I need to get rid of the build up of leaves and other things that have built up in the valley of my low sloped metal roof. It is easy enough for me to get up on it. I would use a leaf blower and a broom if needed. As odd as this may sound, but when is a good time to go up on the roof so that it is not slippery from dew or other moisture. I know wait after a rainfall, but as it is not an asphalt roof with the sand on it to provide good traction.