decking framework

[gingerneil]

I have spent two days reading decking questions here and elsewhere, and advice seems to vary loads!
I'm building a 3x5.6m deck, planning on using 50x150 for the framework. Spanning tables suggest I can span the 3m without an intermediate support. Will this be OK, or should I put a post support in half way ? Should I support every joist, or ever other joist ?
What should be the spacing of the posts on the outer frame ?

 

[Whatmuff]

Hey

I would put more support in if I were you, 3m is a long way! I put supports in on mine very 800mm so two joists and then one side was bolted to the house wall and then used 4x4 posts for support. Don't forget to support the centres too. Use plenty of noggins and good quality exterior screws.

If your raising the deck consider using block and concrete foundations instead of concreting wooden posts in the ground as eventually they will rot! If you watch the yanks do it, they use 6x6 posts and 10x2 joists and 1m deep concrete footings for each support, slightly over engineered if you ask me but expensive!

 

[gingerneil]

Here's the latest plan. I think I'm going with posts concreted in, but bitumen painted.

 

[Whatmuff]

Looks good that! Best of luck

 

[beatts]

I built a 5m x 3m deck last summer and put probably twice as many support posts in as that, but then I do tend to be a bit OTT sometimes.

What I have now though is a solid as a rock deck with no spring or bounce at any point. )