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Cx Monitor: Effective Use of Building Enclosure Mock-ups within the Commissioning Process

The building enclosure (envelope, skin, etc.) represents one of the highest risk elements of construction. Water intrusion, air leakage, and increased energy consumption are common consequences of poorly designed and constructed building enclosure systems.  An effective building enclosure commissioning (BECx) and testing program can reduce these risks along with associated long term effects such as mold or poor indoor air quality.

By definition, BECx is a quality-based process implemented to evaluate and verify the owner’s project requirements throughout design and construction. A critical step in the BECx process is the mock-up phase, which is often not implemented effectively on new construction projects. This article will summarize building enclosure testing and provide guidelines on how mock-ups can be fully utilized on any project.

Types of Building Enclosure Testing

There are three primary categories of building enclosure testing: product laboratory testing, project mock-up testing, and field testing. Each form of testing is briefly summarized below:

When a product is developed by a manufacturer, it undergoes testing in a laboratory setting, primarily to meet the performance/certification criteria located in Part 2 of project specifications. The better the test results and more certifications a product can achieve, the more marketable it is. Specified requirements, and therefore the required testing, can be comprehensive. Product testing is dependent on the type of product and can include a broad range of testing, from structural to air permeance to water penetration.

Mock-up testing is performed as part of a project specific test plan and focuses on the installed building enclosure assemblies. While mock-up testing will verify that the individual systems are assembled and installed appropriately, its focus is to ensure that all systems will function interactively to meet the project goals. The testing conducted is typically not as comprehensive as laboratory testing, but can include structural, seismic, thermal, durability, air infiltration, and water penetration.

Field testing is conducted on the building at intervals during construction, after the installed components are complete. The types of field testing are similar to mock-up testing, although typically not as comprehensive. Traditionally, field testing has focused on air infiltration, water penetration, and durability testing. On successful projects, field testing is verification with passed test results, not trouble-shooting to determine the causes of failures.

Mock-up Implementation Guidelines

Depending on the project budget, complexity, and owner’s project requirements, either a laboratory or on-site, stand alone mock-up can be utilized. It is challenging to conduct testing beyond air and water (e.g. structural, seismic, thermal, etc.) with on-site mock-ups, and this should be considered during program development.

In general, the following guidelines should be considered during the mock-up construction and testing phase:

  • The functional performance test requirements, including the mock-up requirements, should be developed by the building enclosure commissioning agent (BECxA), reviewed/approved by the Architect of Record, and inserted into the project specifications via a stand-alone specification section within Division 01.
  • The testing program must be project specific, designed to verify the owner’s project requirements, and best simulate the anticipated environmental conditions at the project location.
  • All typical project details, critical interfaces, and high risk conditions should be considered for inclusion on the mock-up.
  • The mock-up configuration should be designed and constructed as a full enclosure that will easily facilitate the specified testing.
  • Testing and inspection must be conducted prior to installation of any claddings or interior finishes not responsible for environmental separation.  All fastener penetrations (e.g. masonry anchors, girts, etc.) and other penetrations through the air/water barriers should be installed prior to testing.
  • Successful mock-up testing and acceptance must be achieved prior to installation of any enclosure systems on the building.

A fully leveraged BECx and mock-up testing program can improve quality, control risk, and minimize costly changes and delays during construction. The upfront cost and time associated with a mock-up is typically significantly less than repairing problems that occur after building completion. Any questions about your project or mock-up can be directed to Rick Ziegler at 615-420-0360 or