Leave it on for a few minutes and use a brush to gently rub the stains off.
How to clean pergola roof.
Take a garden hose and give the entire aluminium pergola a good hosing down from top to bottom.
This works best if the hose is on a.
You want to keep the bleach concentration low to avoid staining or damaging the wood.
Rinse immediately after each section.
How to clean an aluminium pergola.
In a bucket combine some cold or warm water with some liquid dishwashing soap the kind you use for washing.
Most manufacturers and installers seem to recommend to clean your polycarb roofing pretty regularly with warm soapy water and a soft brush.
If it needs cleaning you can use a low pressure power washer to clean away any debris or mud.
If this doesn t work you can sand the pergola and apply a fresh layer of stain and sealant.
But your hard work will pay off.
Mildew and mold can be cleaned with a mixture of bleach and water.
Gently wash your pergola with soap and hot water in sections.
It sounds like you ve let it go for a while so you might have to hit it with something a bit harder.
Here is a link for the thompson s water seal i used.