Greasy spots on outside walls

turbo

We had an extension on our house four years ago. The insulation is polystyrene beads in the 'old' part of the house and a lot of these beads were lost during building work. We now have greasy spots on some of the upstairs outside walls. Is this a form of damp?.


Turbo

savemoney

Is it dry the greasy spots?

turbo

Thanks savemoney for your quick reply. The greasy patches don't feel wet but wall is cold. Wiping with water makes no difference. Patches are at different heights, some next to radiators and even on ceiling above window. They are on walls at back of house which gets late evening sun only. Haven't looked in 2 front bedrooms as these are bedrooms belonging to our grown up son and daughter and I never go in their rooms. Heating is on approx 8 hours a day during autumn/winter.

Turbo