Fred & Gerry's Exterior Cleaning Formula
2/3 cup TSP or TSP substitute
1/3 cup detergent
1 qt. bleach
3qt. warm water
The TSP substitute works the same as TSP except it has no phosphates, phone around to your local paint and building supply stores first as it's not available in all outlets, it's environmentally friendly.
You can use any type of detergent you want, dish, laundry; the soap acts as a carrier for the other ingredients.
Use a garden sprayer, dampen down the area you want to clean with your garden hose first, spray on the cleaner and let it stand for about 15 to 20 minutes, do not apply in direct sunlight.
Take a broom and scrub to really dirty areas and then hose off.