Many travel trailer roofs are coated with a rubber material, but there are many other materials used. To be safe when cleaning your roof, never use solvents, citrus-based cleaners or products containing petroleum in any form. Instead, use a mild detergent (such as dishwashing liquid) along with a medium-bristle brush. Some experts recommend spraying the sides of your RV with water before rinsing the detergent off the roof in order to avoid streaking or damage to the travel trailer's exterior finish. Water can highlight small holes, so make a detailed visual inspection immediately after rinsing to check for holes along seams.
This was part of one of our manuals....I guess this means we can walk on our roof, using common sense and not abusing it. Did not come with a ladder but we bought one. It did say to not use a power washer.