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hyjoist for subfloor

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  1. #1
    Apprentice (new member)
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    Default hyjoist Vs traditional subfloor

    Hi All and apologies for this possibly stupid question ... We recently rented a shop where the subfloor had been removed to provide storeage, and replaced with Hyjoist spanning 3.8metres. So this got me thinking, is this was an option for my home renno?

    I am planning (no I've not started yet, so you can all sigh with relief ) the subfloor of a 4.0mx10.5m ground level extension to the back of our house. Been on the CHH site etc and downloaded the design software (technical for the DIY amateur ).

    Here's my confusion. Does the use of "Hyjoist" reduce the number of stumps required (currently 28 set at intervals 1.5 x1.5 approx.) or is the product merely a replacement for traditional joist timbers?
    As I am using sheet flooring, do I have the option of 2 bearers (one at each edge) running the 10m length of the space with hyjoist spanning the 4m space at 440mm intervals?
    Structurally am I still required to place bearers every 1.5m and stumps beneath them at every say 1.2m if using hyjoist?

    In this costing stage of course my interest is to reduce materials costs AND the amount of hole digging. Labour is self inflicted so no further savings there. I should add I am in Victoria so the usual concrete or hardwood stumps are to be used. (too much slope for concrete slab).

    Thanks for your interest, what do you think?
    Last edited by gordon1; 27th Sep 2009 at 04:42 PM. Reason: Heading wrong

  2. #2
    4K Club Member ringtail's Avatar
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    Default

    G'day mate. Yes the hyjoist is designed reduce the number of bearers. 4.0 span is nothing and would easily be done with them. Get your arch or drafty to size them for your project. We clear spanned 6.0 for the upper floor on one house, no drama.

  3. #3
    Member rileyp's Avatar
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    Default

    Im in Vic as well.
    I used hyjoists on my extension 10 years ago.
    We have pine floor boards .
    There is no more flex in the hyjoist floor than the original post and beam/joist floor
    I have 4 strip footings each at a span of 4 metres.
    Pryda also make a similar product (prydabeams)
    Note all woodwork should be at least 300mm from the dirt to stop the ingress of moisture.
    cheers rileyp

  4. #4
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    Many thanks for the support (no pun intended). Especially to find a user from Victoria. Most posts I have read are Qld & NSW and it concerned me that Vic might have quaint building regs (again!). From what I have read, it seems insane NOT to use Hyjoist or similar. I did have concerns about the ground floor use so appreciate the 300mm/moisture info, particularly as I am in a mountain district.
    Does anyone know of suppliers in the Melbourne metro area, particularly east/outer east region? And any actual price guidelines. The sale sites I found via CHH were limited in Vic and other prices ranged from $10+ to $16+ per L/m.

    and Rileyp....did you sit the joists on support timber, or "hang" from?

    Thanks again

  5. #5
    Member rileyp's Avatar
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    My hyjoist are nailed to a 90x45/damp proof course/continuous brick wall 2 bricks high above the strip footing. On external walls its double brick for 2 courses lol
    10 years ago they started at ~$10 plm for the hj200's and they are still about the same
    My chippy went 1 size bigger than the chart suggested to make the floor stiffer
    I have 4m spans and hj240's were used
    They would prob $12 plm
    You can get pricing through this web site but you must input your state as NSW.
    Timber pricing doesn't work if you input vic as your state!
    http://buybuildingsupplies.com.au/
    Edit ($10.47!)

    Hybeams are made at Nangwarry SA (I think) just over the border so pricing will be the same if not less than NSW.
    edit 2.... hybeams must always be supported from the bottom whether you use a bracket like a pergola bracket or just sit in on something makes no difference as long as its supported from the bottom.

    I chose hybeams rather than conventional flooring as stumps in clay are a bad mix and saw the strip footing as the most solid altenative.
    I must admit though the original house which is now 40 years old is in very good condition with only the usual cracks above some of the doorways in in the plaster .
    The exension however in the last 10 years has no cracks in the plaster whatsoever.
    The pine floor boards on the hyjoists have gapped a little unlike the original pine floor on the hardwood joists bearerrs which is tight everywhere.
    I think this has something to do with my floor being put down in a wet may rather than in the summer when the boards are dryer and thinner.
    cheers rileyp

  6. #6
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    Thanks mate, you're a DIY's treasure. having drawings put up now. I'll post pics as the work progresses incase there is another idiot like me out there who needs this info in the future.


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