On rubber roofs toh general contractor tom silva patches small holes with a regular bicycle tire repair kit.
How to clean a fibreglass flat roof.
The simplest way to clean your grp roof after getting rid of all the leaves and debris is with a yard brush and some hot soapy water.
How to clean a fiberglass roof.
Fibreglass roofing cleans readily if regularly maintained sweep the roof clear of any debris leaf fall etc.
Step 2 application.
If you can safely access it then the simplest way to do that is by simply using a long handled mop and a bucket.
Make sure that this is removed responsibly not just thrown over the edge as this will cause blocked gutters or worse a danger to passers by use a clean brush to wash the roof off with warm soapy water.
Step 2 use chlorine bleach to spot clean especially troubled areas.
Invest in a roof cleaner to remove stains and growth from your flat roof.
After this mix 1 gallon of warm water with cup.
A garden hose is just as effective.
Cleaners specifically designed for this purpose unlike chlorine based bleaches better penetrate the shingles to stunt growth without causing dangerous chemical runoff.
Step 1 preparation.
Cleaning your grp roof first of all if you want to maintain its good as new appearance then a little cleaning is necessary from time to time.
A pressure washer can be used for less labour intensive work.