Mix 800g of Intergrain UltraPrep Mould Killer into 8L of water, and stir until powder is fully dissolved. Warm water will help dissolve the powder faster.
Scrub onto the entire area with a stiff bristle brush. Leave for 15 minutes, do not allow it to dry on the timber, add more product if required to keep it wet.
Rinse off exterior surfaces thoroughly using maximum pressure from a garden hose or use a high-pressure water cleaner. For best results, a high-pressure water cleaner is recommended. If any visible mould remains, repeat the process.