Why commission the building enclosure?

A crucial part of the BECx plan, to be implemented once construction has begun, is building envelope-related QA observations. The QA observations should not be confused with the day-to-day QC efforts of the general contractor. Rather, the QA observations serve as an objective, extra set of eyes on the project. Unfettered by concerns over liability, cost, or schedule, the BECx site observations are
able to focus on ensuring the building enclosure is being constructed in a way that meets the OPR, the requirements of the construction documents,
the industry standards of care, and the individual product manufacturer’s requirements. The BECx professional does not have authority during the design or construction of a building.  Rather, the BECx team provides recommendations for the designers and contractors to consider. The purpose of those recommendations is to reduce risk and to improve the performance of the building enclosure.

As in the design review, an experienced QA observer brings additional benefits to the project. The experienced QA observer will not only look at what has been accomplished prior to the day of the site visit, but they will look forward at the next steps in the construction process in an effort to eliminate potential problems or issues before they occur. The QA observations also provide an opportunity to identify areas of concern that were not addressed by the design documents, and the observer can help the contractor to communicate those concerns with the DOR.

Although the QA and QC programs are fundamental parts of verifying the construction, there is simply no substitute for field performance testing. What good is it to have a material, or system, that functions well in a laboratory environment, but fails to perform when installed by construction workers at the project site? Field workers may be dealing with a difficult environment, potentially facing extreme heat or cold, rain, dust, and damage from other trades. In addition, some installers may have both limited training and a limited understanding of how their work is supposed to integrate with the materials and systems of others. With this in mind, the only means of ensuring the installed materials and systems perform as intended is to test them.

There are numerous building enclosure test protocols available from ASTM International, the American Architectural Metal Association (AAMA), Factory Mutual (FM) Global, and others. The following are some of the commonly specified and utilized field performance tests:

• ASTM C1153, Standard Practice for Location of Wet Insulation in Roofing Systems Using Infrared Imaging (understanding the use of infrared equipment and the implementation of infrared scanning techniques is required, and core samples of the scanned roof are also necessary.)
• ASTM E2128, Standard Guide
  for Evaluating Water Leakage of Building Walls
• ASTM E783, Standard Test Method for Field Measurement of Air Leakage Through Installed Exterior Windows and Doors
• ASTM E1105, Standard Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Skylights, Doors, and Curtain Walls, by Uniform or Cyclic Static Air Pressure Difference
• ASTM D4263, Standard Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method (This a low-tech, “old school” method.)
• ASTM F1689, Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride
• ASTM F2170, Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes (This test can be a bit destructive, but gives clear results at the site.)
• AAMA 501.1, Standard Test Method for Water Penetration of Windows, Curtain Walls and Doors Using Dynamic Pressure (This a really cool test if you happen to have an airplane engine mounted to a trailer for field testing, otherwise this is typically used for off-site mock-ups.)
• AAMA 501.2, Quality Assurance and Diagnostic Water Leakage Field Check of Installed Storefronts, Curtain Walls and Sloped Glazing Systems (This test is not intended for operable items.)
• AAMA 502, Voluntary Specification
  for Field Testing of Newly Installed Fenestration Products
• AAMA 511, Voluntary Guideline for Forensic Water Penetration Testing of Fenestration Products.

When construction is complete
The BECx process does not end when the building is complete. As we design and build increasingly complex buildings, it is imperative the people responsible for operating the building are properly trained. The end user needs more than just operation and maintenance manuals. They need to understand what was expected from the building (OPR), what was used during construction (BOD), how to troubleshoot the systems if they are not performing as expected or desired, what to do (or not to do) if an issue arises, and who to call for help.

A few months before the contractor’s warranty expires (typically about nine months after substantial completion), the Cx teams should return to the building to see how the structure has performed, what problems were discovered,  and what needs to be adjusted or repaired.

According to an ASHRAE article published in 2008, there are roughly $10 billion in construction defect claims each year, and 69 percent of those claims are related to water infiltrating a building from the exterior environment (i.e. failures of the building enclosure), 53 percent are related to faulty installation, and about 19 percent are attributable to faulty designs (note the percentages cited for design and installation included building enclosure-related components as well as other building components).⁴ This author had multiple conversations in 2016 with providers of insurance for architects, engineers, and contractors related to the more common source of construction defect insurance claims. The conversations indicated these percentages have remained relatively consistent since the ASHRAE report was published. It is clear the designers and constructors continue to struggle with the building enclosure. From the development of the OPR through the training of the end user, a thorough BECx program is a good way to reduce these frustrating and costly mistakes.

Notes
¹ See “Preventing Defect Claims in Hot, Humid Climates,” K. Grosskopf, P. Oppenheim, and T. Brennan,  ASHRAE Journal, July 2008.
² These publications include ASTM E2947, Standard Guide for Building Enclosure Commissioning, which is a replacement for National Institute of Building Sciences (NIBS) Guideline 3, Building Enclosure Commissioning Process BECx; American National Standards Institute (ANSI)/ASHRAE/Illuminating Engineering Society (IES) Standard 202, Commissioning Process for Buildings and Systems; and ASTM E2813, Standard Practice for Building Enclosure Commissioning.
³ One example of hygrothermal modeling software was developed by the Department of Hygrothermics at Fraunhofer IBP.
⁴ See Note 1.

Mickey D. Parker, PE, is practice area leader, building sciences, with Rimkus Building Consultants. Parker has broad experience in all aspects of contract negotiation, planning, design, and construction. His work focused on performing forensic evaluations of buildings, preparing structural engineering designs, providing roofing consultant services, and providing building envelope consulting services. He has been involved in projects including agricultural, single-family, multifamily, commercial, retail, medical, hospitality, assembly, industrial, emergency services, and military facilities. He possesses a BS in civil engineering. He can be reached at mparker@rimkusbc.com.