Raised Garden Workshop self build help please

Discussion in 'Carpenters' Talk' started by SparkyAnt, Apr 19, 2021.

  1. SparkyAnt

    SparkyAnt Member

    Hi there,
    My first post, hopefully in the correct section...
    This might be a bit long winded and few basic questions so please bare with me :)

    I’m looking to build a workshop in my garden, 4.8m x 3.6m ..exact (4880x3660) good n strong

    The garden is on a slope apx 15-20 degrees so think my best option after days on YouTube to save digging out a good few tons of muck is to make it raised and fixed on 4x4 posts concreted into the ground with bearers/skids on top and build the floor off that.

    idea is..
    Hand/petrol auger ,go 500ish deep each hole.
    Layer of compacted/tamped MOT in the base of the hole and proper concrete not postcrete with 4x4 upright posts
    Once levelled, I’ll cut the upright posts down to size and then fit galv steel u shape brackets on top. I’ll then fix the bearers/skids to them.

    The plan is to Support the base every 600mm
    4.8m div 8 = 600
    So 24 holes -3 rows (front/mid/rear)
    The 3 rows will be equal spaced 1200ish
    Is this overkill or not?lol
    Hope that makes sense how I’m trying to explain it

    Does my plan sound good or naff or completely overkill!!!
    Be really grateful for some ideas and opinions :)

    Also another question
    I’m looking to use 5x2 or 6x2 for the base, given the spans I have what would be best, noggins spaced ev 16”/405
    And... what size screws would be ideal for fixing all together?
    Thinking 6x150mm for the main joists and 6x100mm for the noggins??

    are there ‘specific’ joist screws to use that a designed for the weight and use outdoors?

    Thanks for any and all help guys I really appreciate it

    . . . . .
  2. SparkyAnt

    SparkyAnt Member

    I got my maths wrong!
    The 3 spans / rows would be..
    Front - 0
    Mid - 1800
    Rear - 3600

    Not 1200 each as in 1st post
  3. stevie22

    stevie22 Screwfix Select

    If it were mine I think I would skip the wood posts and use cardboard (or plastic) tubes to extend my pads up into columns. Go down to good solid ground rather than set a depth and undercut the hole bottom to increase the bearing area. 3 rows of 3 pads and timbers sized to suit.

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