Sometimes the paper debonds, sometimes it doesn’t. At least with the impregnated or coated paper you stand a chance. The Tyvek loses it’s water repellency due to the surfactants in the stucco. It passes through the Tyvek in vapor form as well as by capillary transport. Water stays in the system, because there is no drainage. Now let us replace the building paper (Tar paper) in a hardcoat stucco application with Tyvek. It seems that the more recently manufactured building papers don’t work as well as the old stuff and that they don’t debond as easily. Water stayed in the system, and the building papers (as well as other things) deteriorated. Papers remained bonded to the hardcoat stucco. “The rotten problem was due in part to the lack of drainage between the hardcoat stucco and the building paper drainage planes. We have seen many builders, contractors and home owners using Tyvek stucco wrap as their only layer of water protection but the question is, should we rely in Tyvek Stucco Wrap as our one and only water resistant barrier specially when used in a three-coats stucco system?īuilding Science Corporation Principal Joseph Lstiburek when tyveck issues developed said: The building paper or Tyvek (water-resistive barrier) acts as a drainage plane, and as the stucco dries, water flows down the building paper and weeps out the bottom of the stucco. Stucco is actually a porous material and is designed to allow the absorption of water. tar paper or any grade D building paper, but now materials such Tyvek Stucco Wrap is been used interconnected with flashings, window, door openings, as well as other penetrations of the building and the installation of a rain screen mat to provide drainage of water to the exterior of the building followed by the installation of metal lath mesh and a 3 coat stucco system. As we all know traditional three-coat stucco is a mix of portland cement, lime and sand, generally installed over some type of sheathing materials such as plywood and more recently OSB (oriented strand board), a water resistant barrier paper is installed over the sheathing by using either nails or galvanized staples, traditionally it has been 15 lb.
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