I am insulating my garage roof with polyiso board in between the 2x4 truss rafters. I plan to use foil tape to seal the seams. It will stick fine to the new insulation. But how can i clean the old rafters so the tape will stick. They are fairly clean not real dusty, no spider webs but touch them and my hands get real dirty real fast.
I am hoping to do it from the ground as much as possible.
Maybe a sponge mop and soap. A roofing tar brush?
Bill D