How to Remove Black Spots From Fiberglass RV Roof

How to Remove Black Spots From Fiberglass RV Roof
Over time, dirt accumulation leaves black spots and chalky oxidation on fiberglass RV roofs. Periodic cleaning (once every three to four months) is required, which also will help protect the gelcoat resin surface. Gelcoat is a thick, hardened protective resin RV manufacturers apply over the fiberglass to give it a shiny, rich color. Regular and gentle cleaning keeps fiberglass RV roofs looking new and in good condition.


Difficulty: Moderate

Things You’ll Need:
  • Deck shoes or shoes with a non-slip sole
  • Soft-bristled brush broom
  • Five-gallon bucket
  • Mild household cleaning detergent
  • Sponge mop
  • Garden hose
  • Black streak remover product for fiberglass RV roofs
  • Fiberglass-safe car or RV wax
Step 1
Put on a pair of deck shoes or other shoes with a non-slip sole to prevent slipping while on the RV roof.
Step 2
Sweep loose debris off the roof using a soft-bristled brush broom.
Step 3
Fill a five-gallon bucket with a cleaning solution made of a mild household cleaning detergent and water. Follow the cleaning detergent label for mixing measurements.
Step 4
Bring the bucket of cleaning solution and a household sponge mop or a soft-bristled brush broom onto the roof.
Step 5
Wash the roof using the mop or broom and the cleaning solution. Start cleaning at the end of the fiberglass RV roof that is farthest away from the RV's ladder and work your way to the end of the roof near the ladder. Regularly dip the mop or broom in the bucket of cleaning solution to resaturate the mop or broom head with detergent.
Step 6
Rinse off the cleaning solution by spraying the fiberglass RV roof with a garden hose. Stand at the top of the RV's ladder while spraying off the roof with the hose. Avoid standing on the roof, which will be slippery while it is wet. Climb down the ladder and let the roof completely dry.
Step 7
Rewash the fiberglass RV roof using a black streak remover product, available for purchase at RV supply stores, if the household detergent failed to remove the black spots. Choose a black streak remover product designed for fiberglass roofs and use the product sparingly to avoid damaging the roof's gelcoat resin. Follow the manufacturer's directions on the black streak remover product label to remove the black spots.
Step 8
Protect the fiberglass RV roof from oxidation and restore the shine of the RV roof by applying a layer of wax. The process of washing a fiberglass roof removes the previously applied polish or wax. Use car wax or RV wax, as long as it is a product designed for use on fiberglass. Follow the manufacturer's directions on the wax product label to apply the wax.

Tips & Warnings

Black spots or streaks on an RV roof develop after dirt is allowed to remain on the roof for an extended period of time. Avoid the future formation of black spots and streaks by washing and waxing the RV roof every three to four months.
Black streak remover products for RV roofs are harsh and should only be used as a last resort, when regular cleaning fails to remove black spots from an RV roof.

Article Written By Rose Kivi

Rose Kivi has been a writer for more than 10 years. She has a background in the nursing field, wildlife rehabilitation and habitat conservation. Kivi has authored educational textbooks, patient health care pamphlets, animal husbandry guides, outdoor survival manuals and was a contributing writer for two books in the Uncle John’s Bathroom Reader Series.

Don't Miss a Thing!

All our latest outdoor content delivered to your inbox once a week.



We promise to keep your email address safe and secure.