How Moss and Algae Shorten Roof Lifespan in Victoria’s Coastal Climate

Roofs in Victoria and across Vancouver Island face challenges that homeowners in other parts of Canada rarely experience. The combination of moisture, shade, and mild temperatures creates the perfect environment for biological growth on roofing systems.

Why Moss Loves Vancouver Island Roofs

Moss and algae thrive where moisture lingers. On Vancouver Island:

• Frequent rainfall keeps shingles damp

• Tree cover limits sun exposure

• Mild winters prevent die-off

Once moss establishes itself, it begins lifting shingles, allowing water to penetrate underneath. This leads to:

• Freeze-thaw damage

• Rotting roof deck edges

• Accelerated shingle breakdown

The Granule Loss Problem

Asphalt shingles rely on granules for:

• UV protection

• Fire resistance

• Weather durability

When moss is scraped or pressure washed away, granules are often removed with it. Multiple roofing studies have shown that even a single aggressive cleaning can remove years of remaining shingle life.

This is why many roofs in Victoria appear visually “clean” after demossing, but fail prematurely within a few years.

Why Roof Treatments Outperform Roof Cleaning

Modern roof preservation focuses on biological control, not surface destruction.

GoNano roof treatments work by:

• Penetrating microscopic shingle pores

• Neutralizing moss, algae, and lichen

• Creating an inhospitable surface for regrowth

• Preserving granules and shingle structure

For homeowners on Vancouver Island, this means fewer cleanings, lower long-term costs, and a longer-lasting roof.

External Resources:

1. Asphalt Roofing Manufacturers Association (ARMA)

Link: https://www.asphaltroofing.org/ 

About it:The Asphalt Roofing Manufacturers Association (ARMA) is a trade association representing asphalt roofing manufacturers across North America. It promotes quality industry standards, research, and education on asphalt roofing products such as shingles and low-slope membranes. ARMA provides technical resources, best-practice guides, and info for both professionals and the public.

2. National Research Council of Canada (NRC)

Link: https://nrc.canada.ca/en 

About it:The National Research Council Canada (NRC) is Canada’s primary federal research organization dedicated to science and technology across many fields, including building materials, construction science, and climate-related research. NRC undertakes research on building longevity, material performance, and climate resilience, and offers tools and publications that can support understanding of roof durability under Canadian climate conditions.

3. Environment Canada Precipitation & Climate Data

Historical Climate Data & Station Search: https://climate.weather.gc.ca/ 

Engineering Climate Datasets (rainfall intensity, etc.): https://climate.weather.gc.ca/prods_servs/engineering_e.html 

About it:These official Government of Canada resources provide climate and weather data, including precipitation, temperature, and averages for locations across Canada. You can search by city (such as Victoria, British Columbia) to view historic precipitation totals, monthly averages, extremes, and engineering climate datasets used for planning and design purposes.

Optional: NRC Roof-Related Tool (Climate-RCI)

Link: https://nrc.canada.ca/en/research-development/products-services/software-applications/climate-rci 

About it: Climate-RCI is a National Research Council web application that estimates climate severity and roof performance requirements (current and future), using Environment Canada climate data. This tool is useful for engineers and architects assessing roof design under Canadian climate conditions.