Shed Base

Discussion in 'Builders' Talk' started by Rick1632, May 28, 2020.

  1. Rick1632

    Rick1632 Active Member


    I have a small garden that is completely paved and slopes gently away from the house - at one side I have 2 small sheds that each stand on half a dozen paves to raise them off the base. I'm thinking of decking the remainder of the garden and building a concrete base to put the 2 sheds on.

    I've been advised that it's probably best to deck on top of the existing paving stones, so currently my plan is as follows:

    1) Move the sheds and take up the paving stones where I plan to build the shed base
    2) Scrape off the sand that "levelled" the paves - underneath it's highly compacted hardcore.
    3) Make a timber frame, check level/square etc.
    4) Fill with concrete and smooth off with trowel

    1) Do I leave the frame in place afterwards, or remove it once the concrete has set?
    2) If the concrete is flat, water will collect on it won't it? How high above the concrete should the shed floors be raised? Currently I think it's only 1" thick timber pieces lifting the floor.
    3) Should the concrete be smooth, or brushed?
    4) The two sheds are similar in depth, so I'm thinking of making a single long narrow base for both of them, rather than two separate bases
    4) I understand the decking should slope slightly - which means if at the house end the base is level with the decking, at the other end it will be a couple of inches higher.

    Any thoughts, tips would be appreciated cheers!

  2. ramseyman

    ramseyman Screwfix Select

    No point in leaving the 'frame' it will only rot away in time

    Use pressure treated wood beneath the shed floor to keep the floor off the concrete base, at least 50mm thick, or better still rows of bricks or old concrete fence posts. Ideally I like the concrete slab to be just smaller than the shed so the majority of water running off or down drops onto the soil rather than back under the shed. If I was making the shed I'd extend the bottom board below the concrete to 'flash' it
    Rick1632 likes this.
  3. Rick1632

    Rick1632 Active Member

    Hmm - I'd need separate slabs for each shed for the drop down approach to work.

    If I'm going to raise the shed 50mm above the concrete then I should factor this in when I'm calculating the heights - i.e. set the concrete base about 40mm below the decking top so that the shed floor is just above it?

    Also - if I'm going to use timber under the sheds, then I guess I could slope the concrete the same as the slabs currently are and use the timber to "level" the sheds? (which is what I'm currently doing with the extra paving slabs under the sheds) That way any water falling on the concrete would drain away rather than pooling?
  4. ramseyman

    ramseyman Screwfix Select

    Yes and yes!
    Rick1632 likes this.

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