TOPIC: Insulating ducts in an unconditioned space in the Northeast

Although the Standards explains the following:

Heating ducts located in an unconditioned space (let's say in an attic)in the Northeast should be insulated.  It is also understood that the vapor barrier is not needed because the duct acts as its own barrier. 

The Standards also explains that A/C duct work in an unconditioned space in the Northeast should be insulated with a vapor barrier on the outside.

I am curious as to the opinion when the duct work,in an unconditioned space in the Northeast, is used all year for both heating and A/C, what is the recommended set up for insulating ducts and incorporating a vapor barrier.

Assume the attic reaches 20 degrees in the winter, and up to 100 degrees in the summer.

What standards are you referring to? The IRC?

www.certainteed.com/products/insulation/index/317380

Thanks Jeffrey.  I will call SoftTouch and talk with them about ducts being used for both heating and AC.

From the "Technical Information" tab at the link above:

BASIC PRODUCT DATA
Duct Wrap may be used to insulate most heating, ventilating and air conditioning ductwork at temperatures from 35°F to 250°F (1.7°C to 121°C) for faced duct wrap, and from 35°F to 350°F (1.7°C to 177°C) for unfaced duct wrap. The FSK and white PSK facing have a 0.02 perm rating. The gray PSK has a 0.09 perm rating.

COMPLIANCES
Duct wrap products meet the requirements of the following current specifications and standards:

•Material Specifications ASTM C 1290, ASTM C 553. The FSK facing meets the requirements of ASTM C 1136, Type II.
•Fire Safety Standards NFPA 90A, NFPA 90B
•Model Building Code ICC
•GREENGUARD® Children & Schools