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Decking bearers, Hardwood V Treated Pine V steel purlins

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  1. #1
    Apprentice (new member)
    Join Date
    Nov 2009

    Question Decking bearers, Hardwood V Treated Pine V steel purlins

    G'Day Mates,
    What is more long term cost effective for bearers, Local Hardwood, Treated Pine, Steel Perlins?
    I need to replace an existing deck or maybe just some of it.
    The area is 7.5m long by 2.5 wide. The span between posts is also 2.5M
    The deck is off my 2nd floor so is about 3m above ground.
    The original bearers were Oregan, as specified by a supplier, everyone tells me that was my first mistake.
    The balcony is on the Eastern side of my house & shaded form the North & East by trees so although I am on a ridge it does develop a fine coating of grey mould, maybe scrubbing it more often be the go there.
    Whats the go with Treated pine decking, is the corigated side supposed to be the top or bottom surface?

  2. #2


    Oregon should have been OK but you need to protect it, IE paint it... I have some Oregon in a pergola thats 25 years old and has been painted with quality paint twice and the wood is still as it was when built. But in saying that, you have a large deck there and high up... I think you need a pro to design that for you.. Patching and your insurance could be iffy, There is too much risk there. Get professional advice. .. Ribs go down by the way.

  3. #3
    1K Club Member Pulse's Avatar
    Join Date
    Jan 2005
    Port Macquarie


    treated pine will be the cheapest. the others may last longer but if you use some flashing between the decking and joists it should last for ages (50yrs +)

    Oregon was popular but as an untreated softwood outside it won't last. Our pergola lasted less than 10 years, the stumps were around a spa and rotted.


  4. #4
    Lumberlubber Bleedin Thumb's Avatar
    Join Date
    Aug 2006


    I think you will get the same life out of CCA treated bearers and joists as durability Class 1 HW. More if its constantly moist.

    I prefer CCA as its lighter and easier to install and to nail/screw into. I prefer HW as my decking boards
    because you can't get CCA decking and I don't like or trust LOSP's longevity. ACQ maybe at a pinch.
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  5. #5
    Rigid Member UteMad's Avatar
    Join Date
    Mar 2007


    Mate take the treated pine and whack a coat of stain or oil over it if you want a longer life .. Oregon is now classed internal use .. Our record is 4 years on an oregon balcony.. the owner noticed it deteriorating at 2 years and dept of fair trading paid us to replace it at 4 years after the builder went bust.. paint doesn't protect oregon externally as once it finds somewhere to penetrate it sucks inside the coating and cant dry out without coming back to where it was absorbed .Plus most people do a sensational paint job after the build and leave the end grain to suck up water like a sponge.. from what we've seen oregan structures painted dont last as long as ones that were pre stained before ercetion as the oil stain repels the water

    cheers utemad

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