Will moss kill my roof?

Yes, eventually. Moss roots lift the shingle edge and trap water between the shingle and the underlayment — over 5+ years that rots the deck and accelerates granule loss. A 30-year roof becomes a 18-year roof.

Can I just bleach the roof?

Bleach kills the moss but corrodes flashings, kills the lawn below, and leaves white streaks. We use zinc sulfate — same effect, no collateral damage.

How often should moss be treated?

Once every 2–3 years on a tree-shaded roof, or annually if you're surrounded by cedars. A zinc strip at the ridge cuts treatment frequency in half.

Will moss come back after treatment?

Spores will keep arriving. The treatment kills active growth; the zinc strip prevents new growth. Without zinc, expect re-treatment in 3–5 years.

Roof Moss Removal — Why It Damages Your Roof and How to Treat It

What you're dealing with

Moss roots lift shingle edges and trap water against the deck — the #1 reason Lower Mainland roofs die at year 18 instead of year 30. The reason this is such a common issue across the Lower Mainland comes down to two things: our climate (165+ wet days a year in Vancouver, atmospheric river events that drop 60mm overnight, and a freeze/thaw cycle that punishes any roof detail that isn't perfect) and our housing stock (a huge volume of 1970s–2000s shingle and cedar roofs that are now in the back half of their service life). When we tell anyone with mature trees, especially North Shore, Coquitlam, and Maple Ridge homes on north-facing slopes that we see this exact issue on 30–40% of our inspection calls, that isn't a sales pitch — it's the field data. The good news is that the diagnosis is usually straightforward and the fix is usually proportionate to the cause. The bad news is that ignoring the early signs almost always leads to a repair that's 4–10× more expensive than catching it at the right moment. The rest of this guide breaks the problem down into signs, causes, costs, and code — in that order — so you can size up your own situation before any contractor walks your roof. The published price range we see for the work covered on this page is roughly $350 to $1,200. That's a wide range because the variables — roof access, pitch, condition of the deck below, scope of repair vs replacement — change the number a lot. Use this guide to narrow it down before you call.

Warning signs to watch for

Before you ever climb a ladder, you can spot most of these problems from the ground or from inside the house. Look for the following:

1. Green or black mats on north slopes

This is one of the earliest indicators we look for during a free inspection. In our experience, this shows up first on north-facing slopes and at the eaves, then progresses inward as the failure spreads. It's a leading indicator — by the time you see it from the ground, the underlying issue has typically been developing for 6–18 months. We document it with photos during the inspection and use it to triangulate where the actual failure is upstream of the visible symptom. If you spot this on your home, we recommend booking an inspection before the next significant rain event — most of the time we can quote a contained repair instead of a structural rebuild, but that window closes fast in our climate.

2. Raised shingle edges where moss has grown

This is one of the earliest indicators we look for during a free inspection. In our experience, this shows up first on north-facing slopes and at the eaves, then progresses inward as the failure spreads. It's a leading indicator — by the time you see it from the ground, the underlying issue has typically been developing for 6–18 months. We document it with photos during the inspection and use it to triangulate where the actual failure is upstream of the visible symptom. If you spot this on your home, we recommend booking an inspection before the next significant rain event — most of the time we can quote a contained repair instead of a structural rebuild, but that window closes fast in our climate.

3. Granule loss in the moss zone

This is one of the earliest indicators we look for during a free inspection. In our experience, this shows up first on north-facing slopes and at the eaves, then progresses inward as the failure spreads. It's a leading indicator — by the time you see it from the ground, the underlying issue has typically been developing for 6–18 months. We document it with photos during the inspection and use it to triangulate where the actual failure is upstream of the visible symptom. If you spot this on your home, we recommend booking an inspection before the next significant rain event — most of the time we can quote a contained repair instead of a structural rebuild, but that window closes fast in our climate.

4. Staining streaks below the moss patches

This is one of the earliest indicators we look for during a free inspection. In our experience, this shows up first on north-facing slopes and at the eaves, then progresses inward as the failure spreads. It's a leading indicator — by the time you see it from the ground, the underlying issue has typically been developing for 6–18 months. We document it with photos during the inspection and use it to triangulate where the actual failure is upstream of the visible symptom. If you spot this on your home, we recommend booking an inspection before the next significant rain event — most of the time we can quote a contained repair instead of a structural rebuild, but that window closes fast in our climate.

5. Tabs that flap loose in wind

This is one of the earliest indicators we look for during a free inspection. In our experience, this shows up first on north-facing slopes and at the eaves, then progresses inward as the failure spreads. It's a leading indicator — by the time you see it from the ground, the underlying issue has typically been developing for 6–18 months. We document it with photos during the inspection and use it to triangulate where the actual failure is upstream of the visible symptom. If you spot this on your home, we recommend booking an inspection before the next significant rain event — most of the time we can quote a contained repair instead of a structural rebuild, but that window closes fast in our climate.

