Major condensation problem

[Magpie16]

Hi just a quick thought from reading. how old are the windows? the gasket on the window may have broken down and gas may be gone from between the two panes of gas causing window to be a thermal bridge and then would make condensation worse than normal.

 

[^woody^]

That's a penetrating damp or thermal bridge problem.

Check external sealant.

Cut the reveal, and insert a DPC up the back of the external wall if there is none already, and then fill it with expanding foam.

 

[linconhawk]

Magpie16 - Windows were all brand new when we was building...

Woody - Windows were put in and sealed with silicon, since then we have recently rendered, so I think all external sealent is good...
When you say cut the reveal... what do you actually mean ? take a hammer and chisel and "smash" the whole reveal out ? after I do that I will have to re dot n dab and plaster and decorate.... ? Or is there a easy / neater way ?

Not sure where you mean to insall the DPC ? or do you mean fit a cavity closer in the cavity ?

Thanks