What granules are doing there
The granules are the shingle’s armour. They shield the asphalt underneath from the sun, they give the roof its colour, and they take the wear that weather would otherwise put on the bitumen.
When they leave, the asphalt is exposed, which is why heavy granule loss tends to be followed by faster drying and more UV damage.
What makes them leave
Age and heat are the main drivers: the asphalt hardens and loses its grip on the granule bed. Water and freeze-thaw speed it up, because water that gets into the shingle expands when it freezes and pushes the surface apart from the inside.
New shingles also shed granules in their first year, which is normal in small amounts. A steady flow into the gutters after a decade or more is the pattern that matters.
- Granules collecting in gutters and at the foot of downpipes
- Bare, dark patches where the asphalt shows through
- A rougher surface texture than the slopes facing away from the sun
- Granules in the gravel at the base of the downpipes
- Shingles that feel grainy and loose when handled
Why it is scored rather than guessed
How much surface is left decides what a treatment can do, and that is not something you can judge from the ground. The assessment looks at the shingle itself, and the Roof Health Score records what it finds.
A roof with granules still present and asphalt still supple sits in a higher band, where a restorative treatment applies. A roof with the surface largely gone sits lower, where the answer is a bridge or a replacement.
What treatment can and cannot do
It cannot put granules back. What it can do is work into the asphalt that remains, so the surface sheds water again and keeps the flexibility it was made with, which slows the loss that is still to come.
On a roof where the surface has already gone, that is not on offer, and the honest answer is the band the roof actually scored.
What to do next
Note where the granules are collecting and whether the gutters fill faster than they used to. Then have the roof scored, because the score is what separates a roof worth treating from one that is past it.
The assessment is free and it ends with a written estimate rather than a sales conversation.