Condensation under window sill

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Hello,
Came up to a problem with my windows. There seems to be metal flashing under window sill that goes outside. Half of the flashing is inside (under windows sill) and half outside. Temperature changes causes condensation and water is not draining properly. Not sure how it was installed as house is 1960 and double windows are at least 20 years old. This causes condensation and im worried it will ruin new oak sills. Is there a way to prevent this? Possibly waterproof screed as DPM?
 

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Can you take a pic showing the whole cill area please. And outside pic of poss.

You could put DPC layer of the metal, so moisture won’t Be transferred. Might be better with a sheet of thin insulation first though, to stop cold bridging.

Something like STS board from Wickes.
 
Condensation requires damp air against cold surface , window board eliminates any air .
 
Flashing outside is in perfect condition. I have applied soudal i sulation foam and seems to be catching moisture only on bare metal. I will insulate the whole void before i stalling the sills and hoping it will solve the moisture. If not then will be replacing them in few years :)
 
Hi, did you find a solution to this. I'm currently insulating my bay window and building a window box but I've encountered the same problem I've woke up this morning to find drops of condensation the full length of the flashing
 
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