Durisol ( and there is none in Australia as of a few weeks ago).

The rep actually told me that a guy was building a $10m waterfront home in Sydney and he had a greed to use triple glazing on all windows bar one that had the best water views and they refused to sell him any product. The rep was proud of this, wouldnt even accept double glazing. I am sure the product is good for those who can afford it but boy its expensive when compared to alternatives.

Anyway, that aside good luck with your build. Happy to recommend a really good fire engineer or bushfire consultant as you will need one

cheers

Simeon

Thanks Gents! I do appreciate the responses. I am based in Epping NSW, FZ zoning is bit of an overkill for my site even agreed by my Bushfire consultant unfortunately the rules are not area specific.

To Chris, I am trying to avoid exactly that by doing some good research and getting proper advice before I submit CC and DA.

To Alex,
I have heard on this forum that Durisol is quite expensive, I was thinking more Zego or Eco block. I know people who have used it and they are coming back with potentially 5 to 10% more than BV. Both brands have products that have been tested to comply with FZ. Do you have any insight on those two brands?

To Simeon, Will look more closely into the point you raised on the roof.

I am trying to stay away from build system that require heavy labour, hard to manage and quality of workmanship is a challenge. Hence my preference towards ICF provided you get experienced contractors to do the work. I did noticed an earlier post by you on pricing, very insighful.

Windows - I am highly likely to go with double glazed + 6mm toughened glass + Fire shutters on Windows.

I already have a bushfire consultant who I can go for advice, should I be engaging and engineer to give formal advice on roof, wall and windows.

What time up external wall systems would you recommend for BAL FZ? Are you suggesting to stay away from ICF despite zego and eco-block having products that meet requirement.
And do you recommend any particualr roof systems brands for BAL FZ.

I am also keen to get your fire engineers contacts if that's okay.

Thanks,
Loch

Hi Loch

We are based at West Pymble and seem to be picking up a number of FZ homes around Pymble and St Ives as a lot of contractors are reluctant to touch them.

We are finding that the simplest form of external walls that dont require heavy labour and comply is actually Hebel.

I also have a really good fire shutter contractor that I would be happy to recommend to you. The key to keeping your costs down is to put a lot of thought into your window sizes during your design phase.

Our FZ builds with a pretty high specification are coming in around $2400/sqm as a guide.

There are a few reasons other than costs alone as to why we stay away from ICF the main one being that the concrete can take around 12 months to dry and you need to keep dehumidifiers running to prevent mould. The other reason is that contractors are limited in this area who have experience as opposed to good old core filled blockwork so you can negotiate a much better rate.

You can easily get the same thermal ratings without the added expense.

Also dont be fooled by the Gtech products, 15mm structural ply with tongue and groove is all that is required. Chances of your house burning down in Epping is pretty minimal. My lawyer is also a bushfire captain and he assures me that they will never let homes burn in the city. Remember the one at South Turramurra recently where they dropped the plane load of retardant on? there is a whole story about that.

Anyway, if you need any advice or some contractors just PM me and Id be happy to help in any way

cheers

Simeon

At $500/hr basic service ( if you can find it) you are going to wish you started with the right design, materials proofs/data, simulations, etc. Wishing you didn't waste too much money on Insignificant things like fake Realistic coloured renderings and spent more time analysing real materials costs/Mj/kg Vs Insurance premium increases.
OT, The problem why there's a shortage in Class 1 buildings is that they are too busy fixing up Architect designed apartments stuff ups after grenfell Here
Grenfell contractors ‘should have known cladding was combustible’

Thanks Chris and Simeon. I am a few weeks away from DA submission and thought that I consider materials before going into DA particular due to FZ. Think I will spend a bit more time on this topic to get the design right to minimise rework.

I got the windows sorted did some good research into that. The walls and roof needs more attention. Considering slab on ground for the house so not too much to worry on floor, maybe first floor.

P.S No flashy rendering ordered yet