You will need a Gutter Scrub / Whitening if you have black or grey tiger stripes on the exterior of your gutters. A Gutter Scrub is a very complex and tedious service. Here at Wall 2 Wall, our techs use an F-13 Solution that is mixed & diluted with water but is still very strong. It has to be above 70 degrees for the chemical to work. Please refer to the “Premium House Wash” on your estimate that we emailed you. This service automatically comes with an exterior house wash due to the rinsing of the agent.