A practical, May-timing checklist for Calgary homeowners and property managers, written by a Red Seal roofing team that has worked the hail corridor for 25 years.
Calgary’s hail season runs roughly June 1 through the end of August, with the meanest supercells usually firing between mid-June and mid-July. The Insurance Bureau of Canada has flagged Calgary as Canada’s hail capital for a decade running, and the city sits squarely under the most active severe-weather corridor on the prairies. The numbers move every year, but the pattern does not: if you own a roof here, May is the last quiet window to get ahead of the damage.
A pre-season inspection is not a sales call dressed up. Done properly, it is a 45-minute walk of every slope, every flashing, every penetration, and every drainage point on the roof, with a written report and dated photos. The point is to fix the small things in May that turn into five-figure claims in July. This checklist is the one our crews run on residential and small commercial roofs across the city before each hail season.
Why May is the right month, not April or June
Calgary snowpack typically clears off pitched roofs by late April, and overnight lows are still cold enough that the asphalt mat has not yet softened. That combination matters. A roof inspected in early May is dry, accessible, and stable to walk. By the second week of June, afternoon temperatures regularly hit the high 20s and asphalt shingles soften enough that a careless boot prints the surface and shortens the roof’s life.
April is too early for two reasons. Late spring snowfalls still hit Calgary through the first week of May in roughly one year out of three, and any inspection completed before the last freeze can miss damage that surfaces in the final thaw cycle. June is too late because storm activity has already started, supply chains tighten as claims open, and crews are booked solid on emergency tarp work.
The practical window is the first three weeks of May. Schedule the inspection on a dry day with overnight lows above zero and afternoon highs below 20°C and you get the cleanest read.
What a proper pre-season inspection actually covers
An inspection that fits on a single page is too short. A pre-season report should document the condition of every component the hail and wind season will load. The minimum scope:
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Shingle field condition — granule loss, curling, cupping, blistering, and any soft spots flagged on each slope with chalk and photographed.
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Ridge and hip caps — these get the most UV and the most wind, and they fail first.
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Step flashings at wall transitions, kick-out flashings at eave terminations, and counter-flashing reglets at chimneys.
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Pipe boot collars, B-vent storm collars, and any rubber gasket on a roof penetration older than seven years.
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Skylight curbs, weep channels, and the shingle seal at the top corners.
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Eavestroughs, downspouts, splash blocks, and the soil grade where the downspout discharges.
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Soffit intake vents — count them, check for paint-overs, confirm the screening behind each one is open.
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Roof exhaust — gable vents, ridge vents, or box vents — and confirm the ratio against intake.
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Attic from below if access exists: insulation depth, frost-stain patterns on the deck, and any daylight visible at penetrations.
Items one through five concern the roof’s watertight integrity. Items six through nine concern the ventilation and drainage system that keeps the watertight layer working. Skip the second half and a clean roof still rots from the inside in five years.
The five fixes worth making in May
A pre-season inspection that does not lead to small repairs is mostly theatre. Five fixes consistently pay back well above their cost when completed before the first June storm.
Re-sealing exposed fasteners. Every nail head that has lost its sealant cap is a future leak. A tube of tripolymer sealant and an hour on the roof closes 30 to 50 fastener heads on a typical Calgary bungalow.
Replacing pipe boot collars at year seven or older. The rubber gasket around plumbing stacks is the single most common leak point in Calgary. A retrofit collar with a fresh EPDM ring runs about $40 in materials and 20 minutes of labour per stack.
Cleaning eavestroughs and confirming downspout flow. A clogged trough during a hail-and-rain event overflows and backwashes water under the starter course. Flush the system in May and the storm-flow path stays predictable.
Re-bedding ridge cap shingles that have been lifted. A single ridge cap missing its seal can take 10 caps with it in a 90 km/h Chinook. Caulk and re-bond before the wind season.
Resetting loose flashing nails at chimneys and wall transitions. These shift slightly with every freeze-thaw cycle and create a slow-water-entry path that doesn’t show in the attic until November.
Documenting what’s already there
Pre-season inspection photos serve a second purpose that most homeowners do not think about until July: they become the baseline against which post-storm damage is measured. A roof photographed in May with no granule loss and clean flashings produces a much stronger claim than a roof photographed for the first time after the hail.
Insurance adjusters in Alberta routinely deny portions of claims by citing pre-existing wear. The defence is a dated, time-stamped, GPS-tagged inspection photo set showing the roof’s condition before the loss. Most modern phones embed all three automatically — leave the metadata setting on and store the photos in a labelled folder.
On commercial buildings, the same baseline applies to the membrane, the parapet flashing, the rooftop unit curbs, and any pitch-pocket sealant. A property manager who can hand the adjuster a folder of May 1 photos shortens the claim cycle by weeks.
Hail-rated upgrades to consider before the storm
If the existing roof is more than 15 years old and the inspection turns up multiple deficiencies, May is the right time to discuss upgrade options rather than a patch. Three upgrades meaningfully reduce claim frequency in Calgary’s hail corridor.
Impact-resistant shingles rated UL 2218 Class 4 — the top of the impact scale — qualify for premium discounts with most Alberta home insurers and have measurably lower granule-loss rates after sub-severe storms. The price premium over a standard architectural shingle is roughly 15 to 25 percent.
Synthetic underlayment in place of 15-pound felt. Synthetic stays intact when wind lifts shingles and resists tearing during impact events. The material upgrade is modest and the labour cost is identical.
Rubber polymer roofing such as Euroshield, made from recycled tires, carries a Class 4 impact rating and a 50-year warranty. It costs more than asphalt up front but eliminates the hail-claim cycle entirely on most properties. A Calgary roof installer authorized for Class 4 systems can walk through which option fits the building.
Red flags that mean don’t wait
A pre-season inspection sometimes turns up findings that are not pre-season problems — they are right-now problems. Stop the checklist and book replacement work immediately if any of the following show up:
Daylight visible through the deck from inside the attic. The roof is no longer watertight, and the first heavy rain will find the wet bay.
Active drip stains on top-floor ceilings that have not been investigated. Slow leaks accelerate fast once the hail season starts.
More than 10 percent of shingles showing granule-bare patches the size of a loonie or larger. The asphalt mat is already cooking and a hail event finishes it.
Two or more adjacent missing or torn shingles on the same slope. The exposure compounds with the next wind event.
Visible sag along any roof plane. The deck or structural elements may be compromised and need engineering review before any further work.
Spend an hour in May to save a season
A pre-season roof inspection is the single highest-return hour of attention a Calgary roof gets all year. It costs nothing if booked with a Calgary roofing company that offers free pre-season inspections, and it routinely catches issues that would otherwise become a denied claim component or a $15,000 emergency repair in July.
The first three weeks of May are the right window. Walk every slope, document every component, fix the five quick items, and store the photos somewhere you can find them after a storm. Hail will arrive on its own schedule. The only variable you control is what condition the roof is in when it hits.
About the author — this article was contributed by Superior Roofing Ltd., a Calgary-based contractor with 25+ years of hail-corridor experience. The team includes Red Seal Journeymen and HAAG Certified inspectors, carries $10 million in liability coverage, and runs free pre-season inspections across the city through May each year.