Remove all loose rubber and caulking material from the roof of the motor home using the scraper and wire brush. Sweep the loose debris from the roof and place it in a trash bag. Scrub the roof using soapy water, the scrub brush and a cotton mop. Allow the roof time to dry.
Carefully check the roof for holes, and patch them using the roofing cement after the water dries on the roof. Allow the roofing cement to dry thoroughly according to manufacturer instructions for the brand that you choose. Sweep and mop the roof again and allow it to dry overnight.
Mix the liquid rubber roof compound in a bucket according to the manufacturer instructions for the brand you are using. Mix the compound thoroughly using the drill and mixing attachment. Spread the liquid roofing compound around all vents and flashing on the roof using the paintbrush.
Pour liquid roofing compound onto the roof in small sections and spread it evenly across the surface using the paint roller. Repeat the process until the entire roof is covered. Allow the compound to cure for at least 24 hours before you attempt to use the motor home.