Sedlbauer, K.K.SedlbauerKrus, M.M.Krus2022-03-032022-03-032002https://publica.fraunhofer.de/handle/publica/20256210.1177/0075424202026002782On the external facades of a housing project, which was completed in autumn, a noticeable biological growth appeared after a short time. Especially in the area of the lintels an extended mold infestation could be seen (obvious discolouration). The lintels have not been insulated with expanded polystyrene like the rest of the walls, but with mineral wool. Also mainly circular patterns of the infestation appeared in the middle of the fac¸ades. Drill core samples were taken in these places. It turned out that the insulation slabs of expanded polystyrene had not been applied without joints, but that a continuous gap of approximately three millimetres existed between the insulation sheets. The circular patterns of mold infestation are approximately located in the area of the joint crosses where four insulation slabs meet. It is assumed that a moistening mechanism takes effect which has already been analysed and documented in connection with the danger of frost damage ("Diffusion moistening"). This diffusion moistening is immediately linked to the high vapour transmission factor of the mineral wool insulation and with the air gaps between the insulation slabs.en624690614696journal article