Decking dilema

Discussion in 'Landscaping and Outdoors' started by Danrover82, May 19, 2020.

  1. Danrover82

    Danrover82 Member

    Hi all,

    I have a decking to do 7m wide by 2.5 deep, and the land is really uneven,

    From the highest point in the garden where its going it runs out +120 at long the 7m and 10mm front to back on high side and 90 on the 120+ end on the lower side.

    My original plan was to sit on 30+ breeze blocks on the ground and either as its a low level and I didn't fancy digging loads of holes given I've recently done my fence and dug s*** loads for that.

    My joists will be every 450 and are 5x 2 with Deck boards 150 wide ☓ 38

    I've seen the adjustable deck bases but I thought they were expensive for the amount I need.

    Ideas and thoughts please?
  2. Severntrent

    Severntrent Screwfix Select

    Get a piece of plastic drainage pipe 100 or 150 and cut to desired lengths to bring up support to requsite height, get initial height of breeze block to within 50mm of final level
    chillimonster likes this.
  3. Danrover82

    Danrover82 Member

    Wouldn't the drain pipe sink in ground overtime?
  4. jactac

    jactac Member

    Just replaced my decking after it being down over 20 years, same issue steep gradient.
    I used a combination of breeze blocks with 4 inch treated timbers on top of the breeze blocks, making sure the breeze blocks are on solid level ground.

    Used the same process when I first put the decking down over years ago, no issues whatsoever.

    Like you I would of though that soil pipe would cut into the ground ?
    Unless we are both thinking the wrong thing ?
  5. Danrover82

    Danrover82 Member

    Yeah. I see the benefits of the pipe though, but wouldnt trust blocks on top.

    With the ground so bumpy the blocks don't sit brilliantly flat, so maybe worth chopping in half?
  6. Severntrent

    Severntrent Screwfix Select

    To be placed on top of a breeze block, unless you can get blocks all on same level
  7. Danrover82

    Danrover82 Member

    What about digging into joists?

  8. jactac

    jactac Member

    Still a bit confused ?
    If you used pipes as "legs", sitting on top of breeze blocks, how would these pipes (legs) be fixed to the joists ?
    Surely you wouldn't just balance the pipes on breeze blocks with the joists sitting on top of the pipes !!!
    Maybe I'm just not getting it ?

    I used full blocks and half blocks depending on what was needed, the 4x4 posts then sat on top of the blocks and the joists were then fixed to the posts, simple, strong, sturdy and level.
    I also protected any cut ends in the 4 x4 legs and joists with a timber decking sealer for cut ends, and used a decking oil for the deck boards.
  9. Danrover82

    Danrover82 Member

    Sound, I have 3 mtr left of 4x4 post from my fencing so that could work and I think I'd have enough.

    Local council wanted me to dig them in ground (H+S) but can't see it moving or lifting
  10. Severntrent

    Severntrent Screwfix Select

    Hopefully you are using C16 or C24 timber and not balsa wood
  11. Severntrent

    Severntrent Screwfix Select

    Its a 7 x 2.5 lump of timber, the pipes are no more than spacer pieces resting on top of solid breeze blocks so there will be no lateral instability due the pipes flexing in the vertical direction unless you run into it with a JCB from the side
  12. Danrover82

    Danrover82 Member

    Yeah all graded timber.

    Where's cheapest place for sealer?
  13. Danrover82

    Danrover82 Member


    Managed to get all frame and boards on. But not totally happy. So may need some advice now.

    I decided to put a slight fall on the deck from center to either side to allow drainage, but I can see the hump.

    The righthand side where the patio is the deeper side where I have blocks and legs and is Solid, really happy

    Left hand side started with joists on floor and gradually packed up with legs on Blocks etc. Although for some reason there appears to be some give/bounce in the deck and it's left me pretty deflated.

    Any ideas or just paranoid or over reacting?


  14. jactac

    jactac Member

    What size are the joists and joist centers ?
    What thickness are your deck boards ?

    I used 6 x 2 joists with 16 inch centers, totally solid.
    My deck is 38' x 11.0' , it spans 2 levels where the garden slopes downwards.
    I ran 3.6 mtr boards diagonally (no need for cuts).
    The deck boards are finished at 32mm thickness, which makes hell of a difference compared to 28mm boards.
  15. Danrover82

    Danrover82 Member

    Joists 5x2 at 450 centers
    Deck boards 32mm

    Took two borads up and added additional support. Seems a lot more stable now
  16. wiggy

    wiggy Screwfix Select

    By running your boards at the angle (45) you have increased your span to about 565mm (22inch)

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