damp concrete floor ?

[benpost]

ever since i bought my maisonette i have had problems with mould appearing on the outside corner walls and along the ceiling edge. as far as i could tell it was just condensation and lack of ventilation causing damp then mould.

yesterday i took up the carpet in the bedroom and noticed the underlay had some darker patches, which upon inspection were wet. underneath the underlay is the original thin lino type tiles which i'm sure were there from when the flat was new.

so i reckon somehow damp has saturated the underlay and carpet and whenever the heating is on its evaporating into the room, ending up on the walls and ceiling. this would make sense and explain the mould growth which has seemed excessive.

so i'm asking anyone here what would my next step be ? how could the damp have soaked the underlay? from the concrete or from the room being cold and moisture drawn to the cold concrete floor? it should all be damp proofed as its part of the flat and not an extension or anything.

[Clot]

Is this room on the northeastern corner of the building? Do you use and heat this room much? Is it collecting much moisture from the bathroom/ kitchen. Is the door to the hall kept open. I'm just wondering if it is acting as the moisture trap. I think my first action would be to get hold of a dehumidifier and try to draw the excess moisture out of the room. Once you have got the humidity down to a reasonable level, then you could try to explore where the moisture is coming from. If the moisture was coming through the floor then the underlay would like continue to get wet whilst the rest of the room *walls( kept comparatively dry.