We have run into some problems with our new home's HVAC. Indiana has adopted IRC 2018 code requirements. Can anyone help us understand the duct requirements for exhaust ducts? We have R4.2 running through unconditioned spaces. We also have a dryer vent connected to flex duct - not smooth interior metal as the IRC M1502.4.1 seems to specify.
Will we have problems with flex duct used for our dryer vent as shown in this photo?
The dryer duct is rigid/smooth metal as it goes vertically up the wall, but it changes to R4.2 flexduct as it goes through our garage ceiling and up out of our roof. I also think it extends more than the maximum 35' - especially if you have to subtract length due to bends in the duct.
Let me know if anyone has experience with code requirements in this area.