How to Prep a Fiberglass Roof for a Roof Coating

What You'll Need
Water Jet Power Washer
Mild Detergent
Nylon Scouring Pad
Oxygen Bleach
Commercial Fiberglass Cleaners

A new fiberglass roof can have a  roof coating applied immediately, without special prep. Prepping the roof, however, is necessary for an older fiberglass roof that has been stripped of protective coating, has become oxidized, darkened to a grayish color and stained by molds and mildew. Here are some steps to clean the mess up before applying any coating.

Step 1 – Assess the Degree of Cleaning Needed

The cleaning process and the chemical cleaners needed depend on the overall status of the fiberglass roof. If the roof has a lot of dirt and grime on it, a power washer may be needed to do the trick. This may also require the help of a mild detergent and a scouring pad or brush. Make sure that the brush is not too stiff, to avoid damaging the surfaces of the roof.

Look for dark patches or grayish contaminations. This is probably a sign of mold infection. Mold infection requires a more powerful cleaner: oxygen bleach. If the fiberglass is highly oxidized and has uneven color patterns, try using a commercial oxidation remover and color restorer.

Step 2 – Cleaning the Roof with a Water Jet, Detergent and Scouring Pad

A water jet power-washer is a simple to use device that can be connected directly to a garden hose. Connect the device to the water hose and climb up the roof to begin cleaning. Wear slip-resistant shoes to avoid falling. Begin by spraying water all over the roof to dampen it. Do not use too much pressure just yet. Just allow the water to soak the roof and loosen any dirt and grime.

When the roof is all wet, increase the water pressure and power spray every surface until a cleaner surface is revealed. Dip a scouring pad in soapy water and use it to scrub tough stains.

Step 3 – Using Oxygen Bleach

For molds and mildew stains, mix a good amount of oxygen bleach in a bucket of water. Check the product info for mixing directions. Spray the entire roof with the solution and let the bleach sit for about 10 minutes. If the weather is sunny, 5 minutes will do. Scrub the fiberglass roof surface with a nylon scouring pad or a brush. Wash off the bleach from the roof. If there are still molds and mildew stains, repeat the process. Make sure to rinse the roof thoroughly with water after application.

Step 4 – Using Commercial Fiberglass Cleaners

If the fiberglass roof is highly oxidized and has uneven color tones, look for a good oxidation remover and color restorer product in the market. Apply the product onto the roof according to manufacturer’s directions. Before using any commercial products, make sure to clean the roof first with any of the methods stated above. When the roof is dry and free from stains, the coating can now be applied.