Nondestructive Field Testing of Installed Weatherproofing Sealant Joints—Questions and Answers

ABSTRACT: With current expectations for building exteriors to prevent all air and water entry into the building interior, the need for a near perfect seal of weatherproofing sealant joints has reached new levels of intensity. The need for better field tests has increased accordingly. To reach these goals, ASTM Standard C-1521-02a [1] has been developed and adopted. The practice outlines a nondestructive procedure. This procedure provides an examiner of the joint the option of inducing an artificial strain to the sealant bead using a blunt instrument so that the sealant is subjected to a stress at the bond line typical to the anticipated cyclic movement endured by the sealant during the normal service life of the joint. The advantage of this methodology is that it allows an unlimited amount of testing to be conducted. While the procedure does not specify a specific instrument to induce the strain, a device able to accomplish this procedure in a uniform, controlled, and calibrated fashion has been developed. The paper outlines a description of the device and its capabilities. The paper also provides a discussion of the use of statistical sampling when the option of 100 % testing is not feasible or required. The author believes that the future of field testing of installed weather proofing sealant joints should include enhanced nondestructive procedures. Continued field use, research, and development are essential in the quest for a near perfect building seal.

KEYWORDS: sealant, adhesion, nondestructive, testing device, field testing, toxic mold, ASTM Stan­dard C 1521

Introduction

The following discussion is directed toward barrier wall construction (face sealed) utilizing a single line of sealant joint as the only defense against the exterior climate. For the purpose of this discussion, failures are defined as loss of sealant adhesion. Adhesion failure is easily defined—the sealant either sticks to the joint or it pulls away free and clear. Joint geometry is not as easily defined with a pass/failure criterion, but it is discussed below. While the information provided may be useful in other areas of consideration, the author makes no assertions beyond those stated here. The stated goal of the testing advocated here is to find and fix failures of the sealant with the net result of producing a durable and complete building seal.

The current paper is a follow up to a previous paper by the author [2]. That paper began with the following comment: “A durable building seal requires full and continuous adhesion of the weatherproofing sealant in all joints at all locations.” This comment coincides with the fact that the expectation for building exteriors to prevent all air and water entry into the building interior has reached a new level of intensity. In the case of toxic mold litigation, it has simply become too costly to expect anything less. It is the intent of this paper and the research it shares to assist the industry in achieving this goal. To that end, ASTM committee C-24 has taken the step of adopting ASTM Standard C-1521-02a, “Standard Practice for Evaluating Installed Weatherproofing Sealant Joints” [1].

The standard advocates a nondestructive procedure that provides the examiner of the joint the option of inducing an artificial strain to the sealant bead using a blunt instrument so that the sealant is subjected to stress at the bond line typical to that produced during the cyclic movement of the joint during normal service life (ASTM Standard C-1521 at 1.4, 6.1, and 7.1.2). This procedure validates the previously conceptual testing method of application of external pressure to the installed weatherproofing sealant joint.

The advantage of nondestructive testing is obvious; the quantity of sealant joint available for test is limited only by the needs of the specifying authority and access to the joint. A device able to accomplish

Manuscript received May 3, 2005; accepted for publication May 16, 2006; published online August 2006. Presented at ASTM Symposium on Durability of Building and Construction Sealants and Adhesives, Second Symposium on 15-16 June 2005 in Reno, NV; A. T. Wolf, Guest Editor.

1 Associate Consultant, Construction Consulting Laboratory, 4751 West State Street, Suite B. Ontario, California 91762.

Copyright © 2006 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohoeken, PA 19428-2959.

FIG. 1—Photo of pressure-controlled inspection device.

this nondestructive procedure in a uniform, controlled, and calibrated fashion has been developed. The paper outlines a description of the device and its capabilities and provides a discussion of the use of statistical sampling when the option of 100 % testing is not feasible or required.