Moss loves the conditions York Region dishes out: long, wet springs, humid air from Lake Ontario and Lake Simcoe, and mature tree canopies that keep roof shingles in shade for most of the day. Neighbourhoods like Cornell, Berczy Village, and Historic Unionville are full of established lots with big trees, which makes them prime spots for moss growth.
Our team at Edmunds Home Improvements has been working on roofs across Markham and the GTA for over 30 years. We see moss on roofs regularly. This guide is for Markham homeowners concerned with encroaching moss on their roof. Roof moss removal is important because moss can damage your roof, shorten its lifespan, and lead to costly repairs if left untreated.
We’ll cover why moss grows, how to remove moss from your roof, what the process costs, and how to stop it from coming back. If you need hands-on help, our roof repair services in Markham are a good place to start.
Why Moss Grows on Roofs in Markham
Moss is a small, green plant that thrives in shaded, moist areas, including roofs. It spreads by spores that travel on wind and rain. When those spores land on a shaded, damp surface, they take hold and start to grow. You may also notice algae or lichen on your roof alongside moss. All three organisms thrive in similar conditions, but moss causes the most damage because of how much water it holds.
North-facing roof areas are the most common trouble spots because they get the least sun exposure. Homes surrounded by tall trees have it worse because the canopy blocks sunlight and drops organic debris onto shingles, giving moss something to feed on.
Ontario’s freeze-thaw cycling plays a role too. During late fall and early spring, temperatures in York Region swing above and below zero repeatedly. This keeps moisture locked against asphalt shingles for weeks. Unlike drier climates in Alberta or BC’s interior, Markham’s air carries steady humidity from the Great Lakes. That combination of shade, moisture, and cool temperatures is exactly what moss needs to thrive.
Why Roof Moss Removal Matters
Moss acts like a sponge, holding moisture directly against your shingles. That constant dampness accelerates the breakdown of roofing materials. Over time, moss can shorten your roof’s lifespan by up to 30%.
As moss grows thicker, it works its way under shingle edges and lifts them. Once shingles are lifted, water seeps into the roof’s structure, and in severe neglected cases that damage can escalate within a few months. That leads to wood rot, mould growth in your attic, and leaks that can cost thousands to fix.
A moss covered roof also clogs gutters and downspouts. Dead moss washes into your eavestrough system and blocks drainage. The Edmunds team sees this damage on Markham homes every season. Left untreated, a simple cleaning job turns into a costly roof replacement.
How to Remove Moss From Your Roof Safely
Before you start any roof moss removal work, consider safety.
Working on a roof is dangerous. Wear non-slip shoes, use a sturdy extension ladder, and consider a safety harness if your roof is steep. Fall protection is not optional. If you are not comfortable on a ladder or at heights, hire a professional.
Pick a dry, overcast day for the removal process. Never work on a wet roof.
Step 1: Clear Loose Moss With a Soft-Bristled Brush
Start at the top of the roof and work downward. Use a soft-bristled brush or a stiff push broom to gently sweep loose moss off the shingles. Always brush in the direction of the shingle overlap so you do not lift or damage them.
A leaf blower can also help clear loose moss and debris before you apply any treatment. The goal at this stage is to remove moss in bulk with gentle strokes, not to scrub the roof clean. Using a soft-bristled brush prevents damage to the protective granules on your shingles.
Step 2: Apply a Moss Treatment
There are two main types of roof moss treatment: liquid and dry powder. Liquid moss killers attach to a garden hose and spray onto the roof from the ridge down. They cover the surface more evenly and are easier to apply when you want to remove moss over a large area. Dry powder is cheaper but harder to spread evenly. It needs light rain to activate and wash the powder down the roof.
Spray or sprinkle from the peak downward so the solution does not push up under your shingles. Let the treatment sit for weeks. Moss removal is not instant, and it can take months for moss to die completely. Moss can also lie dormant during dry weather and come back when rain returns, so patience is part of the process.
Step 3: Remove Dead Moss and Rinse
Once the moss has turned brown or white, it is dead and ready to be removed. Do not skip this step. Dead moss still holds moisture and can clog your gutters if left in place.
Use the same soft-bristled brush to scrape the dead moss away, working from the eave line upward. Rinse the roof with a garden hose on a normal setting, then clean your gutters. Getting rid of all the dead material is just as important as the treatment.
What Is the Fastest Way to Remove Moss From a Roof?
The fastest way to remove roof moss is to hire a pro who can pre-treat the moss, physically scrape it, and apply a preventative coating in one visit. A professional crew can handle a standard Markham home in a single day.
For DIY, the fastest approach is to apply a liquid moss killer about a week before physical removal. Dead, dried moss is much easier to dislodge than living moss. Trying to scrape off green, living moss is labor intensive and increases the risk of damaging your shingles.
DIY Moss Removal Methods for Homeowners
If you are tackling moss removal yourself, there are a few common approaches.
Homemade Solutions
White vinegar diluted in water (about 1.5 to 3.5 cups per two gallons) is a popular homemade moss killer. You can spray it onto the moss with a pump sprayer and let it sit for 20 to 45 minutes before scrubbing and rinsing. Be careful with runoff near plants and gardens.
