Green, grey or black streaks on siding and fences are common on homes around Chestermere, especially on shaded walls and surfaces near the water. It’s usually mildew or algae, and it matters more than it looks, particularly if you’re planning to paint.
Why it grows here
Mildew and algae need moisture, shade and something to feed on, such as dust and pollen. Homes near the lake have more humidity in summer, and shaded north-facing walls, areas behind shrubs and spots under decks stay damp longer. Vinyl siding, stucco, wood and even painted surfaces can all be affected.
Why you shouldn’t paint over it
Paint doesn’t kill mildew. If you paint over it, it keeps growing underneath and can show through the new finish within months. It also stops the new paint from bonding properly, which leads to peeling. Every exterior job we do starts with making sure the surface is clean.
How we clean it safely
- Apply a cleaning solution suited to the surface to kill mildew and algae
- Wash at the right pressure for the material, since too much pressure can damage wood, force water behind vinyl or etch stucco
- Rinse thoroughly and protect nearby plants and landscaping
- Let everything dry fully before any primer or paint goes on
For wood, we follow up with a stain or paint that includes mildew-resistant additives.
Stopping it from coming back
- Trim back plants and shrubs so walls get more air and sun
- Keep gutters and downspouts clear so water drains away from the house
- Rinse off dust and pollen once a year
- Choose paints and stains with mildew-resistant properties
Get a free estimate
We power wash and paint homes across Chestermere, and we’ll tell you honestly whether your siding just needs a clean or is ready for a new coat. See our Chestermere painting services or call 403-891-4138.