Local or widespread
When you see a defect on a shingle roof, the first question is whether it is local or widespread.
A local problem affects one precise spot. Three shingles blown off near the rake edge, a crack around a vent, a corner damaged by a branch. The rest of the roof is sound. A repair is enough.
A widespread problem shows across a whole slope, or all of them. The shingles have aged together. Repairing one spot only pushes the next call back a few months.
Age helps decide. Asphalt shingles last 15 to 30 years, depending on the manufacturer and the quality of installation. Widespread defects on a roof within that range point to a replacement.
Defects from age and heat
Over the years, the sun dries out the asphalt. The shingle loses its flexibility, shrinks slightly and changes shape.
- Curling shingles. The corners lift or the centre bulges. Heat from a poorly ventilated attic speeds this up.
- Granule loss. Smooth, dark patches appear, and the gutters fill with coloured sand.
- Cracks. Splits run through the shingles, often in lines that follow from one course to the next.
Curling, granule loss and cracks come with every aging roof. If they show up early, look for a cause, such as poor ventilation, moisture in the attic or a manufacturing defect.
Defects from wind
Wind attacks the edges, meaning the rakes, the ridge and the bottom of the slopes.
- Missing shingles. Darker rectangles show the underlayment or the course below.
- Unsealed shingles. The adhesive strip has let go. The shingle flaps in the wind and will end up breaking at the nail line.
Installation defects
Some problems have nothing to do with wear. They date from the day of installation.
- Badly placed nails. Too high, they hold only one layer. Driven too deep, they go through the shingle.
- Nail pops. A nail pushes up the shingle above it and ends up piercing it. The cause can be the installation or the wood shifting.
- Neglected flashing. Tar spread around a chimney instead of metal pieces only holds for a while.
Stains and growth
Black streaks on a north slope are algae. Green cushions are moss. Algae is mostly a matter of appearance. Moss holds water and can lift the shingles.
Decking that gives way
Seen from the street, a roof should be straight. A dip between two rafters or a wavy ridge line shows that the wood under the shingles is affected. The problem then goes beyond the roofing. The roof has to be opened to see how far it goes.
What to do when you see a defect
- Look from the ground, with binoculars if needed. Do not go on the roof.
- Photograph the defect and note the date.
- Have us look at the roof, and ask us whether the problem is local or widespread. As with any contractor, check the licence in the RBQ register.
Frequently asked questions
Do a few damaged shingles mean the whole roof needs replacing?
No, a few damaged shingles do not mean the whole roof needs redoing. If the rest of the roof is flexible, well covered with granules and lying flat, the damaged shingles get replaced. A full replacement comes up when the defects cover a slope or repairs keep coming back.
Can a roof be worn out without leaking?
Yes, a roof is often worn out without leaking. The underlayment and the overlap of the courses hold back water for a while even when the shingles are at the end of their life. Waiting for a leak risks damaging the decking and the insulation.
Does the manufacturer's warranty cover these problems?
The manufacturer's warranty covers manufacturing defects, under certain conditions, and rarely normal wear or poor installation. Reread the warranty and keep your invoice. Installation falls under the workmanship warranty of the contractor who installed the roof.