Bitumen bleed (or bleeding) occurs when the asphalt of a membrane or shingles rises and beads at the surface under the effect of heat, forming shiny black runs or patches. It is a sign of the aging and thermal stress of the covering.
Common causes
intense heat and sun exposure, aging of the asphalt as it loses its oils and reconfigures, overheating of a poorly ventilated roof, or a lower-quality product. The phenomenon is seen mostly on older roofs and dark, highly exposed surfaces.
Signs to watch for
shiny black runs or stains on the surface, softening of the covering in hot weather, granule loss in the affected areas, bitumen accumulating at low points or in gutters.
Why you should not ignore it
bleed frequently accompanies the end-of-life phase of a covering: asphalt that sweats is asphalt that is drying out and losing its flexibility, foreshadowing a loss of watertightness to come. It is a useful clue for placing the roof in its life cycle and anticipating its replacement.
What a professional assessment reveals
Bitumen bleed often signals a roof at the end of its cycle or subjected to excessive heat. An assessment places the phenomenon within the overall condition of the covering and estimates the remaining useful life, useful information from a pre-purchase inspection.
Bitumen bleed betrays advanced aging of the membrane. Boreon assesses it as part of a roof inspection, in relation to the overall condition of the membrane.
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