What's actually causing it

Most homeowners assume the visible symptom is the problem. It almost never is. Water travels — sometimes 4–10 feet across a sheet of underlayment before it shows up as a stain on a ceiling — and what looks like a leak above the dining room is just as often a failed flashing 12 feet uphill. Here are the root causes we identify most often on Lower Mainland inspections:

Cause 1: Overhanging tree canopy

This is one of the most common root causes we identify in the Lower Mainland because of how our climate, our housing stock, and historical installation practices interact. The 1970s–1990s building boom across Burnaby, Surrey, Coquitlam, North Van and Vancouver locked in installation details that don't hold up against today's storms or against current code expectations. When we open up an affected area, this is almost always either present on its own or paired with one of the other causes listed here. The right way to confirm this on your specific home is a 30-minute inspection — we walk the roof (with harness and proper anchors), we walk the attic with a flashlight and a moisture meter, and we report back with photos and a written scope. There's no charge for the inspection and no obligation to book the work.

Cause 2: North-facing slopes with low UV exposure

This is one of the most common root causes we identify in the Lower Mainland because of how our climate, our housing stock, and historical installation practices interact. The 1970s–1990s building boom across Burnaby, Surrey, Coquitlam, North Van and Vancouver locked in installation details that don't hold up against today's storms or against current code expectations. When we open up an affected area, this is almost always either present on its own or paired with one of the other causes listed here. The right way to confirm this on your specific home is a 30-minute inspection — we walk the roof (with harness and proper anchors), we walk the attic with a flashlight and a moisture meter, and we report back with photos and a written scope. There's no charge for the inspection and no obligation to book the work.

Cause 3: Clogged gutters trapping moisture

This is one of the most common root causes we identify in the Lower Mainland because of how our climate, our housing stock, and historical installation practices interact. The 1970s–1990s building boom across Burnaby, Surrey, Coquitlam, North Van and Vancouver locked in installation details that don't hold up against today's storms or against current code expectations. When we open up an affected area, this is almost always either present on its own or paired with one of the other causes listed here. The right way to confirm this on your specific home is a 30-minute inspection — we walk the roof (with harness and proper anchors), we walk the attic with a flashlight and a moisture meter, and we report back with photos and a written scope. There's no charge for the inspection and no obligation to book the work.

Cause 4: Aged shingles that have lost their algae-resistant coating

This is one of the most common root causes we identify in the Lower Mainland because of how our climate, our housing stock, and historical installation practices interact. The 1970s–1990s building boom across Burnaby, Surrey, Coquitlam, North Van and Vancouver locked in installation details that don't hold up against today's storms or against current code expectations. When we open up an affected area, this is almost always either present on its own or paired with one of the other causes listed here. The right way to confirm this on your specific home is a 30-minute inspection — we walk the roof (with harness and proper anchors), we walk the attic with a flashlight and a moisture meter, and we report back with photos and a written scope. There's no charge for the inspection and no obligation to book the work.

Your fix options and what they cost in 2026

These are the published prices we charge for this work in 2026, current as of this article date. They're the same prices we'd quote you on the phone. There's no surge pricing in storm months, no special rate for difficult addresses, and no haggling — what you see here is what lands on the contract. The only line items that vary are pitch (steeper costs more in labour), pitch access, and the actual condition of the substrate once we open it up (which we always quote as a separate unit price up front).

Soft-wash moss treatment — $350–$650

no-pressure spray of zinc sulfate solution, brush out dead moss, rinse — preserves shingle granules. We typically recommend this option when your roof condition matches the description above and the rest of the assembly is in serviceable condition. The job takes between half a day and two days depending on roof access, and we book installs 2–4 weeks out — sooner for emergency leaks. Our published rate includes all materials, all labour, dump fees, the manufacturer warranty, and our 10-year workmanship warranty in writing. There are no trip fees, no fuel surcharges, and no admin fees. If you'd rather see the math behind these numbers, our 2026 Vancouver pricing guide breaks it down by the square — these prices apply uniformly across all 18 cities we serve from West Vancouver to Chilliwack.

Zinc strip install — $250–$450 add-on

metallic zinc strip under the ridge cap leaches over time and prevents regrowth for 10+ years. We typically recommend this option when your roof condition matches the description above and the rest of the assembly is in serviceable condition. The job takes between half a day and two days depending on roof access, and we book installs 2–4 weeks out — sooner for emergency leaks. Our published rate includes all materials, all labour, dump fees, the manufacturer warranty, and our 10-year workmanship warranty in writing. There are no trip fees, no fuel surcharges, and no admin fees. If you'd rather see the math behind these numbers, our 2026 Vancouver pricing guide breaks it down by the square — these prices apply uniformly across all 18 cities we serve from West Vancouver to Chilliwack.

Annual maintenance program — $450/year

two visits a year, gutter clean + spot-treat new moss, inspection report. We typically recommend this option when your roof condition matches the description above and the rest of the assembly is in serviceable condition. The job takes between half a day and two days depending on roof access, and we book installs 2–4 weeks out — sooner for emergency leaks. Our published rate includes all materials, all labour, dump fees, the manufacturer warranty, and our 10-year workmanship warranty in writing. There are no trip fees, no fuel surcharges, and no admin fees. If you'd rather see the math behind these numbers, our 2026 Vancouver pricing guide breaks it down by the square — these prices apply uniformly across all 18 cities we serve from West Vancouver to Chilliwack.

