I have built a decking sub frame using 6 x 2's, 4 rows of main joists spanning approx 4m, fixed and secured to 8 posts with a ledger plate and joist hangers off the back of my garage. I have secured my inner joists using 100mm coach screws (3 on each end of the inner joists). The inner joist are all roughly 1.2m in length, all 400ctrs appart with a noggin placed up the middle. Is one noggin enough or do I require more?

I would say it is strong enough, but I tend to be a bit over cautious when doing these things and can go OTT.

Thanks

Should have mentioned, the total area is 3.2m x 4m approx

nog twice being outside will prevent any twisting

Are your joists in at 400cm or did you mean 400mm?, as long as you set your joists at least 600mm centres you will be fine

It is all done chaps, the inner joists were set at 400mm/40cm with noggins filling the gaps.

The decking turned out well!

Just got to get some screening for the back of the garage to finish it off.