Attic insulation recommendations

[jmlcolorado]

So I'm looking to insulate my attic. It's about 990 sq ft.
I think current standards for living spaces is R38. Would it hurt if I went above any begone and insulated to R60 for only another couple hundred bucks?

 

[jimp]

Theroetically anything over R 30 is a waste, see graph.

However, due to air infiltration, moisture and poor installation practices, higher R values are practical.

I used R 60 in my roof for the above reasons and your reason (did not cost much more). I would think R 60 would be the max and that is likely wasteful.

 

[Falcon67]

If I had the extra cash, I would fill the joist bays over my R13 batts with blown. That'd be about 11" total in those 2x12 bays. Not so much for extra insulation as for air infiltration. The batts fit tight, but not that tight. Still, R13 works well enough. We FINALLY got a "cold front" and some rain, so it got into the 50s Wednesday night, max yesterday was 62, mid 50s this morning. The shop with R13 walls, R13 attic, vented attic space and unsealed OSB on the ceiling was still 77F.