Duct Insulation R Value Requirements

Recommended insulation levels for retrofitting existing wood framed buildings.

Duct insulation r value requirements.

Insulation r value to match the supply duct. 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. 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. Ashrae 90 1 also has a requirement of r 1 9 for supply ducts installed in indirectly conditioned spaces which includes plenum spaces above ceilings.

Allison bailes of decatur georgia is a speaker writer building science consultant and the author of the energy vanguard blog. 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. 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.

Insulation r value must meet either the requirement for above grade walls or for exterior ducts. 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. You can follow him on twitter at energyvanguard. Specific insulation requirements of section c402 2 thermal requirements of either.

R value of 3 5 is required for buried ductwork and ducts installed in an unvented attic. 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. Add insulation to attic. R value based method of section c402 1 3 u c and f factor based method of section c402 1 4.

The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process.