What Causes Roof Stains
Your home may have a beautiful exterior, but stains on your roof can be an eyesore. What’s more, you might have concerns as a homeowner about what is causing the stains. Can the discolouration be removed or prevented? Do you need professional help?
There are a few things that could be causing the unsightly marks on your roof. Figuring out which type of staining you have, as well as the overall condition of your roof will help you plan the best course of action.
Black Streaks Probably Mean Algae
The most common cause of roof staining is a form of algae. These tiny growths cause the unsightly black streaks that are found on roofs across the country. Although warmer costal climates are more hospitable to algae growth, it’s still an issues throughout most of B.C. because of our hotter and humid summers. Algae feed on the limestone in asphalt shingles and spread over a roof, causing the signature black streaking. By the time you notice discolouration occuring on your roof, the algae have probably been growing for some time.
The good news is that these algae are largely harmless and easy to treat. An algae problem doesnt mean your roof needs replacing. However, if allowed to grow over an extended period of time, algae can start to degrade the UV protection on shingles or turn into a larger problem, so it’s best to take care of the problem sooner rather than later.
Preventing Algae Growth
Algae love moist environments which is why black streaks appear most often on northern roof exposures where there is less sunlight to evaporate lingering moisture. Algae can also be a sign that your roof may have moisture retention issues.
It’s tough to prevent algae but keeping your roof dry can help. Trim branches that block sunlight, clear any debris which traps moisture can can cause discolouration, make sure your gutters are clear and draining well. Simple maintenance is the best way to keep algae at bay.
Treating Algae Stains
Getting rid of the black stains on your roof is fairly easy. You can even do it yourself with some basic materials, but it’s always best to have a roofing professional perform the work to ensure you don’t void your shingle manufacturer’s warranty by doing it yourself.
spray-on algaecide which is widely available in big box stores is a common treatment method. Wait for a dry, overcast day which will give your cleaning agent the maximum time to go to work without washing away or drying up. Cover any landscaping under your gutter line and remove any furniture and lawn decorations near the perimeter of your home. Put on protective gear and non-slip shoes. Avoid using a power washer which can damage your shingles. Instead, use a regular, pump-style garden sprayer and use it to gently spray down the roof with the solution. After about 20 minutes, rinse with regular water from a hose.
You may not immediately notice a difference in the staining, but don’t panic. It can take up to a month before there is a visible reduction in algae growth.
When Algae Turns to Lichen, call the Pros
The real danger of algae growth is when it combines with airborne fungus particles to create lichen. Splotchy growths which can be blue-green, grey or a variety of other colours. Lichen grows roots and feeds off your shingles which can cause a lot of damage. Once lichen is on a roof, it can be very difficult to remove. If you notice lichen growing on your roof, contact a roofing professional as soon as possible to evaluate your options.
When Staining Means It’s Time For a Roof Replacement
Eventually, all roofs need to be replaced, whether due to age or damage. Unsure about whether it’s time to replace your roof or not? Contact us today for a free, no obligation consultation and estimate. If you’re due for a replacement, our team would be happy to assess your roof and provide recommendations.
In Awe Roofing Limited is an Award-Winning, family owned and operated Vancouver Roofing Contractor with over 17 years of roofing experience. We serve the entire Lower Mainland area, from Whistler to Chilliwack, employing a team of professional staff members. Our team has won numerous awards including Best of Homestars for the last five years, and Three Best Rated six years in a row. Learn more
