Spokane commercial roofs often sit under heavy winter snow loads followed by spring melt that feeds moss and algae on TPO, EPDM, and modified-bitumen surfaces. These growths hold moisture against seams and flashings, shortening membrane life in the freeze-thaw cycles typical along the South Hill and near the Spokane River. Effective cleaning starts with a walk to locate clogged drains, ponding areas, and HVAC curb leaks before any water is applied.
Low-pressure washing combined with EPA-approved roof-safe detergents lifts organic material without driving water under laps or damaging granule surfaces on modified roofs common in older downtown buildings. Crews bag and remove debris rather than rinsing it into gutters that already struggle with cottonwood fluff each June. After cleaning, a zinc-based treatment slows regrowth for the next two seasons in Spokane’s damp climate.
Edge details such as parapet walls, skylight curbs, and scuppers receive extra attention because wind-driven debris collects there and blocks flow during the heavy November rains. Final inspection includes photos of each cleaned section so property managers can track condition year to year.
Technician insight
In Spokane, the thing that catches most people out with Commercial Roof Cleaning is how quickly moss returns on north-facing sections of older flat roofs downtown once the cottonwood season ends; skipping the zinc treatment means you are back on the roof the next spring.
North Monroe Street Office Building
Heavy moss covered the EPDM roof and blocked two scuppers after the previous winter’s melt. We removed the growth, cleared the drains, and applied treatment. Water now flows freely and the membrane dried out before the next freeze.
Commercial Roof Cleaning Services We Offer
✓Moss and Algae Removal
Kills and removes organic growth on commercial membranes and metal panels common in Spokane without high-pressure damage to seams.
✓Debris and Leaf Clearing
Removes cottonwood fluff, pine needles, and rooftop debris that collect around HVAC units and drains on flat commercial roofs.
✓Gutter and Scupper Cleaning
Clears internal gutters and exterior scuppers on Spokane commercial buildings to prevent ice dams and spring overflow.
✓Protective Treatment Application
Applies zinc or copper-based treatments that slow moss return for two seasons on Spokane County commercial roofs.
✓Post-Storm Roof Inspection
Checks for wind-driven debris and membrane damage after major wind or hail events that hit the Spokane Valley each spring.
Commercial Roof Cleaning Cost in Spokane, WA
| Service | Typical Range | What Affects It |
|---|---|---|
| Small Commercial Roof Cleaning | $800–$1,600 | Under 5,000 sq ft, single-story access |
| Medium Commercial Roof Cleaning | $1,800–$3,200 | 5,000–15,000 sq ft with multiple HVAC units |
| Protective Treatment Add-On | $0.15–$0.30 per sq ft | Applied after cleaning, extends moss-free period |
| Gutter and Scupper Clearing | $350–$650 | Per building elevation when done with roof cleaning |
Ranges are typical for Spokane, WA and confirmed with an exact written quote before any work starts.
How it works
- 1
Site Walk and Assessment
Technician inspects membrane type, drainage, and growth patterns from the ground and rooftop access points.
- 2
Targeted Cleaning
Low-pressure application of roof-safe solution loosens moss and algae while protecting seams and flashings.
- 3
Rinse and Debris Removal
Material is collected and bagged rather than washed into downspouts or neighboring properties.
- 4
Treatment and Documentation
Protective treatment is applied and photos are provided showing cleaned sections and any noted concerns.
Pricing
Pricing varies by roof size, access, and amount of growth; estimates provided after site visit.