Attic Ductwork R Value

R value measures how well certain building insulation materials can resist heat.

Attic ductwork r value. Not sure where you are at but here in florida the minimum r value for ducts installed in an attic or any unconditioned space is r 6. Look at your ductwork. Table 1 shows effective r values for 8 inch round ducts at three attic insulation levels and three duct insulation levels r 4 2 r 6 and r 8. Recommended insulation levels for retrofitting existing wood framed buildings.

Return ducts ductwork that brings expended air back to the hvac system to be filtered reconditioned and redistributed require insulation with an r value of 3 5 for exterior ducts and ducts in a ventilated attic or unvented attic above an insulated ceiling. The effective r value of a buried duct installation depends on the size of the ducts the r value of the duct insulation and the depth of the loose fill insulation. When determining how much insulation you need don t guesstimate calculate. Here s how that 3 500 sf house would come out with those.

He d add open cell foam below the roof deck to give the assembly the required r value but the bids range from 40 000 to 60 000. Add insulation to attic. Know exactly how much you need with our project calculators. The duct insulation r values i mentioned above are what s on the product label.

The higher this value is the better you can expect the insulation to perform. If the insulation is a foam board or sprayed on foam use any visible label information or multiply the thickness in inches by 5 to estimate the r value. Ducting values are determined by two factors. How often do you think you get the full labeled r value.

Existing 3 4 inches of insulation. I m looking at you mississippi and alabama r 6 and r 4 2 are common r values for ducts. 7 948 btu hour 0 66 ton the numbers are even higher for the additional heating load. Or you live in a state that doesn t require r 8 on ducts in attics.

It will most likely be a fiberglass batt so multiply the thickness in inches by 3 2 to find out the r value or the r value might be visible on a product label. Was your ductboard existing and you added a zoning system. The mass of the insulation consisting of both its density and thickness and the compression ratio at installation which determines the final compressed density and effectiveness of the insulation. If it was you don t have much recourse.

Some other factors to consider. R values represent the heat resistant properties of an insulating material. It comes down to three options the first of which is to convert his attic into a conditioned space by installing 4 1 2 inches of polyiso insulation above the roof deck and then adding a new standing seam metal roof. 6 305 btu hour 0 53 ton r 4 2 duct insulation.