I'm in the process of replacing windows on the house and a problem has arisen. At some of the old windows, the air gap to the brick wall is filled with mineral wool and foam rubber alternately, while at other windows there is an open air gap. The windows with an open air gap seem to be in better condition than those where the ventilation has been blocked. Which is correct? If, unexpectedly, it should be blocked, can one replace the junk that is there now with sealant foam, or will it become too diffusion-tight?
Best regards, Magnus
