Duct Insulation R Value Requirements

R value based method of section c402 1 3 u c and f factor based method of section c402 1 4.

Duct insulation r value requirements.

Allison bailes of decatur georgia is a speaker writer building science consultant and the author of the energy vanguard blog. Add insulation to attic. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation. And that means it s time to deal with duct insulation in a more meaningful way than just increasing the required r value to 8 for ducts in attics.

Existing 3 4 inches of insulation. You can follow him on twitter at energyvanguard. The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures. The following information applies to combined heating and cooling ducts in zone 4 areas.

Or component performance alternative of section c402 1 5 roof solar reflectance and thermal emittance fenestration in building envelope. R value of 3 5 is required for buried ductwork and ducts installed in an unvented attic. Insulation r value to match the supply duct. For example if you have a type of insulation that has an r value of r 5 per inch of thickness you will need a depth of 6 inches of this insulation installed your attic to reach r 30 if you live in zones 2 or 3.

Ashrae 90 1and the ieccboth require r 6 insulation for ducts in unconditioned spaces and r 8 or r 12 depending on the climate zone for ducts installed outside the building. R value of r 6 is required for exterior ductwork or ducts installed in a ventilated attic or an unvented attic above a. Specific insulation requirements of section c402 2 thermal requirements of either. If the lesser r value most likely the duct r value is chosen the envelope of the building must be shown to comply with a performance based option.

Recommended insulation levels for retrofitting existing wood framed buildings.