JUMP TO A SECTION
Most homeowners never watch their own roof get installed, and even the ones who do are not trained to know what good work looks like versus bad. That gap is exactly where a rushed crew, a subcontractor cutting corners, or an out-of-town outfit that skipped town after a storm can leave problems baked into a roof that looks fine from the street on day one. Some of what follows is cosmetic, and some of it is the kind of defect that turns into a claim against the contractor. This guide walks all twelve, in the order you would actually spot them: from the driveway, at the edges, in the flashing, and finally in the attic, where the truth usually shows up first.
Everything in this guide can be checked from the ground or with a phone camera zoomed in. It is not a reason to climb a ladder mid-install and start pointing at shingles. Raise concerns with the contractor directly, and if you want a second set of trained eyes, that is exactly what a final walkthrough inspection is for.
01 / THE SHORT ANSWERWhy installation quality matters more than the shingle brand
Two roofs can use the identical shingle, from the identical manufacturer, and age nothing alike. The material is engineered to a spec; the installation is done by hand, on a schedule, sometimes in a hurry, and that is where quality actually lives or dies. A premium architectural shingle laid with racked courses, missing starter strip, and reused flashing will leak years before a mid-grade shingle installed correctly. That is the uncomfortable truth behind most of the new roof leaking calls we get: the material was never the problem.
The list below is organized the way you would actually find these problems: easiest to hardest to spot, cheapest fix to most expensive one. If you are watching a job in progress, sections 02 through 04 are what you can check today. If you are trying to figure out why a roof someone else installed is already giving you trouble, all twelve apply, and section 05 on the attic is often where the real answer is hiding.
02 / FROM THE DRIVEWAYFour signs you can see without a ladder
1. Wavy or bowed shingle courses
Stand at the curb and look at the horizontal lines the shingle tabs form across the roof. They should run straight and parallel, like ruled lines on paper. Waviness usually traces back to a deck that was not properly prepared, chalk lines that were not snapped or were ignored, or a crew working too fast to keep courses aligned. On its own a slight wave is mostly cosmetic, but pronounced waviness can mean the deck itself has soft spots or was never properly fastened, which is worth flagging rather than shrugging off.
2. Racked, out-of-alignment cutouts
Look at the vertical joints between shingle tabs. On a properly racked roof, those joints step diagonally in a consistent pattern up the slope. When a crew installs in straight vertical columns instead of the manufacturer's offset pattern, the cutouts between tabs can line up directly on top of each other course after course, which creates a channel where wind-driven rain has an easier path to work through the shingle layers instead of shedding across them.
3. Color or lot mismatches
Shingles are manufactured in production lots, and color can vary slightly between lots even on the same product line. A careful installer blends shingles from multiple bundles as they work so any variation is scattered and invisible. A rushed or careless crew works straight through one stack at a time, and the result is a visible band or patch where the color noticeably shifts. This one is purely cosmetic, it will not cause a leak, but it is a fast tell for how much care went into the rest of the job.
4. Exposed nail heads
Every shingle has a nailing zone designed to be covered by the course above it. Nails placed too high, or a whole course installed too low, leave fastener heads sitting in the open weather instead of tucked under the overlapping shingle. An exposed nail head is a guaranteed future leak point: the shank creates a puncture through the shingle and, eventually, through the sealant a homeowner or handyman dabs over it. Our companion guide on hand-nailing versus nail gun installation covers how fastener placement problems like this actually happen on a real job site.
03 / THE EDGES AND RIDGEThree signs where the roof meets its own trim
5. Missing or wrong starter strip and drip edge
The starter strip is the first course laid at the eave, designed to seal the tabs above it and stop wind from getting underneath the first row of visible shingles. Drip edge is the metal trim at the eaves and rakes that directs water off the roof and away from the fascia instead of behind it. Skipping either, or using a strip of cut field shingles as a homemade starter, is a shortcut that saves a crew maybe twenty minutes and costs the homeowner a wind-lifted first course or fascia rot within a few seasons.
