Never walk directly on a slate roof slates can easily be broken by stepping on them. X Research source It's best to walk on a roof when the sun is out and morning dew has evaporated.
Even a mild slope can be dangerous to walk on if the roofing material is slippery, gritty (worn composite shingles), or loose (wood shakes or any worn shingles). Do not walk on a wet or icy roof, a very steep roof, or one with obvious structural damage. Climb up a ladder without your tools to take a look at the roof surface.
