Help with bullnose corrugated iron raised bed

Discussion in 'Fruit & Vegetable Growing' started by Comfort, Dec 30, 2016.

  1. Comfort

    Comfort Well-Known Member Premium Member

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    Hi... just purchased a range of colorbond sheets and there are a number of bullnose pieces... Each of these is just about 90 degrees so using four of them makes a nice rectangular shape with rounded corners.

    The problem is when you flip the pieces over the ridges do not match so I can't just overlap them and put a screw through both ... Has anybody come up with this problem before and how did you solve it.? I am thinking maybe some sort of joiner with a channel on either side for each of the sheets to fit into. Like you get for retaining walls to fit timber into.
     
  2. ClissAT

    ClissAT Valued Member Premium Member GOLD

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    Photos would be a big help.
    When you say ridges, do you mean the corrugations?
    Is there a different number of corrugations on the 2 sheets you want to join?
    Or has one sheet been flattened a bit?
    I'm assuming this is secondhand iron from a house?
    Or leftovers from a roof job & these are the rejected sheets?
    Having this info will help give you a satisfactory solution.

    The channel idea would work so long as the top of the joined sheets was level or could be levelled by digging one sheet into the ground a bit.

    But here's another thing to think about once you get your bed built.
    How wide are your sheets?
    If they are 720mm coverage you will end up with over a cubic meter of soil required depending on how long the long sides of your rectangular bed are.
    You can fill the bed with rubble or logs first then top with 30cm good soil.
     
  3. Comfort

    Comfort Well-Known Member Premium Member

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    Thanks for your response.... they are new sheets that somebody never got around to using so sold on Gumtree and still have the plastic on.

    These photos should explain the problem.... as you can see by the second photo when you flip over the sheet it does not align. The same goes for the 2 sheets that will make up the end. Every join will have two different profiles.

    I am thinking if i cant find something better then using 40mm flat aluminum on the inside. There will be small gaps that soil call fall out so I will have to deal with that.

    Ideally some sort of h profile aluminum extrusion that each sheet could slip into. I guess I could screw together 2 x U channels to get the job done.

    bullnose1.jpg bullnose2.jpg
     
  4. Comfort

    Comfort Well-Known Member Premium Member

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    I found this video... this is the sort of joiner that i am looking for... just for joining 2 straight pieces not at 60 degrees like is needed for this hexagonal garden bed.



    The other option I have is to only use two bullnose per garden bed in opposite corners which means that I can have all the corrugations all run the same way and joining the sheets is then easy.
     
  5. Comfort

    Comfort Well-Known Member Premium Member

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    I have quite a few different garden beds and have had to deal with this already.

    I have a couple of timber beds about 5 years old now, one short and one tall. The tall one has half of its height filled with bricks and rubble giving just 40cm of soil so I am familiar with the process.

    I have 4 x IBC wicking beds and a Hybrid RGGS as well.

    I want to have these garden beds setup as wicking beds as well... so I am thinking of the following vertical levels for the 800mm width of the sheets which will be the height of the garden bed.

    300mm of cracker dust
    200mm of water reservoir.
    340mm of garden soil

    The water reservoir will be created using builders plastic with voids created by agpipe or bread trays wrapped in Geofabric and then the reservoir filled with sand. This is the same way I have done with the IBC's except for the cracker dust layer because the ibc is only 500 mm high.

    I will make small reservoirs only 1.5m each long as the ground has a slight slope.

    This is the plan anyway.

    Plans are meant to change though!
     
  6. ClissAT

    ClissAT Valued Member Premium Member GOLD

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    Yes I see your dilemma. The sheets are all meant to be set over lapped over each other in a run.
    So the first corrugation is a little offset from the edge of the sheet.
    The sheets are 800 wide making a coverage of 720 or 740 depending on the depth of the corrugations, ie low or high profile.
    So you've got a set of right hand over lapping sheets rather than 2x right hand & 2x left hand over lapping. You could take a few cm off along the edge of the one that is higher. I know that is a lot of work but would cause the corros to fit. You would then have to pack up those 2 sheets under the bottom edge but that would not be visible.

    I think if you can get some of that H profile joiner as shown in the video you will fix your problem. A shed manufacturing factory should have it. You might find it is simply C section or Top Hat spot welded together along the flat side.

    The only problem will be putting something over the edge to cover it.
    On the one I have the guy sliced open some blue stripe poly pipe, then screwed it to the top as protection from the cut edge. I can get you a photo in the morning.
     
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