Can Pressure Washing Damage Siding or Decks?

Yes — pressure washing done incorrectly can cause real damage to siding, decks, and other exterior surfaces. Here's what can go wrong and how we prevent it.

Damage from Too Much Pressure

High pressure (3,000+ PSI) on soft or older wood siding can raise the grain, leave streaks, and drive water into wall cavities. On painted surfaces, it can strip paint prematurely. On older composite or aluminum siding, it can dent or delaminate surfaces. On older homes in Brookline and Cambridge with original clapboard siding, incorrect pressure washing can cause real damage.

Soft Washing for Sensitive Surfaces

Soft washing uses lower pressure (200-500 PSI) combined with cleaning solutions that kill mildew and algae chemically rather than blasting them off mechanically. The result is just as clean with far less risk of surface damage. We use soft washing on older wood siding, painted surfaces, and any surface where high pressure is a risk.

Protecting Landscaping

Runoff from pressure washing can carry cleaning chemicals into landscaping and storm drains. We wet plants before and after washing to dilute any chemical contact, and we use products that break down safely in the environment when possible. The EPA's Safer Choice program lists certified products for exactly this situation.