The Fall Roof Check From the Ground: Shingle, Flashing and Vent Signs Visible Without a Ladder

Now for the broad expanse of shingles, where distance genuinely helps. Up close, a roof is a thousand individual pieces. From across the street, it is a pattern — and pattern is the diagnostic.

Buckling, and the Straight-Line Test

If you can see ridges or waves running across the shingle field, look carefully at how they are arranged. The Asphalt Roofing Manufacturers Association draws a distinction here that works beautifully at thirty metres. Moisture-induced deck effects typically show distortions coincidental with the joints in the roof deck panels or lumber, which appear as regular, straight, evenly spaced lines. Distortion caused by wrinkled underlayment, by contrast, is random throughout the roof area and not aligned with deck joints.

That difference changes who you call. And there is a further point in the same bulletin that homeowners almost never hear: the association attributes deck movement partly to inadequate ventilation of the attic space, because restricted airflow beneath the deck creates moisture and temperature problems that move the wood. The defect you can see is on the shingles. The cause may well be under them.

Curling, Cupping and the Cold-Morning False Positive

Shingle edges that lift are not all the same thing, and the terms get used interchangeably in a way that causes real confusion. Cupping and clawing describe different shapes with different causes and should not be treated as one condition.

More practically, for an article you are probably reading in sweater weather: IKO documents a distinct phenomenon called winter curling, in which the front edge of a shingle tab lifts into a shallow saucer shape in cold weather and flattens again once it warms up. It is a manufacturer-documented, reversible condition.

Most homeowners scan the field of shingles and ignore the fiddly bits. This is backwards. The interruptions in a roof — chimneys, walls, skylights, valleys and pipes — are where water finds its way in, and one of them is both the likeliest failure point and genuinely visible from the ground.

Every house has plumbing vent pipes poking through the roof, each sealed by a boot: a rubber collar over a metal base flashing. Roofing contractors report that these rubber collars are the component most likely to fail well before the shingles do, typically needing replacement somewhere around ten to fifteen years as ultraviolet exposure dries and cracks the rubber. One contractor's inspection guidance on pipe boots treats cracks deeper than a quarter-inch as failure, and notes that shingle service life has lengthened over recent decades while boots have not.

Silhouetted against the sky, a split collar is one of the more readable things on a whole roof. Point the binoculars at each vent pipe and look for a collar that has gone hard and grey, split along its folds, or pulled away from the pipe.

There is a related trap worth knowing about. Contractors frequently find that budget re-roofing jobs leave the old pipe boots and flashings in place when the shingles are replaced, which leaves components of wildly different ages all sharing the job of keeping water out. If your roof was redone five years ago and you have a mysterious leak near a vent pipe, that is a very plausible explanation — and "are you replacing all the flashings and boots" is now a question for your next roofing quote.

Chimney flashing, sidewall step flashing and skylight perimeters deserve a look too, though here honesty requires a caveat. You can sometimes see obvious failure from the ground — visibly lifted metal, a gap you could post a letter through, rust staining running down brick. What you cannot see is the condition of the sealant in a chimney reglet or whether step flashing was woven correctly under the shingle courses. Those are close-access questions. If you are already seeing water indoors, our guide to early leak detection and emergency fixes is the more urgent read.

Ventilation has come up twice already as a cause hiding behind a visible symptom, so it earns its own pass. The encouraging part is that a roof ventilation system has two halves, and the half most people forget is the half at eye level.

Attic venting works as a pair: intake low at the soffits, exhaust high at the ridge or through roof vents. Part 9 of the building code requires vent area of at least 1/300 of the insulated ceiling area, rising to 1/150 for shallow slopes and roofs built with roof joists, and it requires those vents to be distributed uniformly on opposite sides of the building with at least a quarter of the openings at the top of the space and at least a quarter at the bottom.

That bottom quarter is your soffit, and you can inspect it properly without leaving the ground. Walk the perimeter looking up into the underside of the overhang. Are the soffit panels actually perforated, or are they solid? Have they been painted over so thoroughly that the perforations are sealed? Is there insulation visibly stuffed against them from inside, or a bird's nest, or a mat of debris? A roof with a continuous ridge vent and blocked soffits is not a balanced system, and it is a documented deficiency rather than a matter of taste.

While you are looking up, find where your bathroom and kitchen exhaust fans terminate. Canadian code requires exhaust ducts to discharge to the outdoors, so a duct that simply ends loose inside the attic fails that plainly. A duct that terminates at a vented soffit is a subtler problem: the soffit is the attic's air intake, so warm, moist house air gets delivered directly to the opening that feeds the attic. Look for a proper hood on an exterior wall or through the roof, and note any duct that seems to vanish into the overhang.

Two roofs on the same street can carry two kinds of dark patch that mean opposite things, and confusing them is expensive in both directions.

The black streaking that runs down roof planes across Canada is algae — most commonly gloeocapsa magma, which produces a dark pigmented sheath to protect itself from ultraviolet light. And on the authority of the shingle manufacturers' own association, it is cosmetic. Their guidance on algae and moss states plainly that there is no scientific evidence algae damages asphalt shingles, though it certainly affects appearance. If dark streaking is the only thing you have found, you have not found a reason to replace a working roof.

