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Preparing for a new greenhouse

Hi all just wanted to get your views on teh ground preparation for a new greenhouse. I have soem paving slabs already but want to get some guidance on whether I need hardcore and sand before laying , and if so at what depth? The green house I am likely to buy will be fairly large, probably 10ft x 6ft. Thanks in advance for your help!


  • If the paving slabs have been laid properly erecting on a greenhouse on them will be fine.
  • KiliKili Posts: 1,022
    I have a 12' x 10 or maybe a 13' by 9 cant remember. All I did was use some old wood to make a 4 inch deep shuttering about 4 inches wide and put some concrete in there for a base. Screwed the greenhouse to my 4" base then laid slabs inside on a bed of sand. any excess water just runs through the cracks of the slabs into the sand.

    'The power of accurate observation .... is commonly called cynicism by those that have not got it.

    George Bernard Shaw'

  • nick615nick615 Posts: 1,292
    Little Jan Obviously I don't know your capabilities, but most 'bought' greenhouses leave a lot to be desired in terms of design.  Of course they work, but they could also be improved so, if you can, a couple of hours with pen and paper might enable you to design and construct your own?
  • Oh wow that’s an out there suggestion ! Not sure I can do that   I was being adventurous forming the base myself ! Love the idea though , thank you 
  • PlantmindedPlantminded Posts: 1,976
    Hi Little Jan, this thread from the forum in 2018 should help you:

    Slab Base for a new greenhouse — BBC Gardeners' World Magazine (

    I've tried levelling flags myself - it takes practice! (I called in a professional after my unsuccessful attempt!)

    Good luck and enjoy your greenhouse!

    Wirral. Sandy, free draining soil.
  • Thanks very much ! Really helpful 
  • Pete.8Pete.8 Posts: 9,983
    When I was deciding on which greenhouse to buy I found that each manufacturer had an article on their website giving instructions on how to prepare a base for it.
    I bought a Rhino that I'm thrilled with and about 1/2 way down this page are the instructions and options available for base installation.

    For a Halls greenhouse-

    Best of luck with it and hope it gives you many years of productive pleasure :)
    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • so helpful thank you. I was looking at a halls actually as a rhino was that more expensive!!! Exciting 
  • BobTheGardenerBobTheGardener Posts: 11,391
    edited December 2021
    It's worth checking the total price with any vents, automatic openers etc. included, as some makes like Rhino include those in the price, but with many brands they are extra.   The Rhino bases are built-in and extremely strong - enough so, that the GH can be laid directly on compacted ground (not recommended, of course) so require less substantial foundations, if the location or other factors makes digging a 'proper' foundation difficult.  It's essential that any make GH is laid on level ground though, so be sure to get that right. :)

    A trowel in the hand is worth a thousand lost under a bush.
  • Thank you @BobTheGardener, I will have another look at rhino now. It’s a big investment so it does need to be right 
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