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  1. #1
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    Roof Posts Span Question.

    I am going to extend the roof of an existing building. I want to use 2 inch steel pipe as posts and I was wondering what length of span between posts. The shade roof will be tucked in under the existing roof. I will use the corrugated panels which are common around the country. One side of the building will have a 2 meter overhang extension, while another side will have a shade extension of 4 meters. I will be using the C type of metal on top of the posts, and also to latch the roof panels onto.

  2. #2
    lob
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    i'll take a chance

    was/am inclined to let someone else reply first as not sure of the question. if i'm getting it right, why two inch posts?. 4mtr spans ok with the correct weight c type steel. two mtr over hang? dont expect to put your weight on it. four meter overhang?, dont be under it when its erected. forget playing foreman, let the boys do it, they normaly know what they're doing, contrily to some opinions. if i've got it rong, missunderstood, my apoligies.

  3. #3
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    2inch for your pillar supports is strong enough in compressive strength in theory, trouble is if it gets knocked out of true just a bit then it will have lost its integrity, ie clip it with a car, hit it a bit hard with a motorbike, 150 kilo friend leans on it and the whole lot becomes structurally unsound.

    4 meter would be your max span using 3inch "C" steel as cross beams.

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    ohhh, and you wouldn't be able to do a 4 meter by 4 meter roof using 2inch supports, ie one in each corner, that aint gonna hold, the 2 meter one you might get away with it although most countries probably wouldn't allow it.

  5. #5
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    But you have to figure that here you will not need a 40 pound to the sq.ft snow load either.

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    Rain can hit pretty hard, be interesting to find out how much whack a real good storm can give a roof, this room the balcony door is 2 meters high, the rain has hit the wall at a height of 30cms, the wall is 8meters away from the door, thats pretty strong rain and winds.

  7. #7
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    Quote Originally Posted by dirtydog View Post
    2inch for your pillar supports is strong enough in compressive strength in theory, trouble is if it gets knocked out of true just a bit then it will have lost its integrity, ie clip it with a car, hit it a bit hard with a motorbike, 150 kilo friend leans on it and the whole lot becomes structurally unsound.

    4 meter would be your max span using 3inch "C" steel as cross beams.
    For the 2 meter wide overhang, I was planning to go 3 meter spans with 3inch "C" steel as cross beams, and 2 inch "C" steel for the panels to latch onto. The posts will have 6mm thick steel base plates welded on, which are drilled for 3/8 inch bolts, that will be sunk into existing cement floor, and cemented over.
    I guess for the 4meter overhang using that square metal which is about 4 inch as corner posts would work out better. Could I use the 2 inch for spanning in between? the area here is about 10 meters long, or do I need to go the length with the larger metal, and if so what kind of span would be appropriate?
    IF I didn't play foreman lob, I would soon be up shits creek, and this place would be a total mess.

  8. #8
    Days Work Done! Norton's Avatar
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    Quote Originally Posted by mellow
    The shade roof will be tucked in under the existing roof.
    I'm contemplating similar as a car port. Will stayed tuned for ideas.

  9. #9
    disturbance in the Turnip baldrick's Avatar
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    can we ask splitlid to whip up some diagrams ?

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    Thailand Expat Texpat's Avatar
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    Earlier this month I installed a 12 sqm awning adjacent to my carport. (4m x 2.5m plus sides)

    I used to have a nasty plastic supported shade that was in desperate need of replacement.

    Been trying to upload pics but no can do. Will post later. Two inch steel pipes ~4 meters apart. post pics later.

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    It sounds horrible, why not design something better looking

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    What do you mean buy overhang? Is this the distance from the existing building to the posts? or how far the roof will counter leaver from the posts?

    Have a look here http://www.timberqueensland.com.au/a...20carports.pdf for some termanology on members.

    The biggest problen in roofing is not in compression strenght, but in uplift and suction! As wind passes over you roof in sucks the the roof up and as it passes under it, it creatate uplift on your eveas (soffit) or for an pergola the under side of your roof!

    Your magor concern, should be holding down your colums and diagnol bracing.

    f you can relate the terms you use too my link I can help you!
    Lift your feet!

  13. #13
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    Quote Originally Posted by baldrick View Post
    can we ask splitlid to whip up some diagrams ?

    no, i think this is a job for hillbillys sticks and dirt method.

  14. #14
    lob
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    why not go concrete posts way. put in what u need. max 4mtr spans 1/1.5 mtr overhang. 3inch/75mm c girders too small for 4mtr span 4inch/100mm = 4mtr span . there is a colour coding for steel weight. ie white yellow blue and maybe red, not sure about the red. heavier gage = stronger stress. 2inch/50mm is right for 1mtr centres for your roof sheets. as i said the boys will know all about this. although you cant get them to do anything new, they know what they know and have been doing it since they left school, in some cases before. relax go with the flow.

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    Thailand Expat Texpat's Avatar
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    The reason I put this in was direct sun on my truck all afternoon and when it rains hard the rain soaks everything in the carport. Not sure how long the aluminum top will remain rust free, but will paint with rustoleum at first sign. It's 4m x 2.5m

  16. #16
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    texpat you'd better edit your post before someone comes on here calling you a "dumb yank"

  17. #17
    Thailand Expat Texpat's Avatar
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    Nope. Read it twice. Not the best piece of writing I've ever made, but nothing wrong with it.

    I don't think this forum allows namecalling. People have been sent to jail for it.

  18. #18
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    yeah, but only if its not true

  19. #19
    Days Work Done! Norton's Avatar
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    Quote Originally Posted by Texpat
    Not sure how long the aluminum top will remain rust free
    About two years. I'm redoing some of the same on my place now.

  20. #20
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    Quote Originally Posted by Texpat
    the aluminum top will remain rust free
    Quote Originally Posted by splitlid
    texpat you'd better edit your post before someone comes on here calling you a "dumb yank
    Quote Originally Posted by Texpat
    Nope. Read it twice. Not the best piece of writing I've ever made, but nothing wrong with it.
    I suppose the thing is that aluminium does not rust, ever

    not ever, not at all

  21. #21
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    Quote Originally Posted by Norton View Post
    Quote Originally Posted by Texpat
    Not sure how long the aluminum top will remain rust free
    About two years. I'm redoing some of the same on my place now.
    yep not even after two years

  22. #22
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    Actually, aluminium does rust (kind of), but not in the same way as ferrous metals.

  23. #23
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    ^
    putty

  24. #24
    Thailand Expat Texpat's Avatar
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    Fair point. Not sure what metal it is. It feels like aluminum so I assumed it was made from recycled beer cans or something similar.

    Whatever it is, it's sure to start falling apart after a year or two and will require attention. I've found that rustoleum to be some pretty good shit for stopping rust.

    Metal, plastic, wood -- Thailand just isn't a nice place for building materials.

  25. #25
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    Larger metal beams can get to be expansive. I have seen some places where they used a pipe, say 2 inches, then encasing it in concrete pipe, and pouring cement into it. Welding a little barb wire around the metal pipe would probably increase the adherence of the cement, to the pipe I would think. This would be an economical way to increase the compression capability of the post. Cement posts are fine, but don't work so well on existing slab. Any suggestions on above technique?

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