Moss is a different story entirely, and the same association is equally clear about it. Moss can be detrimental to shingle performance: it lifts and curls the leading edges of shingles, which raises the risk of blow-off in wind, and heavy build-up can move water sideways across the roof rather than down it, damaging the deck or causing leaks. Moss tends to favour north-facing planes that get less sun and stay damp longer — which is exactly why walking all four elevations separately is worth the extra five minutes.

The distinction is visual and you can make it from the ground. Algae reads as flat staining that follows water flow, in streaks running down the slope. Moss reads as texture — raised green or grey-green cushions with visible depth, usually thickest along shingle edges and in shaded areas.

One warning applies to both. Never use a pressure washer on an asphalt shingle roof; the association is unambiguous that it strips granules and very likely causes premature failure of the roof system. The recommended approach is a fifty-fifty mix of laundry-strength chlorine bleach and water, applied with a sprayer, left to dwell for fifteen to twenty minutes, then rinsed with low-pressure water. It is genuinely possible to diagnose a harmless stain correctly and then cause real damage removing it.

Everything so far has been outdoor observation. There is one more check, it costs nothing, and it is the single best confirmation of a ventilation suspicion — but it is seasonal, so think of it as the December follow-up to your October walk.

After a genuine cold snap, open the attic hatch and look. Natural Resources Canada's guidance on roofs and attics gives a rare and useful number here: some frost build-up is to be expected, but particularly heavy build-up of 10 mm (3/8 in.) or more is the signal to check that ventilation is present and not blocked with insulation.

Ten millimetres. That is roughly the thickness of a pencil, and it is the difference between "normal Canadian attic in January" and "something needs attention." The same guidance recommends that ideally half the attic ventilation openings be continuous soffit vents and the other half gable, ridge or roof vents — and it advises against powered attic fans, which can pull more air than the soffits can supply and end up drawing house air into the attic, making both heat loss and moisture accumulation worse.

The moisture itself is more domestic than most people realize. It is not coming from a leak. It is the water your household puts into the air every day through cooking, bathing, laundry and simply breathing, rising into a space that was never meant to receive it.

This is the part that turns a list of findings into a decision, and it hinges on a number most homeowners have never encountered: repairs to a roof are governed by a physical temperature floor, not by a contractor's preference.

Henry's Canadian product page for its Plastic Roof Cement 810-20, a standard Canadian roofing mastic, instructs users to apply it between 5 °C and 30 °C, states plainly that it should not be applied below 5 °C, and requires a dry surface. That second requirement quietly rules out a great many autumn mornings regardless of what the thermometer says, because a frosted or damp roof is not a dry one.

Now set that floor against the calendar. Using indicative monthly averages published by Statistics Canada — drawn from an older normals period, so treat them as a rough guide rather than a forecast — October average daily temperatures sit above the 5 °C floor almost everywhere: Toronto near 8.9 °C, Halifax 8.3 °C, Ottawa 7.8 °C, Vancouver 10.1 °C, and even Calgary and Winnipeg just above at 5.4 °C and 5.3 °C. By November the picture inverts across much of the country. Winnipeg averages around −5.3 °C, Regina −5.5 °C, Edmonton −5.7 °C, Calgary −3.1 °C, Quebec City −0.7 °C, while Vancouver, Victoria, Toronto, Windsor and Halifax stay nearer the line.

The practical consequence is a working window that differs by roughly a month depending on where you live. A reader in Vancouver and a reader in Saskatoon doing the same walk on the same October weekend are on genuinely different clocks, and that is the strongest argument for doing this in early October rather than late November.

None of which means cold-weather roofing is impossible — only that it is different. IKO's own cold-weather instructions call for shingles to be installed between roughly 4 °C and 26 °C, stored warm so they are not brittle, and hand-sealed when conditions are cold: six nails instead of four, and three quarter-sized dabs of roofing cement under each tab, because the self-sealing strip is heat-activated and will not bond on its own in the cold.

An honest method needs honest limits, and these are worth stating without hedging.

You cannot see underlayment condition, deck rot beneath intact shingles, fastener corrosion, the state of sealant inside a chimney reglet, whether step flashing was woven correctly, or the integrity of a valley detail. You cannot assess anything on a low-slope section that is hidden by the pitch of the roof. And you certainly cannot tell how many winters the roof has left.

That last limit is not a failure of your binoculars. The National Standards of Practice explicitly relieve professional inspectors of any requirement to determine the remaining service life of a component, the causes of a condition or deficiency, future conditions including failure, or compliance with codes and regulations. If someone standing on your roof with twenty years of training is not expected to forecast its remaining life, the expectation was unreasonable from the driveway too.

So what does escalation look like? The Roofing Contractors Association of British Columbia is refreshingly candid on this point: an inspection by a qualified roofing contractor or roof inspector is the best way to determine the condition of your roof, and while inspectors and consultants charge for their services, the result is generally an unbiased assessment. That is the roofing industry's own association noting the incentive difference between a paid inspector and a free look from someone hoping to sell you a roof. It is worth weighing when you make the call.

Your fifteen minutes have not replaced that inspection. What they have done is far more valuable than it sounds: you now know whether you need one, which specific things to point at when the inspector arrives, and — just as importantly — which of your worries you can let go of entirely. Our guide to professional roof inspections in Canada covers what a proper inspection includes and what it should cost.