Tree limb pruning — varies by tree

removing the moisture source is the only permanent fix — we coordinate with arborists. We typically recommend this option when your roof condition matches the description above and the rest of the assembly is in serviceable condition. The job takes between half a day and two days depending on roof access, and we book installs 2–4 weeks out — sooner for emergency leaks. Our published rate includes all materials, all labour, dump fees, the manufacturer warranty, and our 10-year workmanship warranty in writing. There are no trip fees, no fuel surcharges, and no admin fees. If you'd rather see the math behind these numbers, our 2026 Vancouver pricing guide breaks it down by the square — these prices apply uniformly across all 18 cities we serve from West Vancouver to Chilliwack.

What BC code requires

The applicable code for this work in the Lower Mainland is There's no code requirement for moss treatment, but most shingle warranties (e.g. IKO, Malarkey) will void coverage if moss damage is clearly the result of deferred maintenance.. The City of Vancouver enforces the Vancouver Building By-law (VBBL) on top of the BCBC, which is stricter on ventilation, flashing, and fire-rating. Other Lower Mainland municipalities (Burnaby, Surrey, Coquitlam, Richmond, North Vancouver, etc.) defer to the BCBC with their own bylaw amendments — most are similar enough that an installer who can pass a Vancouver inspection will pass anywhere in the region. What this means for you as a homeowner: any quote you receive should reference these codes by section number. If a contractor can't tell you which BCBC clause governs the work they're proposing, that's a flag. We're members of the Roofing Contractors Association of BC (RCABC), our crews carry WorkSafeBC coverage and Hot Roofing Insurance certificates where required, and we pull every permit at cost with the fee itemised on the invoice. The City of Vancouver's smoke-alarm declaration on permit close-out is included; we handle the paperwork end to end. Inspection-wise, the local building inspector typically wants to see (1) the underlayment installation before shingles go on, and (2) the completed roof before the permit is closed. We schedule both inspections and meet the inspector on site — homeowners don't need to be present for either.

DIY or call a pro?

Here's our honest take on what you can safely do yourself versus what should always be hired out: Pressure-washing a roof voids the shingle warranty and strips granules. Soft-wash is safe; pressure-wash is not. If you're DIY-ing it, use a garden sprayer with diluted zinc sulfate, never a pressure washer. Beyond the safety question, there's the warranty question. Most shingle and membrane manufacturers (IKO, Malarkey, CertainTeed, Soprema, IKO ArmourGard) require installation by a registered contractor for the full extended warranty to apply. A homeowner repair, even a competent one, voids that. If your roof is under 10 years old and still has manufacturer coverage, it's almost always worth calling in a registered installer to keep the paper trail clean. There's also the insurance angle. If a DIY repair fails and causes interior damage, your home insurance carrier can — and routinely does — deny the claim on grounds of unprofessional work. The cost of a $400 professional repair is dwarfed by the cost of a denied $15,000 mould remediation claim two years later.

How Budget Roofers handles this work

Our model across the Lower Mainland is simple: published square rates, no in-home sales call required, a 60-second online calculator that gives you a real number, and a single licensed estimator who books your install date on the same call. For repair work specifically, we run a 30-minute free inspection (free, no obligation, no upsell), provide a written scope with photos within 24 hours, and book the repair within 2–4 weeks. Emergency leaks get tarped within 24 hours and properly repaired on the next dry-weather window. We're a small, owner-operated crew — not a franchise, not a marketing-led contractor with subbed-out installers. The same crew that comes to inspect your roof is the crew that does the work. We carry $5M general liability, full WorkSafeBC coverage, and Hot Roofing Insurance for any torch-on work. All work comes with a 10-year workmanship warranty in writing on top of the manufacturer's material warranty. If you'd like to see our published rates by city, browse the Lower Mainland cost guides hub — every city from West Vancouver to Chilliwack has its own pricing guide with local code, recycling, and a real case study from a recent install. The published rates apply uniformly across all 18 cities; the city pages exist so you can confirm we work in your municipality and see local-specific code notes.

Next steps

If anything in this guide matches what you're seeing on your home, the next step is a free 30-minute inspection. Use the lead form below or call us at 604-446-3482 — we'll ask 4–5 questions about your roof (age, material, what you're seeing), and either book an inspection or, for some clearcut issues, quote you on the spot. For a real square-rate estimate before we even visit, use the calculator on our home page — enter your roof footprint, pitch, and material and you'll get a published-rate number in under a minute. The estimator who calls you back will reference that number; it doesn't change unless your roof condition does. We answer the phone Monday to Saturday, 8 AM to 6 PM. After-hours emergency leaks get a callback within 60 minutes. Same crew that quotes is the crew that installs — we don't sub the work out. Read the next guide on Gutter Repair & Replacement Cost in BC or browse the full blog index.