Roof washing and roof cleaning are often used interchangeably in Surrey, but there’s an important distinction: professional roof cleaning uses a soft-wash approach — low-pressure application of biodegradable biocide that kills moss, algae, and lichen without damaging shingles. Pressure washing (power washing) a roof is contraindicated and voids most asphalt shingle manufacturer warranties. This guide covers what professional roof washing costs in Surrey BC, how it’s done correctly, and what to avoid.
Professional soft-wash roof cleaning Surrey BC: I-M Roofing Ltd. — 236-838-9577
Roof Washing Cost Surrey BC — 2026
| Home Size | Soft-Wash Cleaning Cost | With Zinc Strip Add-On |
|---|---|---|
| Small (under 1,500 sq ft footprint) | $400 – $650 | $550 – $850 |
| Standard (1,500–2,500 sq ft) | $550 – $850 | $700 – $1,100 |
| Large (over 2,500 sq ft) | $750 – $1,100 | $950 – $1,400 |
The Right Way to Wash a Roof in Surrey BC
Soft-wash method (what we use):
- Application of biodegradable biocide solution at low pressure (garden hose equivalent) using an extension wand from the eave edge or ground. The solution penetrates moss rhizoids and kills the organism at the root.
- Allow dwell time (typically 20–40 minutes) for the solution to kill the moss. Some contractors finish here and allow rain to wash residue — this is acceptable for heavy moss coverage where immediate cosmetic result isn’t required.
- Optional gentle rinse with low-pressure water to remove dead moss material. For moss coverage over 30%, we may hand-brush the surface with a soft bristle brush before rinsing — this speeds the cosmetic result but is not necessary for the biological kill.
- Zinc strip installation at the ridge (recommended as an add-on) — zinc ions in rainwater runoff inhibit regrowth for 5–10 years.
Pressure washing (what damages roofs):
High-pressure washing removes moss mechanically but in doing so strips granules from asphalt shingles. Granules are the asphalt shingle’s UV protection — removing them exposes the asphalt mat directly to UV, significantly accelerating deterioration. GAF, IKO, and Owens Corning all explicitly void their manufacturer warranties if the roof was pressure washed. Never hire a contractor who power washes asphalt shingle roofs.
How Often Does a Surrey BC Roof Need Washing?
- Low canopy (no trees overhanging): every 5–7 years when moss visible
- Moderate canopy: every 3–5 years
- Heavy canopy: every 2–4 years
- With zinc strip installed: extend interval by 2–3 years at each cycle
Related Resources
- Roof cleaning service page Surrey BC
- Moss removal DIY vs professional Surrey BC
- Annual roof maintenance checklist Surrey BC
Book a soft-wash roof cleaning: 236-838-9577
