Nail Sealability ASTM D1970
How well are your membranes sealing around your nails?
A test called ASTM D1970, Section 8.9, is conducted by manufacturers to confirm that their membranes meet a waterproofing standard. The test is administered by covering a piece of plywood with membrane, driving two nails into it, and backing them up a quarter of an inch. The bottom is cut out of a one gallon paint can, and it is sealed with silicone around the two nails. Five inches of water is added to the can, and it is left for three days at 40°F.
Nail Sealability ASTM D1970 is supposed to tell us which products meet a standard of waterproofing, but when the experiment was replicated, the results revealed that even though many manufacturers state that they pass the test, all failed but one.
Passing the test with relatively thin membranes is, to a large degree, dependent on the lab technician. A fastener applied in a perfectly perpendicular fashion has a much higher likelihood to pass the test. In the field this correct application is hardly going to happen when regular contractors apply the fasteners. The problem is that oftentimes the people who get involved in the decision process on which product to use are not familiar with the test procedure and may simply take the word “pass” as a “nothing to be concerned about.”
Even though DELTA®-VENT SA passed the ASTM-D 1970 test, you must realize that any penetration of a membrane poses a potential problem. We recommend to use a patch of DELTA-Flexxband at some fastener penetrations, for instance for brick ties. You cannot assume that when the installer says “no problem” because a membrane passed the test, that there will be no problem in the future.
The conclusion: Depending on the given circumstances wall membranes may not necessarily self-seal around nail penetrations when penetrated by fasteners. An engineered rainscreen, like DELTA®-DRY, will provide drainage and ventilation to ensure that the water that does get behind cladding will drain and dry out. Where penetrations through the water-resistive barrier membrane allow for leakage, a rainscreen is an effective way to ensure that the leaks that do occur will dry out.
Dörken delivers innovative, high-performance air and moisture barriers for commercial and residential construction sold under the DELTA® brand name. A North American manufacturer based out of Beamsville, Ontario, Dörken Products, Inc. is a subsidiary of Ewald Dörken AG, a leading European developer and manufacturer of waterproofing and drainage products sold worldwide. Dörken is known for delivering premium products while providing educational programs and full technical support. For more information, call 1-888-4DELTA4 (433-5824) or visit www.dorken.com.