Laying a greenhouse base

My new garden is an old paddock which is now compacted clay which holds water when it rains and becomes solid in the sun,  I put in a rotary washing line in a concrete base and it has sunk, I'm worried that a greenhouse base will do the same,  Advise please,

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Posts

  • stuart.dotstuart.dot Bromley, KentPosts: 127

    I think it's common practice these days to sit sheds on concrete posts (laid lengthways of course). A lot less work 

  • Hi

    I am assumming that you are considering buying a greenhouse but concerned that a concrete base would sink in to the clay soil. Stuart's comments, with all due respect , are not really relevant. If you were to put a concrete base down for a greenhouse, you would use slabs. If you are concerned that the base would sink, then you would need to dig out the ground and lay a 100 to 150mm hardcore base ( broken slabs, bricks etc) The hardcore base would support slab etc tha

  • Continued 

    that you are intending to lay for your greenhouse. This should stop any collapse in the soil 

  • ShepsSheps Posts: 768

    I agree with, Steve...put down a good, deep layer of hardcore and use a mini wacker to compact it good and solid and you should be fine.

    This was my base ( pre Greenhouse ) laid on the same type of clay soil that you probably have.

    image

  • stuart.dotstuart.dot Bromley, KentPosts: 127
    greenfingers steve says:

    Hi

    I am assumming that you are considering buying a greenhouse but concerned that a concrete base would sink in to the clay soil. Stuart's comments, with all due respect , are not really relevant. If you were to put a concrete base down for a greenhouse, you would use slabs. If you are concerned that the base would sink, then you would need to dig out the ground and lay a 100 to 150mm hardcore base ( broken slabs, bricks etc) The hardcore base would support slab etc tha

    See original post

     Yebbut, it's a lot easier and cheaper to dig out a couple of 4" channels. It's a shed, not a drive image

  • Thank you both for your very welcome advice, I feel more confident now.  I'll probably play on the safe side and do the digging and hardcore, wish me luck.  Happy gardening  Last question,  can I use broken up roof tiles in the hardcore?

    Last edited: 19 February 2018 08:59:20

  • Stuart 

    Actually, it's a greenhouse. So I am assuming that your suggesting to bed these concrete posts in to the ground and then lay a slab base. Without laying a consolidated hardcore base then there could still    a chance of subsidence based on the problem that they are having with the clay structure. In any slab construction you need a consolidated ground. Fortunately, the weight of the greenhouse is not that extreme so your suggestion could work but personally I would not take that chance 

  • Hostafan1Hostafan1 Posts: 16,817

    " if you fail to prepare, you should prepare to fail" 

    A shed might go a bit wonky if it moves, a greenhouse will lose its glass. 

    I think , for the sake of a bit of hard work, I'd go with a proper base. 

    Your garden, your greenhouse, your money, your choice.

    Devon.
  • Thank you, it's difficult to know exactly what sort of base to lay as concrete doesn't help with drainage, which is a problem over the whole garden.  

  • stuart.dotstuart.dot Bromley, KentPosts: 127

    Actually, yes, it's a greenhouse and not a shed, so the concrete post idea is not a good one. Should have read the question before replying!

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