Deck feels springy

[dowzer]

I have built the frame and fitted the newel posts for a new 4.2m x 3m deck - it is surface mounted but, as the back is lower than the front, the back has been raised about 6" and the slope is fairly constant (i.e. at the mid point the joist is around 2 - 3" off the ground.

I have used 6" x 2" spaced 500mm apart but when I walk on it the whole deck feels a little too springy. I haven't screwed the boards on yet as I want to be sure I don't need to do anything else first.

Are the boards likely to make a difference i.e. spread the load the opposite direction to the joists? Also will the deck get a little more rigid when it has been in place for a while and the joists dry out and settle?

I want to avoid having to put in ground posts if I can so are there any other options? If I was to support the deck at a few mid points using paving slabs or blocks bedded on concrete?

Thanks
Jason

 

[r896neo]

Whilst the boards will help a bit If its springy now it will stay that way so do something about it now while its easy.

Supporting on blocks etc mid span would be a good option if you don't want to use posts.