What gentle of insulation do i entail when remodeling? I am putting ceiling tiles stapled onto 1x4 furring strips and i...

I am putting ceiling tiles stapled onto 1x4 furring strips and i have r-25 rolled insulation short a vapor barrier i.e. 8.5 inches thick.I have planned on laying the insulation between the rafter and then across the rafter the other way for a total of 17 inches of insulation which i hold been told is more than ample.My concern is that there is almost an 8.5 inch gap between the furring strips and i didnt know if that would be plenty support for the rolled insulation.I had planned on putting up the insulation and later installing the tiles.Would it be too much weight on the tiles and brand name them bow over time?Should i have purchased it next to a vapor barrier?Is a vapor cordon needed in ceiling insulation?
Answers:    As I read between the lines it, you nailed the furring strips to the bottom of the ceiling rafter perpendicular to them? Then they will suffer the weight of the insulation and the tiles will not be artificial.

No, you don't need a vapor handrail. Just keep the roof within good repair so you don't gain leaks. Getting wet into that much insulation will be a mess!
ceiling insulation needs to be atleast an R-30, 91/2 inches sticky......if u nailed the strips beside # 8 framing nails or screwed them to the jois next they should hold up the insulation on them...

lic. gen. contractor