Stubborn black spotty stains are probably mildew.
How do you clean house siding.
Start at the bottom to avoid streaking and use your garden hose to rinse off each section before it dries.
Use a bleach cleaning solution.
As an experiment rub a clean white cloth across the unwashed siding.
Basic vinyl siding cleaning apply the vinyl siding cleaning solution with a soft bristle cleaning brush scrubbing the full length of each lap.
Clean the area with a solution of one part bleach to four parts water.
For a stronger solution mix together one third cup powdered laundry detergent two thirds cup powdered household.
Pour multi use soap that is formulated for pressure washers into the reservoir.
Get the details right.
Some good vinyl sider cleaner solutions include.
But over the years your house will experience paint failure faster than if it were applied to clean siding.
Install the soap tip to the end of your pressure washing wand.
Then to pressure wash the house siding clean use either the 25 or 40 degree nozzle tip.
70 water 30 white vinegar makes a great all purpose vinyl siding cleaner that removes light mold and mildew stains.
Check the packaging to make sure the soap is safe for siding windows and sidewalks.
To pressure clean the higher up areas you will want to use an extension wand because you want to avoid using a ladder with a pressure cleaner.
Homemade mold cleaning recipe for siding cup trisodium phosphate tsp cup powdered laundry detergent 1 quart household chlorine bleach 1 gallon water.
What you need to clean vinyl siding store bought vinyl siding cleaning products clorox windex lysol etc soft cloth long handled soft bristle brush hose buckets of water pressure washer optional.
Always hold the pressure wand 3 feet from the surface to start and move closer to 1 foot as you watch how much.
Use a vinegar cleaning solution.
Repainting the patch to match your siding will be up to you.
If you are.
The cloth will likely come up dark gray with a layer of fine soot.
Dab the area with a little diluted bleach if the black disappears it s mildew.