Moss Removal and Roof Cleaning

What moss actually does to a roof

A moss cushion holds water on the roof surface long after the rain has stopped. Asphalt shingles are built to shed water in hours, not to sit damp for weeks, and constant moisture lifts the granules that protect the asphalt underneath from the sun.

Worse, moss grows sideways. It works its roots under the shingle above and lifts the edge, and once an edge is lifted, wind gets under it and water runs where the roof was never designed to carry it. That is the damage that costs money, and it happens out of sight at the laps.

If you want the biology, the climate numbers and the full prevention rundown, we wrote it all out here: the complete moss and algae guide. This page is the short version and what we charge for.

How we take it off

Soft wash. A moss killing solution goes on at low pressure, it is left to work, and the dead moss is rinsed gently or simply left to weather off over the following weeks. It is slower than scrubbing and it is the only method that does not cost you shingle life.

• We do not pressure wash a shingle roof. Ever. High pressure water strips the granules off asphalt and takes years off the roof in an afternoon. If a company offers to pressure wash your shingles, that is the end of the conversation.
• We do not scrape it bare. A wire brush or a scraper takes granules with the moss. Light manual work on heavy clumps, yes. Scouring the roof, no.
• We work off the roof where we can. Walking a wet mossy roof damages shingles and is how people fall. Moss is slick as ice when it is soaked.
• Valleys, gutters and downpipes get cleared of what comes down, because dead moss that washes into a valley and sits there has just moved the problem.

When a cleaning is money you will not get back

This is the part a cleaning outfit will not tell you. Moss is often the symptom rather than the problem. If the shingles underneath have already lost their granules, gone brittle, or are cupping at the edges, washing them does not restore anything. You get a clean roof that is just as finished as it was, minus the cost of the wash.

So we get on it and look first, and we will say plainly which of the two you have. A roof with ten years left and a moss problem is absolutely worth cleaning. A roof with two years left is worth planning to replace, and we would rather tell you that than take the cleaning money and come back for the real job later.

If it turns out to be the second one, the honest numbers for a roof replacement are published on the site rather than saved for the doorstep.

Stopping it coming back

Cleaning a roof in this climate without doing anything else means doing it again. Zinc strips are fitted at the ridge, and every time it rains a trace of zinc washes down the slope and makes the surface hostile to moss and algae. One installation, no power, nothing to maintain.

We fit them as standard on a re roof and we fit them on their own to a roof that is otherwise fine. Copper does the same job and lasts longer for more money. Neither will strip moss that is already established, so the order matters: clean first, then protect.

Trees are the other half of it. Moss needs shade and damp, so a branch cut back off the north slope does more than any product. We will point out which ones, though cutting them is an arborist's job rather than ours.

What this looks like in the valley

These are real roofs we have been on, photographed before anything was done to them. This is what three to five years of a Fraser Valley north slope looks like.

There are more in the job photo gallery, including the tear offs where the moss had been left long enough to rot the sheathing underneath.

Who is on your roof

Kory and Johnny Peters are brothers, Red Seal Journeyman Boilermakers and members of Local 280, and they are the ones who turn up. Fraser Roofing Ltd. is registered and in good standing with WorkSafeBC, account 201893485, and carries $2,000,000 commercial general liability placed through HUB International.

That matters more on a cleaning than people expect. A wet mossy roof is one of the most slippery surfaces in the trade, and an uninsured person falling off your house becomes your problem. Ask whoever quotes you for a WorkSafeBC clearance letter. We will hand ours over without being asked.

One thing we do not do is gutters. We clear what comes off the roof during the work, but gutter replacement is not ours. We work with Gutters Canada, (604) 362-3488.

What it costs

It depends on the pitch, the height, how much moss there is and whether the roof has anything left worth protecting, so a figure over the phone would be a guess dressed up as a quote. The inspection is free, including the version where we tell you not to bother.

Send us the address, or a photo of the worst slope taken from the ground, and you will get a straight answer about whether this is a cleaning job or a replacement conversation. We start at 06:00 and we cover Chilliwack, Sardis, Cultus Lake, Rosedale, Agassiz, Harrison Hot Springs, Hope, Yale, Mission and Abbotsford.