We have installed new double glazed units in timber windows approximately twelve months ago. We now find that the black bitumine inner seal is melting in blobs on some of the units, could you please tell me if you have come accross this problem before and tell me what may have caused this to happen.
Have a read of this.It's a useful and detailed document on the subject.
It's not a unit fault at all, but a silicone issue. 'neutral cure' or seeing the use of 'glazing' on it isn't a rubber stamp of suitability.. There's so many silicones now full of additives, fillers, anti-fungals etc that cause real damage to DGU's up and down the country.