Windows and doors are also a source for moisture intrusion. Regardless of the type of window or door, wood, vinyl, aluminum, or plastic, they are a dissimilar surface and require sealing with an approved sealant, a Dow 795 sealant or equal (ASTM C920). When applying sealants, the sill/jamb joints of the windows and the thresholds or the doors are suggested to be sealed. Screens on double hung windows are also a means for moisture to damage the window unit and the EIFS and should be removed and stored if not used. Other moisture intrusion concerns are decks, chimney caps, and all utility penetrations of the EIFS. A rule of thumb is if it penetrates the system or is a dissimilar surface, it is suggested to be sealed with a quality sealant.