How can I find out/work out what bolts I need for my decking?

[DaKid]

Given that I have a large suspended decking (only about 600mm above ground), which will be constructed using 6x6 posts with 3x8 main joists (4.4m) supporting 2x8 cross joists (4.2m), and where the cross joists are resting on top of the main joists, how do I know what bolts to use to attach the 3x8 joists to the 6x6 posts?

One additional question, if it's simple. Would 2x12 main joists be better than 3x8? Both should be sufficient strength, but it seems 2x12 is that bit stronger.

 

[Notch7]

I would guess at M16, large 50mm x 4mm washers

Since they are long you might need to use studding.

Probably worth using stainless steel.

I buy from orbital fasteners.

 

[big-all]

are you aware you will need planning permission if above 300mm??

 

[DaKid]

are you aware you will need planning permission if above 300mm??

I've just been made aware of it, yeah. It seems a bit silly though.