How do you repait semi trailer roof?

Before you start any RV roof repair work, you need to clean the roof first. Clean the RV roof from any dirt, debris, loose material and oil and grease residues. A power wash might be the right thing to use for the job. However you can also perform the RV wash using hand by using mild detergent and a bristle brush. Once the roof is cleaned, you need to patch up large holes or cracks before you apply any RV roof repair coating e.g. Liquid Roof. This is the right way to go. Once the larger holes are patched up, then you can apply Liquid Roof to finish with RV roof repair.