shed foundation

Discussion in 'Builders' Talk' started by urbantus, Apr 27, 2007.

  1. urbantus

    urbantus Member

    Im building a large shed in garden
    4800 x 3600 mm base

    the top soil is quite loose
    clay about 300 mm down

    Im going to build a timber basr using joists and floor boards

    whats best support for joists

    a slab with mesh erected on top of the soil

    or two or three ground beams running 4800 mm ie along front middle and rear of shed base
    plus concrete blocks to raise it above ground

    how many bags of cement plus chippings wouls i need per cubic meter of concrete

    i have to mix by hand as access is bad


  2. STGO

    STGO New Member

    Tell the truth about your "shed" mate, we are all friends here. No-one will grass you up if all sounds ok.

  3. urbantus

    urbantus Member

    Sorted out how much concrete etc

    But need some help
    The shed is goint to bequite heavy

    The ground is shrikable clay

    Will two strip foundations 3.6 m apart be ok to support the shed

    Im going to make them 4.8 m long
    0.45 m wide
    What depth do you think I should make them

    As the timbers are spanning 3.6 m should I use 9x3s for the floor


  4. sorry old chap but your idea sucks...

    you need to cast a full sized slab...6" thick, embedded with rebar
  5. urbantus

    urbantus Member

    Im gonna go with the slab idea

    The ground at the mo is very dry and digs up like dust
    Im gonna dig down to harder ground and put in some scalpings then 150 mm concrete with mesh reinforcing in it

    i might still lay some concrete blocks on top of slab to raise joists up a bit

    am i heading in the right direction

  6. limestone cowboy

    limestone cowboy New Member

    If you're putting a slab in, why bother with the joists and timber floor? Just use the slab as the floor.
  7. bigjules

    bigjules New Member

    If you're putting a slab in, why bother with the
    joists and timber floor? Just use the slab as the

  8. STGO

    STGO New Member

    But its gonna be a "shed" so the floor will need insulating ;)
  9. urbantus

    urbantus Member

    Im going to make it really cosy for sleep overs etc

    going to insulate the floor roof and walls

    thats why I want joists and timber floor

    urbeh the shed dweller
  10. urbantus

    urbantus Member

    I have a problem casting the slab

    The top soil is 550 mm deep before clay
    Theres a really big laylandii tree a meter away from the new slab area

    Do I need to take the tree down

    Do I need to dig down into the clay

    If so how deep

  11. Willy Duwitt

    Willy Duwitt New Member

    We're talkin about a freaking shed here chaps!!

    Excavate 300mm, put down and compact 150mm hardcore, blind it with sand, then yer 150 mm concrete.

    We did my mate's shed/workshop about 6 years ago ( 6.5m x 4m ). We dug out about 250mm, put down 150mm Type 1 MOT, then 50mm grit sand/cement and covered with some old 50mm 3x2's and 2x2's and the shed sits on some old railway sleepers. In that time not a single flag has moved.

    Basically, what I'm saying is to use common sense. There's no point over-engineering the project.

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