R 30 for an area that reaches zero is below code in my area of the
midwest. R 35 is usualy a minimum code in zone 5. R35 are minimum code
requirements, key word is minimum, to keep you from going broke to pay
your utility co.. You should be looking at R 60- 70-R 80+. I upped my
attic to R 100- 110 and second floor temps went up 5f. Old standards
need to be upgraded in this area. Also insulation settles and
fiberglass looses efficiency as it get cold. Perhaps as much as 25% at
Zero. Measure what you have in inches and calculate your true R and
put in alot more. How cold does it go in your area.