Roofing guides · Calgary
You do not need to climb on the roof to know it is in trouble. Ten signs you can check from the driveway and from inside your attic, and a straight answer on which ones mean a repair and which mean the whole roof.
Written by Johnny Anderson, owner of Mountain Standard Roofing Ltd. · Updated 2026-09-05
Most Calgary homeowners find out their roof is finished when water comes through a ceiling. It almost never has to happen that way. The signs you need a new roof show up years before the leak, and nine of the ten below can be checked with a pair of binoculars from your driveway and a flashlight in your attic hatch. Stay off the roof yourself. There is nothing on a roof worth a fall.
Work through the list, count how many you have, and use the repair-versus-replace note under each one.
Stand back at the property line and look along each slope with the light low, morning or evening. Shadows reveal what flat midday light hides. Curling is the shingle edges lifting away from the roof. Cupping is the shingle going concave across its width. Both mean the asphalt in the mat has dried out, lost its flexibility and started to shrink, and both create wind scoops that a chinook gust will find.
Repair or replace: a few curled shingles in one area can be repaired. Curling across two or more slopes is general shingle failure and means replacement.
Look for gaps in the pattern, dark rectangles where a shingle used to be, and shingles with visible splits running through them. Calgary gives you two separate causes here. Chinook wind lifts and tears tabs that are no longer well sealed. Hail cracks the mat and knocks out granules, often in a bruise pattern you can feel more easily than see.
Repair or replace: a handful of missing shingles after a wind event is a repair. Cracking spread across the field is age or hail, and if it is hail we document the damage for your adjuster and handle the claim paperwork. Our Calgary hail claim guide covers the process.
Open your eavestrough or look at the splash pad under a downspout. Those coarse black or grey sand-like grains are the mineral surfacing that shields the asphalt from UV. Some shedding after a new install is normal. Handfuls every spring on a roof past 12 years is not, because once the granules go the asphalt starts baking and the shingle stiffens and cracks. If your eavestroughs are also sagging or leaking at the seams, our eavestrough replacement guide is worth a read while you are up the ladder.
Repair or replace: not repairable. Granule loss is a countdown clock. Heavy loss means you plan the replacement.
This is the next stage past granule loss. Look for shiny black, grey or brown patches where the surface looks smooth instead of textured. That is the fibreglass mat with nothing over it. In Calgary’s UV and freeze-thaw exposure a bald patch progresses to a crack, and a crack lets water into the mat where the next freeze splits it open.
Repair or replace: visible mat on more than a small area means replace. The shingle has no protective layer left.
Sight along the ridge and along each eave from the corner of your lot. They should be straight lines. Dips, waves, a swaybacked ridge or a rippled roof plane are the most serious items on this list, because they are structural rather than cosmetic. Causes include sheathing that has been wet long enough to delaminate, a compromised rafter or truss, or snow load on an already weakened structure. Part 4 of the National Building Code, Alberta Edition sets Calgary’s design snow load, and valleys and roof-to-roof transitions collect drift well beyond the flat-ground number.
Repair or replace: call someone now, regardless of season. This is the one sign not to sit on.
Calgary is dry, so we see far less moss than the coast, but it shows up on north-facing slopes under mature trees, especially in the older inner-city neighbourhoods. Moss holds moisture against the shingle and its root structures work into the mat, so the slope stays wet through more freeze-thaw cycles than it should.
Repair or replace: moss alone is a cleaning and ventilation issue, not a replacement trigger. Never pressure wash asphalt shingles, it strips the granules. Moss plus curling on the same slope means the slope is finished.
Pick a bright day, take a flashlight, open the hatch and look before you climb. Step only on the ceiling joists, never on the insulation, and never into an attic under a visible sag.
Turn the flashlight off and let your eyes adjust. Pinholes or thin lines of daylight through the sheathing mean gaps in the deck, and where light gets through, wind-driven rain and blowing snow get through too. Check around the chimney, plumbing stacks and roof-to-wall transitions first, since flashing failures show up there before anything else.
Repair or replace: a single defined spot around a penetration is usually a flashing repair. Light in multiple places means the deck and the roof over it are done.
Dark tide lines, rings and streaks on the underside of the deck are a record of past water. Run a hand over any stained area. If the wood feels soft, spongy or the plies separate, that sheet is going to be replaced when the roof comes off. Fresh dark staining after a chinook thaw is an active problem.
Repair or replace: localised staining under one valley or one chimney points to a specific flashing failure to repair. Staining spread across multiple bays means the roof has been leaking generally.
Look in mid-winter. White frost or ice crystals coating the underside of the deck and the nail points is one of the most common attic findings in Calgary, and it is not a roof leak. It is warm, moist household air escaping through ceiling penetrations into a cold attic and condensing. When a chinook arrives it melts all at once and drips onto insulation and ceilings. Homeowners call it a leak. We call it attic rain, and it is covered in detail in our attic rain guide.
The fix is air sealing, added insulation and correct ventilation, not new shingles. Natural Resources Canada’s Keeping the Heat In guidance sets the working ventilation rule for a peaked roof with an accessible attic at an unobstructed vent area to insulated ceiling area ratio of 1 to 300, with roughly half of that as continuous soffit intake, and notes that a well-sealed, well-insulated attic produces a cool roof that generally will not form ice dams.
