noggins and where to use them

[happyhero]

Hi I am building a bit of a robust shed (8'x20') out of mainly 4"x2" treated timber and I have constructed the base framework but before I cover it I just wondered about noggins, do I need to put them in a floor, I haven't spotted any in my house under the floorboards, so are they just for walls?

What is their main purpose, I understand that you can place them strategically so that they tie in with any sheet edges for fixing purposes, but is their main purpose not to stop the timbers twisting?

If I should put them in, bearing in mind the joists span the 8' length, where/how many should I put in?

Any info appreciated, and apologies if the question is a bit basic.

 

[big-all]

assuming your on around 2ft centres and you aint using plasterboard i wouldnt bother as the span is small
with plasterboard its only to support the edges on the joins

 

[happyhero]

Ok cheers for the info big-all, they are actually at 400mm centres and 18mm WPB ply on top so I will leave the noggins out.