We suffer with bad condensation on our windows and plasterwork around them. I have just been in the loft and found that the roof is covered in condensation. It appears the roof consists of a plastic sheet with the roof tiles / slates behind this. The plastic is wet and has water dripping from it. Pics attached.
I was planning on insulating the gaps between joist with fibreglass but worried it will just get damp. Will the fibreglass keep heat in and prevent the condensation or does anyone any other advice ot tips?