Last week a man knocked on our door claiming that he could get us compensation for 'badly done cavity wall insulation done years ago which would cause our home to get damp' . If we had a certificate he could get us a lot of money back. Now whether he was bonafide or scammy or just selling cavity wall insulation i am not sure, but we dont have a certificate for our CWI so we sent him away. It did lead me to thinking about how any damp or degraded Cavity wall insulation would be removed in order to put new sort in???? Does anyone know how it is removed and how you could ever be sure they got it all out especially if it is causing damp?