Mildew and mold can be cleaned with a mixture of bleach and water.
How to clean pergola roof.
If you haven t washed your once prized pergola in months or years or even if it s just high time you deep cleaned you may be in for a chore.
Here is a link for the thompson s water seal i used.
Regular clean ups will ensure that these stains are tackled and your pergola looks elegant all through the year.
In a bucket combine some cold or warm water with some liquid dishwashing soap the kind you use for washing.
It sounds like you ve let it go for a while so you might have to hit it with something a bit harder.
Gently wash your pergola with soap and hot water in sections.
To remove stains and mildew mix a cup of vinegar oxygen bleach with a gallon of plain water and apply it on the stains soon after hosing down your pergola.
You want to keep the bleach concentration low to avoid staining or damaging the wood.
If it needs cleaning you can use a low pressure power washer to clean away any debris or mud.
Most manufacturers and installers seem to recommend to clean your polycarb roofing pretty regularly with warm soapy water and a soft brush.
Rinse immediately after each section.
Leave it on for a few minutes and use a brush to gently rub the stains off.
Take a garden hose and give the entire aluminium pergola a good hosing down from top to bottom.
If this doesn t work you can sand the pergola and apply a fresh layer of stain and sealant.