Thread: what timber for external cladding and....

My two cents is that there is nothing wrong with using timber cladding in a fire zone....but there's very few timber cladding products that are not vulnerable to ember attack - either the product can catch and hold embers (eg. rough sawn, T&G) or the timber itself ignites quickly through radiant heat (eg. western red cedar, oiled timber).

Brick and concrete are the most effective barriers to ember attack and radiant heat. They do however tend to crumble once the house itself is on fire.....bushfires don't directly destroy brick & concrete - the house fire does.

Contrary to opinion, corrugated iron or similar steel cladding is actually quite crap in a bushfire. It is OK at embers (as long as the ends are properly sealed &flashed - which is quite rare) but not so great against close radiant heat sources which causes in-situ warping & buckling and can allow embers into the structure during the passage of the fire front.

According to the research literature, most houses are destroyed when embers fetch up in the roof space, in crooks against windows and doors and on timber decks.....and the great majority of them burn down in the period after the passage of the fire front....not during.

The reliance & debate about appropriate materials is wasted on its own. The most important thing with respect to houses surviving bushfires is design (of which materials is a part) and siting and then rigorous ongoing management.

All that said......on an extreme fire danger day like Black Saturday....if I lived in a house in a fire prone situation.....then you wouldn't see me for dust. The house would be as best prepared as I can make it but then it would be abandoned whilst we all go to the beach/river/someplace wet.

Yep understand all that and the point about corrugated iron is well made. There are a few houses around here clad with it and it would be interesting to see how they would fair versus my place which is clad with Hardi plank.

The thing is if you have a fire of that sort of ferocity, there's probably very little that will protect your house from it. It's more about the marginal cases I suppose. It is all about ember attack. I know that I might have a problem in my roof space, so if I have a fire, that's where I'll be concentrating. I know my cladding will never burn. I put some in a bonfire once. It was hot enough to melt a stubby but the cladding was barely singed the next day after several hours in the hottest part of the fire.

I just see it this way: you have a choice whether to build with timber or with something else. There are alternatives and they are probably cheaper (certainly by the time you pay for fire-retardant treatment). How important is it for your house to have that look? It's got to be worth considering, especially given that we're expecting bush fires to become even more frequent.

I think it's irresponsible to encourage people to use timber cladding in the bush without weighing up the alternatives. Not everyone can clear 200 metres around their house, and even if they can, that's no guarantee either because embers can carry a long distance. Further than 200 metres.

Keep the timber for the inside where you can enjoy it every day. The outside of your house is only for the neighbours

If you're hell bent on timber, I came across the list of 'fire retardant' timbers:

• Blackbutt
• Spotted gum
• Merbau
• Turpentine
• Red Ironbark
• Red River Gum
• Silver Top Ash

I put some merbau off cuts in my fire once and they do burn of course. It's slow to ignite but once it's going, it burns like any other wood does.

I agree it is more about the overall design of the house rather than the cladding.
If you clean gutters, have sprinklers on the roof,clean up bark under trees + dont have any gums really close to the house + window protection eg screens that would be more relevant.

Originally Posted by weisyboy

this is the reason i didnt put anything in the thread about the fires teh victus have noone to blame buit themselves and the greenies.

I've read some remarkable things on this forum written by you Carl and had trouble understanding a lot of them due to your obvious inability to use a spell checker but that statement is both ill informed and ludicrous. I reckon you should think before you type.

Originally Posted by SilentButDeadly

Welcome Michael

I really like this product as a cladding material....regrowth Euc and the like

http://www.radialtimbers.com.au/index.html

They even do it as flooring.

That does look interesting, Silent. Have never seen timber radially sawn like that before; I like the sloping sides.

http://www.radialtimbers.com.au/spec...mmB&B_Spec.pdf

When swmbo wanted a country place about ten years ago we looked at one in southern Tas that was clad in celery top pine with vertical boards and battens. Except that the battens were under, not ontop, of the boards. This made the 8 x 1.5 inch boards a real feature of the construction, and possibly slightly better insulation as there was a better airgap under the raised boards. Looked great.

