I've recently started putting in a new bedroom in the attic of my house. Currently, there are 2x4 24" oc ceiling just. I plan to lay 2x6 16" oc to allow a low cost and more headroom. The maximum span is 6' and load is 30 psf. Is this allowable in most places? I can't get a hold of the building inspector so I'm asking others.Input is appreciated.