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30th January 2014, 11:06 PM #1Novice
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- Jun 2012
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- Gold Coast, Queensland
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wood experts please help! which timber is stronger..
Hello guys,
later this year i will be planning a 6x3m raised shed build ( off the ground 1/2 a metre to 1m)
the plan is to have 4 150x150 Glued laminated posts.
having trouble with bearer and joist options:
either,
Glued laminated white cypress durability class 1, F11
or, Glued laminated treated slash pine F22
bearer size: 300x65 joist size: 260x65
which timber type would be the strongest in the application?
thank you for any replies.
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31st January 2014, 10:19 AM #2GOLD MEMBER
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- Aug 2004
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- Perth WA
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- 1,621
Why are you even bothering with timber of any description? Use steel.
Experienced in removing the tree from the furniture
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31st January 2014, 08:25 PM #3Novice
- Join Date
- Jun 2012
- Location
- Gold Coast, Queensland
- Posts
- 12
i dont have the equipment to cut and work with steel beams.
timber would be far more easier for me.
cheers.
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31st January 2014, 10:09 PM #4
F22 is the higher stress grade, if that's what you mean by stronger.
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2nd February 2014, 11:01 AM #5Senior Member
- Join Date
- Nov 2011
- Location
- pomona
- Posts
- 100
OVERKILL
Breakerboy, the sizes you are considering are way to large. A 200 x 75 hardwood bearer will easily span 3m,(use 3 of them in 6m direction with three posts supporting each). Your joists can then be 100 x 50 hardwood spanning 1.5m either side of middle bearer. Unless you are doing it for appearance, 100 x 100 posts are amply strong. Cheers, Timboz
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2nd February 2014, 08:47 PM #6Novice
- Join Date
- Jun 2012
- Location
- Gold Coast, Queensland
- Posts
- 12
Thank you for the responses.
Timboz, I know my beam sizes are overkill, yes they would be partially for looks but also,
Would a design work with only 4 posts supporting 2 bearers running the 6m length with my joists on top of them running the 3m length @ 450 centres
If I used the dimensions I said previously, would it be enough support without adding 5 extra posts?
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2nd February 2014, 11:21 PM #7Senior Member
- Join Date
- Nov 2011
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- pomona
- Posts
- 100
SHED DESIGN
Breakerboy, engineering wise, what you would achieve with only 2 bearers would be what is known as 'single span' joists (ie only supported at two points). This configuration results in much greater deflection of the joists than the same sized joist but double the length spanning the same distance but supported at both ends and in the middle (which is known as 'continuous span'). Imagine your joists were each 6m long (as a single piece of timber) and supported at both ends and the middle. Each 3m span would deflect less than your single 3m joists with a bearer at each end. As well as this, a bearer spanning 6m would probably need to be 500 deep! You could rotate everything 90 degrees and have 3 bearers running in the 3m direction (250 x 75 single span) with 6m long continuous span joists (150 x 50) @ 450 centres - so 6 posts. I still think 9 posts as per my original suggestion would be cheapest/strongest. If you want to play around with ideas search "Thora Timbers"
and download a span table. You'll have to research what load widths are and be careful to note whether an element is continuous span or single span. Also note that most Aussie hardwood timber sold as F14 will in fact be F17 or higher and will season to become even higher. Good luck with it Timboz
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2nd February 2014, 11:28 PM #8Senior Member
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- Nov 2011
- Location
- pomona
- Posts
- 100
Extra info
Breakerboy, You could have your 6m pine bearers but supported by 3 posts and use your quoted joists but do price out my suggestion also. Timboz
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3rd February 2014, 02:54 PM #9SENIOR MEMBER
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- Dec 2010
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- Melbourne
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If you download the span tables(off the forum,sorry I can't remember the post)you will have all the detail you need to decide the best outcome.
They are there for softwoods and other with all the gradings.
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5th February 2014, 09:26 AM #10Novice
- Join Date
- Jun 2012
- Location
- Gold Coast, Queensland
- Posts
- 12
Thanks mate, after thinking about it I will probably be better off with 6 or 9 posts as you suggest. It will be for a woodwork shop so there will be some equipment, a couple heavy timber work benches etc and I would want as solid sturdy shed
as possible. I have looked at span tables but haven't found much for the glulam type
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