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Your ZIP System Wall Sheathing Questions — Answered

5 Min Read April 29, 2021

Depending where you live in the US or Canada, you likely have seen homes, apartments, or other buildings under construction built with what looks like green wall sheathing.

The green sheathing boards are one component of a ZIP System™ Building Enclosure. A combination of ZIP System™ sheathing and ZIP System™ sealing solutions family of products, ZIP System Building Enclosures are streamlining weatherization and air barrier installation through a two-step process for builders and framing crews.

Below are some common questions regarding ZIP System sheathing, tape and liquid flash products.

What are ZIP System sheathing panels made of?

ZIP System wall sheathing panels are made of a high-quality, water-resistant OSB (oriented strand board) that is rated Structural 1 for increased shear capacity. A protective water resistive barrier is integrated into the panel during the panel manufacturing process.

Are ZIP System sheathing panels pressure treated lumber?

No. ZIP System sheathing panels do not go through a chemical, pressure treating process during manufacturing.

What is the difference between the green and brown ZIP System sheathing panels?

Thickness. Green ZIP System sheathing panels are 7/16” and the sienna (brown or red) panels are 1/2” or 5/8” thick.

How long can ZIP System sheathing and tape be exposed to weather?

ZIP System building enclosure products have a 180-day Exposure Rating.

What is a WRB?

A WRB is a water-resistive barrier (or weather-resistive barrier). It is a layer of protection from bulk water intrusion in an exterior wall assembly located between the structural wall panel and cladding system. At least one layer of WRB is required by the building code throughout North America.

Does ZIP System need to be covered with housewrap?

Not in most cases. The integrated protective overlay on the ZIP System sheathing panel along with panel seams flashed with ZIP System flashing tape or ZIP System liquid flash can meet the WRB code requirement and eliminate the need for housewrap as a primary WRB in most circumstances.

Can you install housewrap over ZIP System?

Yes. Some exterior claddings (such as stucco) require multiple WRB layers. ZIP System sheathing and tape counts as one WRB layer, so in assemblies in which an additional WRB layer is required by code or the cladding manufacturer, housewrap or another WRB layer will need to be installed. More information on ZIP System and stucco can be found in the Technical Library.

What fasteners can be used with ZIP System wall sheathing?

Code-recognized fasteners that would typically be used to attach conventional OSB or plywood sheathing panels to the framing are acceptable for use with ZIP System wall sheathing. Screws are not recognized as an acceptable fastener for installing structural sheathing like ZIP System to wood framing.

What about all the fastener holes in the ZIP System panel?

Although some builders like the belt and suspenders approach of covering all the nail heads in the panel field with ZIP System liquid flash, it is not a requirement for the ZIP System warranty. Fasteners that miss the framing or go more than half way through the panel, should be addressed, but, other than these, the vast majority of nail heads should not be an issue.

Is ZIP System an air barrier?

Yes. ZIP System sheathing when combined with ZIP System flashing tape (and/or ZIP System™ liquid flash) form a rigid air barrier and acts as an effective component of a continuous air control layer. In addition, ZIP System flashing products can be used in some details to tie in other components of the air control layer for the building.

How many rolls of ZIP System flashing tape are needed per panel?

On average, one 90’ roll of ZIP System flashing tape can flash the panel seams of six to seven standard 4’x8’ panels on a flat wall, depending on the experience level of the framer.

Are ZIP System sheathing panels a vapor barrier?

No, the integrated protective overlay of a ZIP System wall sheathing panel is permeable to allow for drying to the outside.

What’s the permeability of ZIP System sheathing panels?

The permeability of the entire panel is based on the permeability of the OSB (1-3 perms depending on thickness), while the permeability of the integrated protective overlay alone is 12-16 perms.