Vinyl Window Leaking Inside Wall of Newer Home
Help! I have a 7 year old home with a leaking vinyl window. The inside and the sill are dry. However, somehow water is getting in the wall.
My house is built with modern vinyl windows, OSB, 1" thick styrofoam, and then vinyl siding. The leak started a few months ago and we had to remove the siding, remove the styrofoam, replace the wet OSB, reseal around the windows (we assume it was due to the tape / blueskin around the windows not sealing properly - even though it looked okay). Well now it is better sealed and moisture gets in the wall. With every styorofoam seam blueskinned the moisture is trapped in the wall and now I see the OSB getting wet again. I am confident the water is not getting around the blueskin. I figure it either has to be somehow through the window or mullion, or coming from above in the attic. I went in the attic and the OSB is dry.
Anything else I could check? This has been very frustrating. I just want it fixed beofre my house rots out.
I wonder if it is not simehow the mullion leaking between the two window halves and then leaking out the base of the window in the wall. I know the water damage was centered in below each window.
I had to remove the siding and replace the OSB below both pairs of windows. I am told the vinyl caulking must be leakproof. Also the outside channels / flanges do not look cracked. The drain plugs are not plugged, etc.
Any ideas? Thanks for any help. The damage was primarily centered below the two upper windows, but since that area is finished inside, I see the moisture above and below the basement windows. I think the mullion has a holllow channel on the inside of the house.
I uploaded pictures at Diychatroom: