Do I still need a housewrap or building paper when using Applegate?
When an insulator combines air seal (caulk or foam) with cellulose wall-spray, housewrap or building paper is not needed to control air movement through the wall. However, this does not at all affect the second purpose that a housewrap or building paper serves: that of a drainage plane. Consideration should still be given to a drainage plane based on the local climate. Some areas of the country receive so much rain that the sheathing beneath the exterior finish will almost certainly become wet. The climate in some of these regions may offer only limited drying potential. In these areas, a drainage plane (which may be considered a “housewrap” is certainly recommended.
