Proof of pudding is in tasting
as a temporaty measure I have had two screens fitted into secondhand rubber frames...one of which is a brand screen into a good condition second use frame...
after this weeks rubbish rain and wind, I can conclude that both screens are pouring water in...and Im confident that the fit is otherwise good..
therefore I would say that some form of 'seal' IS NEEDED in addition to a second hand frame....
the question of what comprises a new frame remains unanswered for now....