Testing for Quality: The Performance Mock Up

The KA Block, Oct. 24, 2016. H.Q. Apartments construction is on the right

Looks are not everything, in life or in construction. Performance counts. Construction management teams work closely with owners, designers, engineers, subcontractors and testing resources to confirm that buildings meet expectations for energy use, safety, security, mechanical equipment commissioning and weather resistance.

Quality assurance can include constructing and testing building methods and materials in a laboratory setting to identify and correct vulnerabilities before they reach the jobsite.

Vertical construction of H.Q., the KA Block’s 17-story apartment tower, was underway in downtown Minneapolis. To evaluate the building methods and materials for appearance and performance, the project team built a full-scale replica of the 16th-floor exterior wall and tested it in a laboratory environment under extreme weather conditions. Watch the test.

What Is the Purpose of Mock Wall Testing?

Jon Porter, Kraus-Anderson Quality Manager: A Performance Mock Up, or PMU, validates the performance of an exterior wall assembly, including air-tightness, water-tightness and resistance to wind loads. It also helps evaluate design, workmanship and material selection while gaining approval from clients, architects, contractors and consultants.

A PMU can help the project team identify potential deficiencies in the design, fabrication and installation of a wall system before the system is put into use.

The concept is similar to trying a recipe before preparing it for a large dinner gathering. It is often helpful to create a trial batch before committing to the larger effort.

H.Q. Apartments would have more than 120,000 square feet of wall surface exposed to wind, rain and seasonal temperature and humidity changes. The 500-square-foot mockup provided a trial run to help the team understand how the wall system would perform.

What Portion of the Building Did the Mock Wall Simulate?

Porter: The PMU closely approximated the west-facing exterior wall condition at the 16th floor of the H.Q. apartment building.

Rendering of H.Q. Apartments

Why Was the West Wall Chosen for Replication and Testing?

Porter: The west wall overlooked a courtyard and included exterior balcony doors in the same plane as the exterior wall, with balconies extending outward. That condition created greater exposure to the elements.

Where Was the Mockup Wall Created?

Porter: It was built at ATI, Architectural Testing, Inc., in Saint Paul.

How Large Was the Mockup Wall?

Porter: The wall measured 37 feet long by 13 feet, 6 inches high.

Who Worked Together to Design and Engineer the Mockup?

Porter: The PMU was a joint effort among multiple subcontractors and Kraus-Anderson. It simulated the wall design provided by ESG Architects and MBJ Structural Engineers.

ATI provided the five-sided test chamber, with the mockup forming the sixth side. Subcontractor partners engineered specific elements within the wall section, including steel studs, aluminum framing systems and fiberglass windows.

  • ATI provided the basic test chamber layout.
  • Olympic Companies installed steel studs and polyiso sheathing.
  • Braxton installed wood blocking around wall openings.
  • Crossroads installed the Pella window, which was better suited to locations with lower wind loads.
  • WL Hall installed the aluminum-framed opening and patio terrace door, which was designed for higher wind loads.

What Materials Were Used in the Wall Construction?

Porter: The wall included steel studs, wood blocking, rigid insulation sheathing, spray-applied and adhered flashing, a mechanical furnace and air-conditioning unit with a wall louver, a combined dryer and bathroom vent, fiberglass and aluminum windows, an aluminum patio door and metal paneling.

Were Mockups Used on the Kraus-Anderson Office Building?

Porter: In addition to small-scale material mockups and samples, the office building had a visual mockup.

Unlike a performance mockup, a visual mockup does not undergo specific testing. It is used primarily for visual review and approval of the finished appearance. A performance mockup was more appropriate for the apartments project because of its exterior wall conditions and project requirements.

How Common Was This Process Within Kraus-Anderson’s Quality Efforts?

Porter: Visual mockups and small-scale material mockups or samples are common and are often required in project specifications. Performance mockups are less common and may occur only once every several years.

Learn more about Building Science services and curtain walls from the contractor’s perspective.

How Were New Energy Code Requirements Incorporated Into the Building?

Porter: To address energy code requirements that took effect in 2015, the project used a wall system that eliminated typical sheathing, such as plywood or gypsum board. It used a combination of rigid insulation board and spray-applied insulation.

The system provided a consistent weather-resistive barrier and air barrier without requiring large areas of sheet material, such as housewrap or poly sheeting, across the full wall surface.

Read more about Minnesota energy code requirements.

Did the Wall Include Different Materials or Methods for Comparison?

Porter: The visual treatment remained consistent. However, minor details in the termination and sealing of the weather barrier varied so the team could study whether certain treatments performed better than others.

What Did the Team Learn From the Performance Testing?

Porter: The original system used a more industrial product typically found on warehouses or distribution centers with large areas of uninterrupted wall. It was not well suited to a building with many windows, doors, vents and louvers.

Based on the testing, the team changed the exterior panel to a higher-quality composite aluminum panel. The revised material provided the needed weather performance, a higher-quality finish and improved appearance, while reducing field labor and installation costs.

What Was the Owner Benefit of Investing in a Mockup Wall Test?

Jaci Bell, Director of Development, Kraus-Anderson Development: A mockup of this scale provided an opportunity to preview materials and installation methods before they were applied across the project.

Testing form and function allowed the team to confirm performance assumptions and identify materials or methods that might not perform as well over time. It also allowed small details to be refined before construction, supporting confidence in the final result.

For the broader project story, read about H.Q. Apartments opening at the KA Block.

CATEGORY: Construction