I am considering using some SDR 13.5 duct where I have always used SDR11 before.
The DR stands for diameter ratio. Ratio between wall thickness and outer diameter (I think). Higher numbers mean thinner wall thickness. Others use the 13.5 unless they get into rocky areas. I am a bit gunshy as the cost is only about 2 cents per foot different. Anyone here have any experiences they can relate?
