How Often Should a Commercial Roof Be Inspected in Winnipeg?

Why spring and fall matter in Winnipeg

Every source we checked recommends inspections at least twice a year: the Canadian Roofing Contractors Association (CRCA), the U.S. National Roofing Contractors Association (NRCA), the insurer FM Global, and the membrane makers Carlisle and Johns Manville. Most of them name spring and fall. In a Winnipeg climate, each visit has its own job.

• Spring, after the thaw. Winter is hard on a flat roof. Ice builds up around drains, and CRCA warns that a rapid thaw can do serious damage when meltwater overwhelms flashings and penetrations. The spring inspection finds what winter broke before the summer storms find it.
• Fall, before freeze-up. Leaves, dirt and debris collect over the summer and slow drainage. The fall inspection clears the drains and catches open seams and loose flashing while the roof is still bare and easy to see.

A healthy flat roof drains. Carlisle’s owner’s manual says ponded water should evaporate within 48 to 72 hours after a rain. Water that sits longer points to a blocked drain or a low spot — and going into a Manitoba winter, standing water becomes ice.

Book the fall visit early. The stretch between the last hot week and the first hard frost is short, and a repair list only helps if there is time to work through it before the roof is under snow.

What a proper flat roof inspection checks

A real inspection is more than a walk across the membrane. A 1976 National Research Council Canada digest on flat roofs makes the key point: seals and flashings cover a very small part of the roof, but most leaks happen where they fail. That is where a good inspector spends time.

• Drains, scuppers, gutters and downspouts: open, clear, and letting water leave the roof.
• Flashings and parapet caps: metal that is loose, bent, rusted or open at the joints, and sealant that has cracked or pulled away.
• Roof edges: wind damage often starts at the perimeter, so edge metal, copings and membrane terminations need to be tight.
• The membrane itself: open seams, cuts, punctures, blisters, buckles, ponding, and bare spots where gravel has blown away.
• Penetrations and curbs: the seals and flashings around pipes, vents, skylights and rooftop units, which service work can damage.
• Rooftop equipment: units that move or vibrate, and units leaking oil, grease or other fluids onto the membrane.
• Walls next to the roof: cracked masonry, bad mortar joints and loose caulking can let in water that looks like a roof leak.
• Inside the building: water stains on ceilings and walls, and condensation or rust on the underside of the roof deck.

Oakwood offers roof inspections and planned maintenance programs, and our own sheet metal shop fabricates the flashings, parapet caps and scuppers a flat roof repair often needs.

Inspect again after storms — and after other trades

Twice a year is the minimum. CRCA calls for an extra inspection after any major weather event, including heavy rain, high winds and ice storms. Carlisle says to inspect right after any event with excessive rain, high winds or hail warnings, and FM Global says to inspect after storms.

The June 9, 2026 storm dropped tennis-ball-sized hail in Winnipeg. You cannot see a flat roof from the parking lot, so if nobody has been up since June, you do not know what the hail did to yours.

The other trigger is people. Heating and cooling contractors, electricians, sign installers and solar crews all work on roofs. CRCA recommends an extra inspection after rooftop equipment is installed or serviced, and Carlisle says an inspection should follow regular maintenance of any rooftop unit. Johns Manville warns that dropped tools and heavy equipment can damage the membrane, and suggests keeping a log of every service trip to the roof.

Your warranty probably depends on maintenance

A manufacturer’s roof warranty is not a maintenance plan. Johns Manville’s sample guarantee says so directly: routine inspections and maintenance are the building owner’s sole responsibility, and leaks caused by the owner failing to maintain the roof are not covered. Its maintenance program asks the owner to inspect at least twice a year and keep a file of every inspection and repair.

Carlisle’s owner’s manual recommends inspections every six months for continued warranty service and coverage. It says the owner must keep records, including the warranty, inspection logs, rooftop traffic logs, service logs and invoices.

Watch the reporting deadline too. The Johns Manville sample requires the owner to report a leak immediately, and no later than 30 days after finding it.

Terms differ by manufacturer, product and country — the Johns Manville sample is written for the United States. Find your own warranty and read its maintenance and notice sections. If you cannot find it, ask the roofer who installed the roof.

FM Global, which insures commercial property, gives its clients the same basic rule: inspect the roof and flashings twice a year and after storms, repair what you find, and keep written records. A good roof file holds:

• The warranty and its number.
• Any drawings, specifications or construction details you can collect.
• Every inspection report, with dated photos.
• Every repair invoice.
• A log of who went on the roof, when, and why.

The file also helps you plan. CRCA notes that regular maintenance lets you budget for a new roof and schedule it when it will least disrupt the building.

What your staff can check — and what to leave to a roofer

Some of the best early warnings are inside the building, where your staff already work. Ask them to report:

• New or growing stains on ceiling tiles and walls, especially after rain or a thaw.
• Drips, condensation or rust on the underside of the roof deck.
• White, chalky staining or new cracks on exterior walls.

The roof itself is different. Manitoba’s Workplace Safety and Health Regulation has fall protection rules that apply wherever a worker could fall 3 metres or more, or through an opening in a work surface. Where they apply, the employer needs safe work procedures, trained workers, and a guardrail — or, where a guardrail is not practical, a fall protection system such as travel restraint or fall arrest.

So sending a staff member up with a flashlight is not a safe inspection. Restrict roof access to people who need to be there — CRCA has recommended that since 1970 — and leave the membrane, drains and flashings to a qualified roofing contractor, which is who CRCA says should do the inspection.

The same goes for snow and ice. CRCA’s advice is that a structural engineer should decide whether a snow and ice load is a risk, and that only qualified, insured roofing contractors should remove it. If the weight is not a problem, nothing is leaking and the drains work, CRCA says to stay off the roof.

Infrared and moisture surveys

Some problems do not show on the surface. Water that gets under the membrane soaks the insulation, and wet insulation is hard to find from the top of the roof. The National Research Council digest notes that infrared imaging and moisture meters can locate it.

It is worth finding. The same digest shows how water-damaged insulation lets much more heat escape through the roof, and FM Global tells its clients to replace any wet insulation when repairs are made. Ask your roofer whether a survey makes sense for your building — for example, when a roof has leaked in more than one place, or before you decide between repair and replacement.

What to do this fall

1. Book a fall inspection now, early enough to finish repairs before the roof is under snow.
2. If nobody has been on the roof since June 9, ask the inspector to look specifically for hail damage. If they find some, tell your insurer or broker right away.
3. Find your roof warranty. Read the maintenance and leak-notice sections, and note any deadlines.
4. Start a roof file: warranty, reports, photos, invoices and a roof access log.
5. Set a rule that nobody goes on the roof without sign-off, and that no trade cuts in a new opening without checking the warranty first.
6. Ask staff to report ceiling stains after heavy rain and during the spring thaw.
7. Put a spring inspection on the calendar for when the roof is clear of snow.