The mineral granules that cover a membrane or shingles are not decorative: they protect the underlying asphalt against UV rays and wear. When they come loose and leave the bitumen bare, the covering loses its shield and ages faster.
Common causes
aging and loss of adhesion of the granules, hail impacts, concentrated runoff (under a valley or a vent), repeated foot traffic, or a product at the end of its life. Areas under water flow and the bottoms of slopes often lose their granules first.
Signs to watch for
smooth, darker patches where the bitumen is exposed, granules accumulating in gutters and at the bottom of downspouts, a surface that heats up more, visible thinning of the covering.
Why you should not ignore it
without the protection of the granules, the exposed asphalt dries out and degrades under UV at an accelerated rate. Granule loss is therefore both a sign of wear and a factor that worsens that wear. Its extent helps judge the remaining life of the covering.
What a professional assessment reveals
The granules protect the membrane from UV rays; their loss accelerates its aging and exposes the underlayer. An assessment measures the extent of the degranulation and its effect on watertightness, to place the roof in its life cycle, a key point of a pre-purchase inspection.
On a building, a degranulated membrane at the end of its life represents a major capital item. Boreon documents its condition, its remaining life and the budget to plan for during a roof inspection and expertise, and at the same time checks for the appearance of blisters.
Vous soupconnez ce probleme dans un batiment ?
Une inspection le confirme, le documente et le chiffre, pour decider en connaissance de cause.
Inspection preachat Bilan de sante du batiment (BCA) Demander une soumission
