If you have a travel trailer or other RV you know how filthy these can get on the roof. You need to clean the roof regularly to inspect for damage to the seals and for potential leaks. Cleaning tree sap, mold and other common soils can take a long time, can be dangerous and can damage your roof.
Why not save yourself all this trouble just by keeping your RV or Camper covered with a high quality vinyl tarp? Now all you have to do is take the tarp off once a year (just before or after a camping trip is a good time to do this since you already have the tarp off anyway).
If you have room on your grass, this is the ideal location but make sure you don't do this soon after cutting the grass otherwise you will end up with lots of grass clippings sticking to the tarp. If you don't have room to lay out the whole tarp you can also clean it in sections. You can also lay it out on your driveway but be sure to sweep it well first to avoid walking on the tarp with stones or other sharp objects beneath the tarp.
Preferably you should use a mild detergent such as dish detergent but if there are stubborn stains you may need to use something stronger such as Mr. Clean but use this sparingly. Murphy's Oil Soap is also a good vinyl cleaner. Avoid products with bleach since this will deteriorate the stitching in the tarp.
For stubborn stains you can try making a DIY cleaner using three parts baking soda with one part water. Add a few drops of dish soap or Murphy's Oil Soap and mix this into a paste. Rub this paste over the stains using a clean rag or a brush.
You can scrub the tarp on your hands and knees using a normal brush but if you have a brush that can be attached to a broom handle this is ideal.
After you have finished scrubbing, rinse the tarp with a garden hose to get all of the soap and debris off. Be sure to dry the tarp well before putting it back on your RV. Moisture trapped under the tarp could cause mold to form. If you don't have an outdoor railing or line you can dry it on you can set it on your driveway until the top side dries completely then flip it over to dry the underside.
Avoid dragging your tarp across your driveway since the asphalt or stone is very abrasive and can cause damage.