As to damaging the material, depends on how the knee pads are constructed on the inner portion. But, I wear knee pads a lot around the house and outside when doing projects and I have a heck of a time keeping them on. They seem to pop off or slip down when they want to and that is when they are strapped onto my knee with only jeans or sweats under them. Seems to me that the heavy material used in waders would really cause knee pads to move around. Lots of luck and hope you find a good solution. Larry ---sagefisher---