Let’s take a look at overdriven fasteners and their effect on ZIP System sheathing.
Nails or other code-recognized fasteners used to attach ZIP system sheathing to supporting framing members may occasionally penetrate beyond the face of the ZIP System panels. In this tutorial, you will learn:
- The definition of an overdriven fastener.
- How the water-resistance and shear capacity of the panels are affected by overdriven fasteners.
- Any effects this may have on the ZIP System 30-year limited system warranty.
What is an overdriven fastener?
An ideal installation would be where fastener heads are flush with the panel surface. However, we recognize that due to variations in materials and limitations on equipment, this may be difficult to achieve in some situations.
Overdriven fasteners: fasteners that are installed through the panel and into a framing member (like a stud or a rafter) with the fastener head penetrating the integrated moisture barrier.
ZIP System sheathing is code-recognized in ICC-ES ESR 1473, has a combination roof-sheathing and roof underlayment. In ESR 1474, ZIP System sheathing is recognized as a combination wall sheathing, air barrier and water-resistive barrier.
One of the tests required of both systems by ICC-ES was ASTM E331, standard test method for water penetration of exterior windows, skylights, doors, and curtain walls by uniform, static air pressure difference.
No visible water leakage at nail penetrations was observed during this test. We have also used this test to verify that overdriven fasteners DO NOT compromise the water resistance of the system.
But I should tape over them anyway, right?
It is not required to tape over overdriven fasteners unless the fastener head creates a hole all the way through the panel. Fasteners that have blown through the entire thickness of the sheathing panel, leaving a hole, are not considered viable and should be taped over with ZIP System tape.
ZIP System panels that are attached with overdriven fasteners will not void the 30-year ZIP System warranty.
Overdriving nails in Zip panels has the same structural effect as regular OSB
Although overdriving a fastener does not affect ZIP System sheathings’ ability to resist moisture, it may reduce the shear capacity of the fastener. Overdriven fasteners can reduce the amount of wind or earthquake loading a shear wall is designed to resist.
This possible reduction in shear capacity is inherent with all diaphragms and shear walls constructed with structural OSB or plywood and is NOT specific to ZIP System sheathing.
More Information on ZIP System:
Please refer to technical bulletins published by APA and TECO at www.apawood.org and www.tecotested.com for more information about reduced shear capacity due to overdriven fasteners. Consult your local building jurisdiction or design professional for any additional nailing that may be required due to overdriven fasteners.
—This video is provided by ZIP System®, one of ProTradeCraft’s advertisers. A next-generation exterior roof and wall solution, ZIP System streamlines the weatherization process with an integrated water-resistive barrier and taped seams replacing the need for house wrap or felt, while eliminating the risk of trapped water between sheathing and barrier and protecting against air leakage. View all Zip System's content