Repair or replace: neither. This is attic insulation and ventilation work. Do it at the same time as a roof if the roof is also due.
Find out what went on the house and when. In Calgary, expect 15 to 20 years from old 3-tab shingles, 25 to 30 from architectural asphalt, and 25 to 30 from 1990s cedar shake, which puts a lot of Calgary shake roofs at the end of the line right now. Our cedar shake conversion guide explains what that job involves, and why insurers have started pushing back on old wood shake.
The repeat-repair pattern is the other half of this. If you have paid for three separate repairs in four years and they keep appearing in new places, you are not fixing a roof, you are paying for a slow replacement one visit at a time. Add up what you have spent. Two thousand dollars of patching on a 24-year-old roof is money that should have gone toward the new one.
Repair or replace: past 20 years with multiple failure points, replace.
If your roof is showing these signs at 18 years and the shingle carried a 30-year label, you were not cheated. Calgary is genuinely one of the hardest roofing climates in Canada.
Our chinook roof damage guide goes deeper on the freeze-thaw failure mode and what to inspect after a chinook.
We give homeowners the same three-part test on every driveway.
If it is one section, roof repair is the smarter spend and we will tell you so. If it is the whole roof, residential roof replacement is the honest answer, and our 2026 Calgary cost guide shows what that runs. Timing matters too, and our seasonal guide explains why late spring to early fall is ideal.
Mountain Standard Roofing inspects and replaces roofs across Calgary, Airdrie, Cochrane, Okotoks and High River. If hail is in the picture, see hail damage and insurance work. Finished jobs are in the gallery and homeowner feedback is on our reviews page.
Book a free on-site inspection and we will photograph every slope, show you what we found and tell you plainly whether it is a repair or a replacement, backed by a written warranty. Most re-roofs done in one to two days. Call (587) 577-6170 or request a quote. Built for the harshest conditions.
Questions homeowners actually ask
How do I know if I need a new roof or just a repair?
The dividing line is whether the failure is local or general. Damage in one place with a clear cause, such as wind lifting a few shingles or a failed pipe boot, is a repair. Failure showing up across multiple slopes at once, such as curling, granule loss and bald patches everywhere, means the shingles themselves have reached the end of their service life and patching them just buys months. Age matters too. Past 20 years in Calgary, repairs stop being good value.
How long should a roof last in Calgary?
Architectural asphalt shingles give 25 to 30 years of real service here. Older 3-tab shingles give 15 to 20. Cedar shake from the 1990s is at 25 to 30 and effectively done. Calgary is harder on roofs than most of Canada because of roughly 107 freeze-thaw cycles a year plus hail and chinook wind, so treat manufacturer lifespan claims as an optimistic ceiling, not an expectation.
Are granules in my gutters a serious problem?
It depends on the volume and the roof's age. A cup of granules after a new roof is installed is normal shedding of loose material. Handfuls of granules every spring on a 15-year-old roof means the mineral surfacing that protects the asphalt from UV is wearing away, which is the beginning of the end. If you can see the black or grey fibreglass mat through the surface anywhere, the shingle has no UV protection left in that spot.
Does a sagging roofline always mean structural damage?
A visible dip, wave or ridge sag in the roof plane is the one sign on this list to treat as urgent. It can mean sheathing that has been wet long enough to delaminate, a rafter or truss issue, or accumulated snow load on a compromised structure. Do not wait for spring on a sag. Get someone to look at it, and stay out of the attic directly under it.
What does frost in the attic mean?
It means warm, moist household air is leaking into a cold attic and condensing on the sheathing. That is attic rain, and it is not a roof leak, even though it stains ceilings exactly like one. The fix is air sealing, insulation and ventilation, not shingles. It is worth knowing which one you have before you spend money, and it is a very common Calgary problem in winter.
Is moss on a Calgary roof a reason to replace?
Not on its own. Calgary is dry, so heavy moss is less common here than on the coast, and where we do see it, it is on north-facing slopes under trees. Moss holds moisture against the shingle and its roots work into the mat, which accelerates the freeze-thaw damage the shingle is already taking. Have it removed properly rather than pressure washed, and treat it as a warning that the slope is staying wet longer than it should.
We will get up there, photograph every slope and every penetration, and tell you honestly whether it is a repair or a replacement. Free on-site inspection, no obligation.
★★★★★ 5.0 out of 5 — 10 Google reviews
Every review below is a verified Google review of Mountain Standard Roofing Ltd. Backed by our 10-year written workmanship warranty. Built for the harshest conditions.
★★★★★
“Mountain Standard Roofing handled my storm damage roof replacement perfectly. They worked directly with my insurance company, handled all the paperwork, and made the entire process stress-free. The crew was professional, efficient, and left my yard clean.”
Nikki Rick — Google review
★★★★★
“John and his team were awesome to deal with. He did my roof and siding and they finished a day ahead of schedule. Not only was the service awesome but the price was much better than competitors.”
Kristoffer — Google review
★★★★★
“The owner John is very communicative and always took time to answer our questions. Our roof was re-done in the agreed timeline and for the agreed upon price. Would highly recommend doing business with Mountain Standard Roofing.”
Ryan Van Boven — Google review