Overview
GRP is fairly stain-resistant if cleaned promptly. Bird droppings and tannin marks are the trickiest.
Symptoms
- Localised marks that won't come off with water.
Common causes
- Bird droppings.
- Tannins from wet leaves.
- Sap.
- Rust runs from hardware.
When to call a professional
- Stains that won't lift after two attempts.
Prevention
- Wash monthly, especially under bird perches.