Tyvek® HomeWrap® and the ZIP System® are weather resistant barriers (WRB) applied under the siding of a home or commercial building. The goal of both these products is to ensure a structure is air- and moisture-resistant. Proper installation and integration are essential to attaining this goal. However, achievement of this goal is also dependent on the WRBs permeability, so water that penetrates the system can evaporate. Also, the WRB must have excellent strength and durability to minimize damage from outside elements (sun, wind, rain) or rough handling during the installation process. Damage to the WRB dramatically diminishes its performance.
While both Tyvek® HomeWrap® and the ZIP System® provide air- and moisture-resistance, each has potential problems that may diminish their intended purpose. A better solution to a WRB is Barricade® Building Wrap. Barricade® Building Wrap is strong, durable, permeable, and easy to install. It will also maintain its integrity against outside elements and rough handling before, during, and after installation.
ZIP System vs Tyvek
Tyvek® HomeWrap® is made from non-perforated, non-woven, high-density polyethylene fibers that are fused together to form a uniform web. The web creates small pores that resist water and air penetration while allowing vapor to pass through. Tyvek® HomeWrap® is equivalent to a Grade-D 60 minute WRB. DuPont™ manufactures the Tyvek® HomeWrap®.
Advantages of Tyvek® House Wrap
A benefit of Tyvek® is it comes in rolls which overlap at the seams to protect the structure from water intrusion. The further advantage of Tyvek® is it allows for weatherboard lap (external cladding) at window heads and other openings in a structure. Another benefit is installation of Tyvek® is over the open stud framing and sheathing, which saves on material costs.
Disadvantages of Tyvek® House Wrap
There are several problems with Tyvek® House Wrap that diminish its ability to resist water and air.
– Tyvek® House Wrap has a tensile strength of only 30/30 lb/in. So, after installation, but before the exterior cladding and final fasteners, Tyvek® House Wrap may be susceptible to damage due to high winds and moisture exposure.
– Similarly, Tyvek® House Wrap has a UV rating of four months. After four months of exposure to UV rays, the wrap may become damaged.
– Tyvek® House Wrap may have a reverse lap, which can trap water. A reverse lap occurs when the horizontal seams are sealed with tape to reduce air leakage. Unfortunately, this can cause water running down the paper face of the upper sheet to flow behind the lower sheet, where the moisture becomes trapped.
The ZIP System®
The ZIP System® includes Zip System® sheathing panels and Zip System® tape. The panels are composed of OSB wood structural sheathing with a Grade-D 60 minute WRB exterior facer of medium density phenolic-impregnated polymer-modified material. The seam sealing self-adhesive tape is a polyolefin sheet with an acrylic adhesive backing. The ZIP System® is manufactured by Huber Engineered Woods, LLC.
Advantages of ZIP System®
An advantage of the ZIP System®, is that because the WRB is applied to the Zip System panels at the factory, installation at the job site should be quick. Also, the Zip System is resistant to wind damage. A third benefit is the product comes with a 30-year warranty, although it has some constraints.
Disadvantages of ZIP System®
There are several problems with the Zip System® that diminish its water- and air-resistance and its warranty advantage.
– During installation, the Zip System® sheathing panels are butted together with a ⅛ inch gap between the panels. Seam tape is used to cover the gap. The tape is used to flash windows and other openings in the home or building. Unfortunately, improper tape application creates a path for moisture to enter the wall system. In addition, dirt, dust, and low temperatures (below 20°F) reduce the bonding nature of the tape.
– The Zip System®, application of the WRB to the sheathing occurs at the factory. Consequently, installation of the framing hardware is at times over the WRB. Unfortunately, when water accumulates and runs down the WRB, the hardware installed over the WRB, is more susceptible to corroding than framing hardware installed behind the WRB.
– Construction of ZIP System® Wall Sheathing is with oriented strand board (OSB) structural panels with a resin-impregnated Kraft paper overlay. Therefore, it is prone to absorbing moisture which will damage the panels before installation. Compounding this problem is the ZIP System® has a one perm rating.
– The Zip System® has a UV rating of 3 months. After three months of exposure to UV rays, the system may become damaged.
– The 30 year Zip System® warranty is void for several reasons: if the tape is exposed to dirt, dust, or cold temperatures, if the tape wrinkles after application, and if it is proven that the structure does not conform to all applicable building codes and industry standards. In addition, the 30-year warranty is not transferable.
How Barricade® House Wrap is a Better Solution as a Weather Resistant Barrier
Barricade® House Wrap is a perforated, high-quality, cross-woven polyolefin house wrap that meets and exceeds requirements for 1water- and 2air-resistance. It is also 3permeable. There are several reasons Barricade® Building Wrap a better option for a WRB over the ZIP System® and Tyvek® HomeWrap®.
– Barricade® House Wrap has a tensile strength (ASTM D-5034) of 63.3 lbs/inch MD, 51.4 lbs/inch CD. Tyvek®’s tensile strength is 30 lbs/inch MD, 30 lbs/inch CD, which makes Tyvek® more susceptible to damage from wind, construction errors, etc. than Barricade® Building Wrap.
– Barricade® House Wrap has a UV exposure rating of 12 months. The UV rating for ZIP System® is three months, and Tyvek® is four months. Potential damage due to exposure to the sun’s rays is less for Barricade® Building Wrap than ZIP System® and Tyvek® HomeWrap®.
– Barricade® House Wrap is easy to install because it is semi-transparent, (unlike Tyvek®) and allows a clear view of the studs and sheathing surface during application. Barricade is also easy to handle, lightweight, and comes in many lengths and widths that can fit the needs of any construction project.
– Unlike the Zip System®, the Barricade® House Wrap has superior temperature resistance (AC38 Section 3.3.4: (Cold Mandrel Bend Test) ) which ensures the house wrap won’t crack at low temperatures.
– Barricade® House Wrap has a permeability rating of 10.4 perms; therefore, it is considered vapor permeable. Zip System®, however, has a permeance of only one perm, which means it is susceptible to trapping water within the wall system.
1 Water Resistance of Barricade® House Wrap: Three tests measure a house wrap’s water resistance. The ASTM D779 (boat test), CCMC 07102 (pond test), and AATCC Test Method 127. Barricade® Building Wrap passes all these tests.
2 Air Resistance of Barricade® House Wrap: House wraps must have high levels of air resistance. Barricade® Building Wrap is an air barrier material in accordance with IRC Section N1102.4.1 and IECC Section 402.4 and 502.4
3 Barricade® House Wrap is permeable to vapor. The ASTM E96 standard, in fact, mandates house wrap with five perms or more. The greater the number, the more permeable the material. Barricade® Building Wrap has a 10.4 US perm rating.