Source: AXA XL

Curtain walls

A curtain wall is an exterior façade wall system that is attached to a building structure, often serving as a weather  barrier, but is not a structurally load-bearing building component. Demand for increasingly ornate, intricately  designed and energy efficient curtain wall systems in today’s construction market has grown dramatically and can be found on an array of vertical building projects in many of the construction market sectors.

Potential Concerns

• Interface between multiple envelope design components is a potentially unrealized delegated design exposure for a contractor.
• Design errors around the anchoring/ fastening of the curtain wall system to the building.
• Installation quality is a critical determinant of overall curtain wall system performance.
• Increased demand for more intricate curtain wall design, requiring special expertise for installation, with only  a small percentage of experienced installers.
• Aesthetic elements, such as color of the curtain wall, not matching the color specified by owne.
• Increased potential for repetitive errors or defects in each curtain wall unit due to mass manufacturing.
• Performance failures, including water intrusion, condensation, frosting, glare, glass breakage, free fall of wall fragments, glass scratching, corrosion, and aesthetic imperfections of glass and any applied coatings.

Claims

• A hospital project required retrofitting after decorative tiles began falling onto street below. Due to a  manufacturing defect, some of the tiles were cut too short and did not anchor properly to the structure.
• Property damage resulted when sun-blocking film on spandrel glass units of a mixed-use residential project  began peeling away from the glass units.
• An innovatively designed cable system for a cable net wall at a commercial building could not maintain the  specified tension on the cables, due to building movement, resulting in shattered glass panes.
• Curved aluminum panels on a building at a university were a different color than the flat aluminum panels, requiring recoating, re-assembly, and reinstallation.
• The glass panels on a commercial project had a tint that was not specified in the contract and was different from the mock-up, resulting in a claim.

Action Items

• Perform repeat testing of materials and mock-up testing of units in different elements (i.e., sun, wind, rain)  prior to installation to ensure successful performance and sufficient design calculations.
• Obtain a peer review for intricate designs to evaluate interactions with other building envelope
  materials.
• Perform inspection and routine servicing of curtain  wall sealant layers to avoid chipping, cracking, and/or flaking.
• Define a range of acceptable deviation in the procurement (with manufacturing/ contract documents) with owner or general contractor.
• Implement a quality control procedure at the manufacturing facility and/or as panels arrive to the job site to  ensure panels have been assembled per specifications.
• Use a spectrometer to assist with achieving color desired and specified by the owner for the final finish  required.
• Integrate a water intrusion and mitigation plan throughout the construction team and length of project.
• Ensure that curtain wall subcontractors carry adequate levels of professional/pollution insurance.
• Consider using one of today’s technologies to assist with exterior wall inspections such as DroneUp or DroneDeploy and/or a subcontractor prequalification technology such as Bespoke Metrics or TradeTapp.