6. Ridge caps cut from field shingles
The ridge, the highest and most wind-exposed line on the roof, is supposed to be finished with cap shingles engineered and rated specifically for that job, thicker and built to bend over the ridge without cracking. Some crews cut standard three-tab field shingles into thirds and use those instead, because it is faster and uses leftover material. Cut field shingles were never engineered for the ridge's wind exposure or bend radius, and they are one of the most common reasons a ridge line is the first thing to blow off in a real Michigan wind event.
7. Ridge vent installed incorrectly
A ridge vent needs a properly sized slot cut in the deck, the vent baffle set correctly over it, and cap shingles nailed at the length specified for that product, not the standard field-shingle nailing pattern. Get any of that wrong and you can end up with a ridge vent that looks fine from the ground but does not actually exhaust attic air, which quietly undermines the ventilation the rest of the roof depends on to stay dry and prevent ice damming in winter.
04 / THE FLASHINGThree signs where water actually gets in
8. Reused old flashing
Step flashing at a wall, counter flashing at a chimney, and valley metal all have a working lifespan, and reusing the old pieces on a new roof is a corner some crews cut to save material cost. Old flashing that has already rusted, bent, or lost its seal is not going to perform any better under a brand-new set of shingles than it did under the old ones. New flashing at every wall, chimney, and valley tie-in should be standard on any full replacement, not an upgrade.
9. Sloppy pipe boots and penetrations
Every plumbing vent, exhaust stack, and roof penetration needs a properly sized boot, shingled in correctly so water sheds over it rather than around it. A rushed installer sometimes leaves a gap around the pipe and relies on a bead of roofing sealant to close it instead of fitting the boot and shingle courses correctly. Sealant is a maintenance item, not a substitute for a properly integrated boot, and it is one of the fastest sources of a leak in the first year or two after installation.
10. Valley errors
Valleys carry more water than any other part of the roof, and there is more than one acceptable way to build one, open metal or a properly woven or closed-cut shingle valley, but each method has a correct way to do it. Common mistakes include nailing too close to the valley centerline, using undersized metal, or cutting a closed valley too tight so water has nowhere to go but under the shingle edge. A valley done wrong tends to show up as a leak inside the house well before it shows up as anything visible on the roof.
A roof does not fail at the field shingles nearly as often as it fails at the details: the edges, the flashing, and the valleys. That is where the eye of a rushed crew and the eye of a careful one part ways.
05 / THE ATTICTwo signs only the attic reveals
11. Shiners
A shiner is a roofing nail that missed the rafter or truss chord entirely and is only holding by the sheathing. From the attic, on a cold morning, a shiner often shows up as a small ring of frost or a pinprick of daylight where the nail tip protrudes through the underside of the deck. A shiner does not leak by itself, but it is a loose fastener holding shingles that were supposed to be anchored solidly, and a roof with more than a few of them was installed by a crew not paying attention to what they were shooting into.
12. Daylight or gaps at deck seams and tie-ins
Standing in the attic on a sunny day and looking up toward the roof deck should show a solid, unbroken surface with no visible light. Gaps at deck seams, around a chimney chase, or where flashing ties into the framing are places builders sometimes leave unsealed or under-flashed, and they are effectively a preview of exactly where the next leak will start. This is the single most reliable check in this entire guide, and it is also the one homeowners are least likely to do on their own, which is why it is a standard part of any thorough post-install walkthrough.
06 / THE VERDICTCosmetic or claim-worthy: sorting the twelve
Not everything on this list means the same thing, and treating a cosmetic issue like an emergency, or a claim-worthy defect like a nitpick, both waste time. Here is how the twelve generally sort out.
| SIGN | TYPICAL VERDICT |
|---|---|
| Wavy or bowed courses | Usually cosmetic; worth checking the deck if pronounced |
| Racked, misaligned cutouts | Cosmetic to functional depending on severity |
| Color or lot mismatch | Cosmetic only, no leak risk |
| Exposed nail heads | Claim-worthyfuture leak point |
| Missing starter or drip edge | Claim-worthywind and fascia risk |
| Cut-shingle ridge caps | Claim-worthywind uplift risk |
| Ridge vent installed wrong | Claim-worthyventilation failure |
| Reused old flashing | Claim-worthyleak risk |
| Sloppy pipe boots | Claim-worthyactive leak risk |
| Valley errors | Claim-worthymajor leak risk |
| Shiners in the attic | Watch item; loose fastener, rarely urgent alone |
| Daylight at deck seams | Claim-worthyactive or coming leak |
The claim-worthy column is where a workmanship warranty conversation belongs, not a legal fight. A contractor who stands behind their work will send someone back out to correct a flashing detail or replace a bad ridge cap section without an argument. If the roof was installed within the last few years and the installer is unresponsive, our guide on what to do about a new roof already leaking walks the workmanship warranty path in detail.
