Check sprinkler overspray, leaking gutters, shaded vegetation and downspouts. Note whether growth is on vinyl, painted siding, masonry or wood because each material needs a different cleaner and application.
Find the moisture source
Check sprinkler overspray, leaking gutters, shaded vegetation and downspouts. Note whether growth is on vinyl, painted siding, masonry or wood because each material needs a different cleaner and application.
Clean gently and test
Remove loose debris and protect plants. Test a siding-approved cleaner in a hidden spot, apply only as directed and rinse gently from top to bottom. Do not blast water upward under laps or into vents and window seals.
Reduce regrowth conditions
Trim vegetation only where appropriate, correct irrigation aimed at the wall and maintain gutters. Persistent dampness can signal a drainage or leak issue that cleaning alone will not fix.
Salt Lake Valley note
Shaded walls can remain damp longer after irrigation or storms, even in a generally dry climate. Compare the affected wall with sunnier elevations and address repeat wetting before scheduling another wash.
Common questions
Can bleach be used on siding?
Only if a product label and siding manufacturer permit that use, at the stated dilution and with plant/runoff protection. Never mix bleach with ammonia, acids or other cleaners.
When should I call a professional?
Call when growth covers a large or elevated area, siding is fragile or oxidized, or the source of persistent moisture is unclear.