Moss and maintenance
How do you keep moss from costing you a new roof?
Nanaimo Roofers removes moss and maintains asphalt and metal roofs across Nanaimo, Cedar, Lantzville and Gabriola Island. Roofs here take 1,000 mm of rain a year under heavy tree cover, so we keep an eye on moss and debris for you.
Moss holds water against your shingles and wicks it uphill under the tabs.
What moss actually does
As a moss mat thickens at a course edge, it lifts the shingle tab above it, and wind-driven rain gets under the course. We reset a lifted tab as part of every treatment visit, so the course seals back down before the next storm. On a north face under fir cover, a roof left with moss on it tends to reach the low end of its twenty-five to thirty year range rather than the high end.
How it comes off
We treat first, then remove gently, working down the slope so nothing is driven under a course. Asphalt shingles are never pressure-washed: the granules are the wear surface, and pressure strips them off the roof. Metal panels tolerate more, but the fasteners and gaskets on a profiled roof do not.
Keeping it off
A strip of zinc or copper at the ridge releases enough metal in runoff to slow regrowth down the slope below it. We cut back branches overhanging the roof so the surface dries between rains, and we clear gutters and valleys so debris does not hold moisture at the edge. Most of what we do on a maintenance visit is clearing debris and vegetation off the roof.
Why spring and fall
We look at a roof twice a year, in spring and in fall, and a visit on that schedule usually takes us under an hour. Stay on it and we generally end up repairing your roof rather than replacing it.
Moss on a metal roof
Moss will not root in a standing seam panel, but it will sit in a valley, pack behind a snow guard and block a downspout. On a metal roof we check drainage, fasteners and the sealant at penetrations.
What's included
Roof moss treatment and removal
Zinc and copper ridge strip installation
Gutter, valley and debris clearing
Spring and fall roof inspection
People also ask
Can moss just be scraped off?
Dry scraping takes granules with it and pulls at the tab edges it is meant to free. Treating first and removing gently afterwards leaves the wear surface where it belongs.
Does a moss-covered roof always need replacing?
Not on its own. It depends on what is under the moss. We check whether the tabs have been lifted long enough for water to reach the underlay, and whether the deck has gone soft anywhere.
How long do ridge strips last?
A strip works by shedding metal into the runoff, so it is consumed slowly and its effect reaches only the slope below it. A roof with dormers or several planes needs more than one run.
Should gutters be done at the same time?
It is the same access and the same debris. We clear your gutters and valleys on the same visit, since that is where water backs up and sits longest.
Keep exploring
- What a new roof costsInstalled price by material, and what moves it on a given roof.
- Permits by communityWho issues the permit for an address, and what each authority asks for.
- Where the work isThe communities covered across the Regional District of Nanaimo.
- Roof repair and leak tracingFlashing, valleys, penetrations and laps. Finding where water enters a roof, which is almost never directly above the stain on the ceiling.
- Metal roof systemsStanding seam and profiled metal from a slope of 1 in 4 with no upper limit, detailed for a 2.1 kPa ground snow load and a 0.50 kPa design wind.
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