How to Tell If Your Shingles Are Drying Out

A roof does not usually announce that it is drying out. It fails on a specific afternoon, months or years after the process that caused it started. Everything useful happens in between, and almost all of it is visible from the ground if you know what you are looking at.

This is a checklist you can run yourself, in about fifteen minutes, without a ladder. Do it in the early morning — low sun rakes across the roof surface and shows texture that midday light flattens out completely.

What “drying out” actually means

An asphalt shingle is a fibreglass mat saturated in asphalt and surfaced with ceramic granules. Three layers, three jobs. The granules block UV. The asphalt is the waterproofing and the flexibility. The mat is the structure.

Heat and ultraviolet light drive the lighter compounds out of the asphalt over time. What is left is harder and more brittle, and it shrinks slightly as it goes. That shrinkage is the mechanism behind nearly every sign below — a stiffening shingle pulls against its own granules, its own edges, and the nails holding it down.

In the Valley this runs faster than the same shingle would run in a milder climate, for reasons that are not complicated: more sun, more of it, hotter. A dark roof surface in a Phoenix July gets far above air temperature, and the material does not get a cool season to recover in.

The seven signs, in the order they usually appear

1. Colour that has gone flat

The earliest sign, and the easiest to dismiss because it happens to the whole roof at once. Compare the main field of your roof against a section that lives in shade — under a tree, on a north face, behind a parapet. If the shaded area is noticeably richer in colour, that difference is the UV exposure the rest of the roof has taken.

This alone means very little. It is worth noting because it dates the process.

2. Granules in the wrong places

Granules end up in gutters, at the base of downspouts, and in the gravel or planting bed under the drip line. A new roof sheds loose granules for its first season — that is manufacturing overspray and it stops.

What matters is granules appearing years in. Look at the downspout outlets after a rain. A visible accumulation, rather than a scattering, means the asphalt is no longer holding them.

3. Bald patches with a pattern

Once granule loss is advanced enough to see from the ground, it appears as darker, shinier patches where the asphalt underneath is exposed. The pattern matters more than the size:

• Patches concentrated on the south and west planes are UV. That is the drying process.
• Patches in straight lines down the roof usually mean water is being concentrated — a valley, a gutter overflow, or run-off from an upper roof.
• Patches in a scattered, dented pattern are usually hail.

Only the first one is a drying-out sign. The other two are worth knowing about for different reasons.

4. Edges that have curled or cupped

A shingle that has shrunk pulls its own corners up. From the ground this reads as a roof surface that is no longer smooth — the courses cast small shadows where they should lie flat, and the texture looks slightly rippled in raking light.

This is a meaningful threshold. Curling means the shrinkage is far enough along to overcome the weight of the shingle and the seal holding it down.

5. Cracking

Fine cracks across the face of a shingle, often in a rough grid. Hard to see from the ground on a steep roof, sometimes visible on a low-slope section or from an upstairs window of a two-storey neighbour.

Cracking is the line between two situations. Before it, the shingle is intact and stiffening. After it, the mat is exposed and the shingle is failing. Treatment addresses the first and does nothing for the second — that boundary is covered in more detail on the roof rejuvenation page, including the roofs it excludes.

6. Shingles that lift in wind

Watch the roof during any windy afternoon. Sealed shingles do not move. If you can see individual shingles or courses lifting, the seal strips have let go — either because the adhesive has aged out, or because the shingle has stiffened enough to peel itself off.

7. Nail heads showing

Late-stage. As shingles shrink they can pull up over their own fasteners, and as the deck moves nails can back out. Either way, a nail head sitting proud of the surface is a hole in the roof with a piece of metal in it.

The fifteen-minute version

What the signs together are telling you

No single item on that list decides anything. The pattern does.

A roof with flat colour and nothing else is early and fine. A roof with flat colour, granules in the downspouts, and bald patches on the west plane is well into the drying process and is a candidate for treatment while the shingle is still intact. A roof with curling, cracking, and lifted shingles has crossed out of that window, and the useful conversation there is about replacement — including the honest version, which is that a roof at that stage does not need to be replaced this month, it needs a plan and a budget.

What this check cannot tell you

Two things, both worth stating.

The first is anything about the decking underneath. A soft or delaminated deck is invisible from the ground and is a different problem with a different answer.

The second is condition on any plane you cannot see. Most houses have at least one, and it is often the one that faces the direction that matters most.

Those are the gaps a proper inspection fills. But running the list above first means you arrive at that conversation knowing what your own roof looks like, which is a considerably better position than taking someone’s word for it.