Dish soap diluted in water works for light moss but can leave a film on roofing materials. Laundry detergent powder sprinkled along the ridge before rain is another old trick. These homemade cleaning solutions work for light moss, but heavy infestations usually need a commercial product.
Eco Friendly Moss Removal Options
Some commercial moss killers contain zinc compounds that can harm aquatic life and plants if they run off into storm drains. If your home is near a creek or wetland area, this matters.
Sodium diacetate is an eco friendly alternative to zinc-based treatments. It breaks down safely in the environment. Oxygen bleach (sodium percarbonate) is another option that is less harmful to plants than chlorine bleach. Both work effectively for light to moderate moss on a shingle roof.
Why You Should Never Use a Pressure Washer on Your Roof
A pressure washer will strip the protective granules off your roof shingles. Those granules shield the shingle from UV damage, so losing them shortens your roof life. High-pressure water can also force moisture under shingles, causing leaks that may not show up for months.
Using a power washer on your roof can also void your shingle manufacturer’s warranty. Soft washing with low-pressure water and a roof cleaning solution is the safe alternative. This is the most common mistake the Edmunds team sees. If someone recommends pressure washing your roof, get a second opinion.
What Is the Best Time of Year to Kill Roof Moss?
The best time to apply a moss killer in Ontario is late fall (October to November) or early spring (March to April), when moss is actively growing and rainfall helps activate the treatment. Markham’s fall season is a natural window for roof moss treatment.
The best time to physically remove roof moss is mid-summer, when it is dry and brittle. Our July and August dry stretches are ideal for scraping. Treating in fall and removing in early summer gives you the best results in this climate.
How to Prevent Moss Growth on Your Roof
Prevention is cheaper than repeated removal. These steps reduce the risk of future moss growth and extend your roof’s lifespan.
Trim Overhanging Trees
Cutting back overhanging tree branches is one of the best things you can do. Less shade means more sunlight hits your roof and helps it dry faster. A drier roof is less hospitable to moss.
Keep Your Gutters Clean
Clogged eavestroughs trap moisture against your roofline, which feeds moss growth. Clean them twice a year, in spring and fall. Gutter guards are a long-term option that keeps water flowing freely.
Install Zinc or Copper Strips
Zinc or copper strips installed just below the roof ridge are a popular way to prevent regrowth. Rainwater picks up tiny metal particles and carries them down the roof surface, creating conditions where moss cannot grow. The strips need replacing every five years or so, but they are a low-cost option between professional cleanings.
Schedule Annual Roof Inspections
Catching a moss problem early makes it easier and cheaper to remove moss. An annual roof inspection can spot growth before it spreads. Edmunds offers free inspection services for Markham homeowners.
How Much Does It Cost to Have Moss Removed From a Roof?
Professional roof moss removal typically costs between $450 and $750 in the GTA, depending on the size of your roof and the severity of the moss. Light infestations on a smaller roof will be at the lower end. Heavy moss on a large or steep roof with difficult access will cost more. Add-on prevention treatments can increase the initial cost but save you from paying for cleaning services again in a year or two.
For comparison, a full roof replacement in Markham runs from $5,500 to $18,000. Spending a few hundred dollars on roof moss removal and cleaning is a fraction of that cost, and it is highly recommended before problems get worse. Edmunds offers competitive pricing for all our roof cleaning services in Markham.
Is It Worth Having Moss Removed From a Roof?
Yes, moss removal services are worth the cost. Untreated moss can shorten your roof’s lifespan by up to 30%, which means you could face a premature roof replacement costing thousands of dollars before you should need one.
The math is straightforward. Moss removal and cleaning services cost $450 to $750. A new roof costs $5,500 to $18,000 or more. Investing in regular roof moss removal effectively protects your roof and avoids costly repairs down the road.
When to Call a Professional for Roof Moss Removal
DIY moss removal works for light infestations on low-slope roofs where you can work safely. But if your roof is steep or hard to access, professional roof moss removal is the better choice. If you have treated your roof and the moss keeps coming back, a professional cleaning service can apply commercial-grade products and soft washing techniques that last longer.
At Edmunds, our team provides roof cleaning services across Markham every week. We know which roofing materials need special care. If you are not sure whether to repair or replace your roof, a professional inspection can help you decide.
Get Your Roof Checked by Edmunds Home Improvements
If you have noticed moss on your roof, or if it has been a while since your last inspection, give us a call. The team at Edmunds Home Improvements offers free roof inspections and cleaning services for homeowners in Markham and across York Region. We can assess moss damage, recommend treatment, and provide a quote.
Reach us at 905-472-0276 or visit our showroom at 3400 14th Ave, Unit 28, Markham. You can also head to our contact page to get in touch. We are happy to take a look and give you an honest opinion.
Steve Gibson
President & CEO, Edmunds Home Improvements
Steve Gibson has over 35 years of hands-on experience in home renovation across
Markham and the Greater Toronto Area. As President and CEO of Edmunds Home
Improvements — a company serving the community since 1947 — Steve specializes in
roofing installation and repair, siding, window replacement and installation, and
door installation. A longtime local resident, he took ownership of Edmunds in 1989
and has built the company into one of the GTA’s most trusted exterior renovation
contractors. Edmunds is fully insured (WSIB and $5 million public liability) and
is a BBB Accredited Business and ENERGY STAR partner.
