Should trees be trimmed back from my Calgary roof?

Yes, keeping trees trimmed back from your roof is one of the more cost-effective things a Calgary homeowner can do to extend the life of their shingles and avoid repairs that run anywhere from $300 to over $3,000 depending on the damage.

Why It Matters More in Calgary

Overhanging branches do several things that shorten a roof's life. They scrape and abrade shingles during wind events, and Calgary gets plenty of those: chinooks, cold fronts and severe thunderstorms all move branches hard against a roof surface. Leaves and needles pile up in valleys and eavestroughs, trapping moisture against the shingles and accelerating granule loss. Shade from dense canopy keeps the roof surface damp longer after rain or snow, which encourages moss and algae growth and softens the wood decking underneath over time.

The freeze-thaw cycle makes this worse here than in most Canadian cities. Calgary averages roughly 128 freeze-thaw cycles a year. Any debris holding moisture against a shingle or in a valley goes through that cycle repeatedly, working water under the shingle edges and into the decking. Ice dams form more easily where drainage is blocked by leaf buildup in the eavestrough.

Then there is hail. Calgary sits in what the City of Calgary calls "hail alley," the most hail-prone part of Canada. A branch resting on or close to the roof during a hailstorm becomes a secondary impact point, concentrating force on the shingles beneath it and making damage worse than it would be on an open section of roof.

A branch that falls onto the roof during a storm is a different problem entirely. Impact damage to decking or structural members means calling your insurer before touching anything, documenting everything with photos from the ground, and getting a roofer to assess the scope in writing before repairs start.

Practical trimming guidance

A general rule among arborists is to keep branches at least two to three metres clear of the roof surface, and further if the tree is a heavy shedder like a spruce or a cottonwood. That clearance gives branches room to move in wind without contacting the shingles. Trimming is typically done by a certified arborist rather than a roofer; it is outside the scope of a roofing contract.

From a roofing standpoint, the inspection checklist after any trimming work should include: clearing the eavestroughs and downspouts of debris, checking the valleys for accumulated material, and looking at the attic from inside for any water staining or daylight that might point to existing damage. You can do the eavestrough check safely from a properly footed ladder without going onto the roof surface itself. Never walk a steep, wet or icy roof.

If the trimming reveals shingles that are already cracked, cupped or missing granules, that is worth a roofer's eye before hail season (roughly June through August) rather than after. A basic inspection runs about $150 to $400, though many roofers will include one at no charge when they are quoting a repair or replacement.

For routine maintenance questions the roofer is your first call; for storm damage with a branch impact, contact your insurer first so the damage is documented before any repair work begins.