How to build low-floating deck using pedestal feet?

[simont]

Hi everyone,

I’m planning to build a low, free-standing deck and would appreciate some advice before I start.

Deck details:

• Dimensions: 7000mm (L) × 1530mm (W)
• Height: approx. 230mm from ground to finished deck surface
• Decking: Ekodeck 140mm × 23mm
• Free-standing: I prefer not to attach anything to the brick veneer

Proposed structure:

• Using plastic pedestal supports instead of posts/stirrups in the ground (to avoid digging and concreting).
• Two rows of double 90mm bearers, running the 7m length: one near the house, one near the front edge.
• 90×45 joists sitting on top of the bearers (not flush), spanning the 1530mm width.
• Approx. 250mm overhang past the front bearer to hide pedestals behind the fascia board.
• I chose bearers because it seems easier to level two rows of bearers rather than levelling 15–17 separate joists on pedestals.
• I prefer joists on top of bearers so I don’t need to use joist hangers.

Questions:

1. The Builders Edge Pedestal Feet products (eg. Smallfoot) seem marketed to support joists only.

• Can they support double 90mm bearers (ie. 2/90x45) instead?
• If not, would TuffBlock work better?
• If using TuffBlock, is the correct method to insert a short 90×90 post section into the block and cut to height?

2. When looking at bearer span tables, most rated sizes appear to be double bearers.

• Does a deck like mine require double bearers?
• Or can I use single bearers on pedestals?

3. Because this will be a floating deck on pedestal feet, do I need to consider lateral movement?

• How do I ensure the deck doesn’t shift over time without fastening to the house or concreting posts?

4. Will this configuration meet minimum ground clearance requirements for composite decking?

5. Any concerns or better suggestions for the structure described above?

6. For Ekodeck fixing, should I use the 3mm or 6mm Quickfix clips for this layout?

Plan and reference photo attached.
Any advice would be greatly appreciated, thank you!

 

  

[simont]

Thanks @MitchellMc .

I do use the Edge Board for the board furthest from the house wall.

What I meant by the 'last board' is the board closest to the house wall. This is the board I need to rip to size, and unless I’m mistaken, the only way to fix it is by top-fixing. Is that correct, or is there a better method that avoids top-fixing altogether?

While we’re on the topic, I understand the fascia board will also need to be face-fixed. Is there any way to install it without visible face fixings?

I’ve attached some photos, hopefully they provide the necessary context. (Please ignore the fascia installed in the photos, those are just temporary off-cuts and will be removed.)

 

 

Thanks. 

[JacobZ]

Hi @simont,

Face fixing that last edge board is the simplest and easiest way to do it and with a bit of paint, the screws wouldn't be too noticable.

In saying this, you could refashion the groove, which would allow you to use a C-clip, but this would require a router, a specialised bit and some careful planning to ensure it lines up correctly. I wouldn't call it a beginner skill, but it is possible.

Unfortunately, with the fascia board, there is no way that I'm aware of to avoid a face fixing on one edge of the board because of the way the C-clips are screwed in place. If you are using an edge board, I would but the C-clip in the groove on the back of the board and then screw in the bottom edge. Having one row of screws low down to the ground won't be too noticable.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob