Tyvek FAQ
Top 1. When a building is mostly glazing, why use a building wrap?DuPont™ Tyvek® should be considered for its ability to help manage air, water and moisture in a building's wall system. Water inevitably finds its way inside walls, whatever the cladding. Unlike building papers, DuPont™ Tyvek®, properly installed, has a combination of properties that can protect wall systems and improve energy costs. DuPont™ Tyvek® works together with insulated glazing to help reduce air infiltration, fostering more efficient HVAC operation, and potentially lower maintenance costs. 2. What is the flammability of DuPont™ Tyvek®?DuPont™ Tyvek® is combustible and should be protected from a flame and other high heat sources. If the temperature of DuPont™ Tyvek® reaches 750° F (400° C), it will burn and the fire may spread and fall away from the point of ignition. For more information call 1-800-44-TYVEK. DuPont™ Tyvek® carries a Class I or NFPA Class A fire rating for flame spread and smoke developed index as measured by ASTM E-84. Top3. How long can DuPont™ Tyvek® be exposed before siding?DuPont™ Tyvek® StuccoWrap® should be covered within 120 days (4 months). 4. Can you use DuPont™ Tyvek® in combination with a vapor barrier?Using a vapor barrier depends on how the rest of the wall system is built and the climate the wall is in. If the majority of the year is spent heating the home where the inside temperature is greater than the outside, it is generally good to use a vapor retarder behind the interior drywall. In hot humid climates, vapor barriers should not be used. 5. Is DuPont™ Tyvek® a vapor barrier?No, DuPont™ Tyvek® is not a vapor barrier. It is breathable, allowing moisture vapor to pass through it. Top6. Should DuPont™ Tyvek® be placed over or under the sheathing?DuPont™ Tyvek® can be used either over or under sheathing. When DuPont™ Tyvek® is used under sheathing, it functions only as an air barrier and does not protect the sheathing as a secondary water barrier. DuPont™ Tyvek® has been used directly over studs where there is no sheathing, although use of sheathing is a highly recommended building practice. 7. What is the difference between DuPont™ Tyvek® and black paper?Black paper or building paper was not designed as an air retarder like DuPont™ Tyvek®. Unlike DuPont™ Tyvek®, building paper can absorb water. Building paper tears easier than DuPont™ Tyvek® and can degrade over time when under continual exposure to water. Building papers are less permeable to moisture vapor transfer than DuPont™ Tyvek® increasing the potential moisture vapor trapped inside the wall could cause mold, mildew and rot. 8. What is the difference between DuPont™ Tyvek® and other housewraps?Many other wraps are perforated, which means in order for them to breathe, the manufacturer has punched holes in them, resulting in a reduction of air and water holdout effectiveness. DuPont™ Tyvek® is a non-perforated, nonwoven product with microscopic pores that are so small air and bulk water have a difficult time passing through but since DuPont™ Tyvek® is breathable, moisture vapor can easily escape from the wall. Top9. Can you use DuPont™ Tyvek® under any primary cladding?Yes, DuPont™ Tyvek® can be used under any cladding including brick, stucco, vinyl, cedar siding, and stone. Proper installation under each cladding is essential to ensure DuPont™ Tyvek® provides the maximum level of air infiltration resistance and bulk water holdout. 10. Can DuPont™ Tyvek® be used as flashing?DuPont™ Tyvek® weather resistive barriers have not been tested or approved as a flashing material. DuPont introduced the DuPont™ Flashing System that provides comprehensive protection from water leaks. It is designed to help direct water to the building exterior instead of trapping it inside the wall system and causing water damage. 11. Can DuPont™ Tyvek® be used with the lettering facing in?DuPont™ Tyvek® StuccoWrap® is equally effective in both directions. However, DuPont™ Tyvek® StuccoWrap® has a specially engineered surface that should be placed with the grooves in a vertical direction. Top12. Can I tape sheathing board seams?Taping sheathing board seams creates a continuous vapor barrier, so moisture vapor would have nowhere to escape. Adhesion of tape to foam and wood would also be temporary, due to thermal expansion and contraction of the wall assembly. A more effective and efficient means to provide air infiltration resistance and bulk water holdout is to properly install DuPont™ Tyvek® using our best practice guidelines. Since DuPont™ Tyvek® is flexible, it will continue to provide protection to the sheathing when undergoing thermal expansion and contraction. 13. Why should I tape seams in the DuPont™ Tyvek®?Taping the seams with DuPont™ Tyvek® Tape gives you the best Tyvek®-to-Tyvek® adhesion, optimal protection against air and bulk water penetration, and extra durability protection during the building's construction phase. 14. Is DuPont™ Tyvek® necessary over foam board?DuPont™ Tyvek® adds considerable protection against leaky seams in foam board, similar to the protection provided over wood sheathing. Foam boards alone, even interlocking foam boards, do not adequately stop air leakage due to wall movement from settling and thermal expansion and contraction. Top15. Can I use DuPont™ Tyvek® StuccoWrap® under brick?Yes. It is perfectly acceptable to use DuPont™ Tyvek® StuccoWrap® under brick. When DuPont™ Tyvek® StuccoWrap® under brick it is important to follow brick manufacturer's guidelines regarding the use of an air space between the brick veneer and sheathing. Typically this space is 1"-2" and will act as a drainage plane if incidental moisture were to penetrate the brick in addition to ventilating behind the cladding which aids in drying of the wall assembly. 16. Can DuPont™ Tyvek® be installed vertically instead of horizontally (drop it down from the top?)Although this installation method is not recommended it is important to ensure that if this method is used the vertical seams must overlap by at least 6" and taped with DuPont™ Tyvek® Tape. This will provide the greatest level of air infiltration and bulk water holdout protection. Recommended installation instructions can be located on this website or the roll label affixed to the product. 17. Will duct tape work as well as DuPont™ Tyvek® Tape?No. Duct tape is not designed to be used with DuPont™ Tyvek®. DuPont™ Tyvek® Tape has been specifically designed to work with DuPont™ Tyvek® products and should be used in all situations when sealing of the DuPont™ Tyvek® seams is necessary. Top18. What type of fasteners is recommended when installing DuPont™ Tyvek®?DuPont™ Tyvek® can be installed using a variety of fasteners depending on the application. To attach DuPont™ Tyvek® to wood, insulated sheathing board or exterior gypsum board, use nails with plastic washer heads, such as DuPont™ Tyvek® Wrap Caps. You may choose to use wide staples with a minimum 1" crown. For steel frame construction use DuPont™ Tyvek® Wrap Cap Screws. 19. Can DuPont™ Tyvek® be used under cedar siding?Yes, DuPont™ Tyvek® DrainWrap™ can be used under cedar siding. It is recommended that the cedar siding be installed per manufacturer's guidelines and recommendations by wood siding associations, such as the Western Red Cedar Lumber Association, including priming all surfaces including the back and ends before installing. Additionally, the use of furring strips will help promote drainage of any incidental water that may penetrate the cedar cladding. 20. Can you use DuPont™ Tyvek® under any primary facade?Yes, DuPont™ Tyvek® can be used under any cladding including brick, stucco, vinyl, cedar siding, and stone. Proper installation under each cladding is essential to ensure DuPont™ Tyvek® provides the maximum level of air infiltration resistance and bulk water holdout. Top21. If I caulk seams, why should I use housewrap too?Since most lumber typically has moisture content of 15 to 20%, when the house dries, the moisture content drops. The lumber will shrink slightly and pull away from the caulk, breaking the seal. Over time the caulk's effectiveness is reduced. By using DuPont™ Tyvek® maximum air infiltration resistance and bulk water holdout is maintained since the entire wall assembly is covered in a protective envelope. 22. Doesn't housewrap make a house too tight?With more energy efficient construction, "building tight; ventilating right" is the best practice. Mechanical ventilation is more important with today's sophisticated energy saving home features. However, blower door testing on homes wrapped with DuPont™ Tyvek® show natural air exchange rates per hour that are well within acceptable guidelines per ASHRAE Standard 62. 23. How many rolls of DuPont™ Tyvek® are required for a typical two- story house?For a typical two story, 2500 square foot house, the general rule of thumb is two rolls of DuPont™ Tyvek® size 9' x 150' should be adequate to wrap the house. However, this estimate may vary slightly depending on the house elevation. Top24. Is it necessary to remove old building paper before applying DuPont™ Tyvek®?It is not critical to remove building paper prior to installing DuPont™ Tyvek®. However, it is necessary to carefully inspect for damaged areas that may not be clearly visible under building paper. Since building paper does not have the same breathability characteristics of DuPont™ Tyvek®, the wall may lose some of its ability to dissipate moisture to the outside if the paper is left on the wall. |
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800.937.9021 Ext - 106, Or Vapor Barrier Products
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