7 Common Exterior Cleaning Mistakes to Avoid

Using too much pressure is the most common mistake in DIY pressure washing. It's tempting to crank the pressure up for what feels like a more powerful clean, but excessive pressure damages surfaces — it strips jointing sand from block paving, scours the surface of natural stone, and can crack or chip softer materials. More pressure is not always more effective, and getting it wrong can mean expensive repairs.

Using the wrong cleaning products for the surface type is another common error. Strong acids damage natural stone. Bleach-based cleaners can cause colour changes on some surfaces. Alkaline cleaners affect certain sealants. Always check that a product is appropriate for your specific surface before using it. If in doubt, use a neutral pH cleaner and test on an inconspicuous area first.

Neglecting to treat the underlying cause is a mistake that leads to rapid regrowth. If you pressure wash algae and moss without applying a biocidal treatment to kill the root systems, regrowth will begin within weeks. Professional cleaning typically involves pre-treatment, thorough cleaning, and often a post-treatment biocide or sealant to slow regrowth. Skipping any of these steps reduces the longevity of the results significantly.