Roof-Cleaning 101: Answering the Why, When, and How of Cleaning Shingles | Great Canadian Roofing & Siding

When’s the last time you cleaned your roof? If you’re like the majority of us you either don’t remember, or worse, you have never cleaned your roof. Ouch. It’s time to remedy the situation so your expensive could-be 30-year roof doesn’t become a has-been 15-year roof.

Why Roof Cleaning Matters
Over time, dirt, mould, and algae tend to accumulate on your roof (particularly in a humid climate). If you want your roof to last a long time, it’s important to clean your shingles or tiles. A side benefit? Your home’s curb appeal improves dramatically.

Why Power Washing is NOT the Answer
We’ve all heard that power washing a roof is the only way to remove those stubborn algae stains, moss, and dirt. WRONG. Here’s why:

  • Power washing strips away the protective granular coating from your roofing, shortening its life.
  • Power washing risks causing loft-space flooding and many thousands of dollars in damages.

Bottom line: Just don’t do it!

When to Clean Your Roof
The best time of year to clean a roof is during summer, on a day when the optimum temperature is between 15 and 25° C. Too hot, and chemicals may evaporate too soon; too cold, and the roof becomes slick and dangerous.

How to Clean Your Roof
There’s no “one” method for roof cleaning; however, here are a few tips for the Do-it-Yourselfer:

  1. Wear skidproof shoes, safety goggles, and a harness! Better safe than severely injured.
  2. Cover your plants with plastic sheeting.
  3. Consider using anti-algae solution in a backpack sprayer; it extends your reach.
  4. For stubborn dirt and algae, you may need to scrub. Be careful! If you must use some pressure rinsing, be sure it’s below 400 psi. It’s still better to avoid it altogether.
  5. The best sprays may be left on until the next time it rains (but leave protection on your plants until then).

Don’t want to take any risks yourself? Let a Great Canadian professional do the job.