[ChrisKingston]

Hi,

I am trying to put in some new beams to hang a ceiling off, I will put them in between existing ceiling joists so I can weave acoustic matting between the old and new joists.

So the new joists are only going to hold up the ceiling, they will not touch the floor above and there will be no other load on them at all. I may put two layers of plasterboard (and a skim) over them, but that is all the weight they will need to hold. But I don't want sagging or cracking, so my question is: what size timber do I need?

The longest span is 3800mm, and the joists are spaces every 350mm. Will I get away with 4" x 2", or do I need something meatier?

Thanks,
Chris