Correcting a flashing detail, a valley, or a handful of boots generally falls in the standard repair range of $350 to $3,200, the same published range on our pricing sheet. Widespread problems across an entire roof, poor nailing pattern throughout, ridge caps done wrong on every slope, can cross into replacement territory, which is exactly what a free inspection is for: telling you honestly which side of that line your roof is on.
07 / THE REAL ANSWERGetting a real answer, free
Reading a driveway survey and an attic check is a good start, but a trained inspector catches details a homeowner's eye will miss, especially the ones that require getting on the roof itself: nailing pattern up close, flashing tie-ins under a chimney cricket, whether a valley was woven or cut correctly. Our second-opinion inspection is $0 with no obligation, whether the roof was installed by us, by another local contractor, or by a name you can no longer find. If the work is sound, we tell you that plainly. If it is not, you get photos of exactly what we found and an honest read on whether it is a warranty call to the original installer or a job for someone else.
Timing matters here too. A rush of storm-chaser crews came through Macomb County after the wind events of August 2023 that led to federal disaster declaration DR-4757, and some of that work was excellent and some of it was exactly the shortcuts described above, done fast by an out-of-town crew that was gone before the first winter tested the ridge caps. If your roof was installed in that window and you have never had it looked at since, that alone is a reason to get a free second opinion. Our storm and insurance claims guide covers what happens when storm-driven defects turn into a claim conversation.
If you are still in the middle of a project and want to know what a careful crew's final walkthrough actually checks, our how to inspect your new roof before the crew leaves guide is the natural next read, and the cost calculator is there if a repair or a redo turns out to be the answer.
- Wavy courses, racking, color mismatch, and exposed nails are the four signs visible from the driveway.
- Missing starter strip, cut-shingle ridge caps, and a poorly installed ridge vent show up at the edges and ridge.
- Reused flashing, sloppy pipe boots, and valley errors are where installation defects actually turn into leaks.
- Shiners and daylight at the deck seams are attic-only signs, and the deck-seam check is the most reliable one in this guide.
- A free second-opinion inspection sorts cosmetic issues from claim-worthy ones with photos, no obligation.
Questions we hear most
Start with what you can see: straight, evenly blended shingle courses, a proper starter strip and drip edge at the eaves, and real cap shingles at the ridge rather than cut field shingles. From there, a look in the attic on a sunny day for daylight at the deck seams tells you more than anything visible from the ground. A trained final walkthrough or second-opinion inspection catches what a homeowner's eye will miss.
Not always. A slight wave is often cosmetic and traces back to normal deck variation or a fast install, and it will not by itself cause a leak. Pronounced waviness is worth mentioning to the contractor or flagging in an inspection, since it can occasionally point to a deck issue underneath, but it is not automatically a claim-worthy defect on its own.
Document what you are seeing with photos, then raise it with the installing contractor under the workmanship warranty, since a legitimate company will typically send someone back to correct real defects. If the installer is unresponsive or no longer in business, a free second-opinion inspection gives you photos and an honest read on whether the fix is a targeted repair or something bigger.
- FEMA, disaster declaration DR-4757-MI, Michigan severe storms of August 2023 (Macomb County designated). fema.gov/disaster/4757
- Michigan Residential Code 2015, section R905.2 Asphalt Shingles: fastening, slope, and underlayment application requirements. up.codes: MRC chapter 9
- National Roofing Contractors Association, technical guidance for steep-slope roof systems. nrca.net
- Manufacturer technical and warranty literature for the major asphalt shingle lines: GAF (gaf.com), Owens Corning (owenscorning.com), and CertainTeed (certainteed.com).