Cheers

Graeme

In NSW new constructions have to be accessed by the local bushfire authority at DA stage for a few years now & given a level of fire protection risk which has to be met in the type of construction & materials, basically if your 100m plus from any bush your low risk & can build out of whatever you like, if your 20m away from a forest that can burn you cant use anything ignitable on the outside of the building.
regards inter

In my previous reply I made a mistake by advising you of the reference book by Keith Bootle not Richard Bootle as I mentioned.
I also mentioned Yellow Stringybark as a potential cladding more suited to cladding.After further research I am informed that Silver top is a timber used in fire retardent situations.
It is almost identical to the Yellow stringybark
Let me know how you get on

without entering the bushfire debate raging above I used shiplap boards in 19mm blackbutt on my extension and stained them to roughly match the cypress pine elsewhere on the house.
Definitely avoid the vertical orientation though if you want any chance of keep moisture out. Most timber guides will also tell you to scarf the end joints away from the prevailing wind/weather.
Also for the nails - galvanised helical 3.15mm x 65 titadecks
cheers
michael

Originally Posted by GraemeCook

That does look interesting, Silent. Have never seen timber radially sawn like that before; I like the sloping sides.

http://www.radialtimbers.com.au/spec...mmB&B_Spec.pdf
Cheers
Graeme

Been around for along time in the US & Europe, not used as much in Australia, but some examples in residential over 100 years old - better with softer woods. A very efficient use of the log with little waste - needs good timber though and care with stacking and drying too. See too http://www.radialtimber.com/start.htm and http://www.timber.org.au/NTEP/menu.asp?id=85

on the bushfire point, whether you build in hardi-plank, timber cladding, brick, mud brick, stone, fibro or any other type of material we need to consider how wind resistant our homes are.

Many homes in Vic simply had their roof ripped of by the wind! Doesn't matter how well prepared they were with sprinklers, pumps hoses etc nor the material the walls where built with. once you have no roof....your stuffed!

We have a chance at resisting certain bushfires with building solutions, but firestorms are over our heads!

We can resist nature to a certain degree but we will never be able to control it.

I have clad the rear of our new extension in a mix of the Radial sawn Silvertop ash you mention, in a shiplap profile, run vertically. No problems with rain coming in. There is a 12 mm overlap, and you put sisalation behind that obviously. The rest of the extension is clad in "Shadowclad" a rough hoop pine or radiata pine ply with grooves cut in it. This is LOSP treated, and stinks likekerosene or turps. THIS is what I am nervous about if a fire takes hold in or beside the house (we are not in a bushfire area.) I threw a couple of offcuts on a bonfire and boy, you should see them burn.

If I was in a bushfire area, I would be building an outside underground bunker, and forgetting about the house.

There were so many houses that were well designed that burnt, with people still in them, that a new approach needs to be taken. Build the house out of what you want, insure it well, but put your family's safety first and put in an underground bunker.

Hi Michael - I too am looking for some options in relation to external cladding so cannot really help you out in that regard. In relation to the concrete floor though I have recently put flooring over concrete and this is how it went. The flooring I used was a 12mm Tas Oak (which was a cheap option here in Tassie and I obtained the timber from a timber wholesaler at a good price - it was not perfect and had lots of sappy grain but this has really added to the effect- I suppose you could call it "seconds") I had to put a waterproofing substance on the concrete floor first (I cannot recall the name of it but it is a two pack substance and is good - used by the commercial people who lay timber flooring - quite expensive but good stuff), then used a commercial advesive to stick the boards to the concrete. obtain a straight line from wall to wall and work from there. I do have to say that it was one of the worst jobs I have ever done - very hard on the back and knees so get yourself some really good knee pads. I say the worst job but well worth it when finished. After I had done this a builder friend of mine said that another way to do it is to nail strips of timber to the floor, say 40x20 or thereabouts, reasonably close (bit like floor framing ) and then you can lay insulation between those (the thicker stuff - silver foil with white foam in the middle) and then lay the floor boards on top of this. This feels more like a timber floor to walk on and also takes away the cold of the concrete. Hope this makes sense and is understandable. Very best of luck!

made any decisions yet ,travlinbob or whatever.