I recently found mold behind the wainscoting in my dining room on the sheetrock below a bay window. I thought the mold might be coming from condensation from the window. After further searching, I found that behind the sheetrock and the insulation, that the foamboard on the outside of the studs just below the window had wide gaps just on the 45 degree corners of the window. Then I found out that the mortar joints on the brick where these gaps were needed repairing because moisture was getting in through the mortar joints, through the gaps in the foamboard causing my problem. I used that foam expanding product called Great Stuff to fill the gaps in the foamboard because it says it is water proof. I am going to repair the mortar joints to fix that problem. I was wondering once I install the new insulation, would it be a good idea to maybe put up some poly film as extra protection. I also plan to use that mold and moisture resistant drywall (DensArmour sp?) this time. Please help.