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August 8, 2016
- Design & Construction
By Daniel Delisle Many new and existing buildings do not perform as anticipated due to problems with the design or construction of the building envelope. Air infiltration and exfiltration, along with unmitigated heat transfer, can lead to poor energy performance and other adverse issues. Water penetration in the form of moisture-laden air or bulk water is one of the biggest problems — surprisingly, almost every building leaks at some point during its service life — often resulting in costly damage to interior building materials. The issues that result from inadequate integration and continuity of water, air, and thermal barriers also increase ongoing operational, maintenance, and repair costs. At the very least, these problems may result in occupant discomfort and tenant dissatisfaction; at their worst, they may raise liability risks for the owner.A building enclosure consultant contributes specialized engineering knowledge for the effective integration and continuity of air, water, and thermal barriers for below and above-grade structures, including exterior cladding systems, fenestration, and roofing systems. Depending on the type of project, building enclosure consulting services may benefit the architect, contractor, property owner/manager, developer, and insurance company, or construction law firm.Technically, the building enclosure consists of the sum of the physical barriers between the exterior and interior environments or, more precisely, between the unconditioned outside atmosphere and the conditioned and controlled indoor space. Practically, the building enclosure consists of the components of the exterior “envelope” or “skin”: foundations, slabs, basements, plaza decks, balconies, wall systems, storefronts, curtain walls, doors, windows, and roofs.
As a member of a project team for new construction, a building enclosure consultant offers engineering insights and services that help the team achieve a number of important objectives:• Avoid design problems prior to construction.• Propose the most appropriate selection of materials.• Ensure unified and continuous integration of building enclosure systems. • Synchronize project design and construction phase documents.• Provide support for construction coordination of envelope trades.• Minimize construction delays due to unanticipated issues. • Assist with required functional performance testing for envelope systems and mock-ups.• Assist in resolving field condition issues during construction. Schematic Design (SD) phase. During SD, the consultant typically focuses on the major build-ing enclosure systems and materials, offering the project team recommendations about the systems and manufacturers under consideration for the building enclosure. These include the materials and interface details for below-grade, fenestration, facade cladding, and roofing systems. The consultant helps the project team to work through the design concepts, providing detail sketches for the team to consider incorporating into design drawings.Design Development (DD) phase. During DD, the project team typically uses the consultant’s input to compare interface detail options. Mark-ups and written comments on the development drawings include specific recommendations and design detail concepts, such as refinement of flashing and system integration details. The consultant also reviews technical specifications and the testing and inspection procedures for each major building enclosure system. Construction Documents (CD) phase. During CD, reviews of drawings and technical specifications help the team to further refine the integration of interface detailing and the selected enclosure systems. A thorough review and commentary of each enclosure-related technical specification section covering provisions and requirements is provided and intended to improve the performance and implementation of the prescribed work. Modeling studies inform design. During the design phase, the consultant can also perform modeling studies that improve design of the building enclosure systems. For instance, a hygrothermal analysis early in the design phase can be used to assess moisture movement in wall and roof assemblies and the potential for condensation and moisture accumulation. Similarly, the results of heat transfer modeling assist the project team in examining various products for thermal performance and their framing and tie-ins to the rest of the enclosure. Construction phase. During construction, the consultant’s continued oversight — including shop drawing reviews, participation in pre-construction/kick-off meetings, mock-up development, performance testing, and construction observations — assists the team in validating that building enclosure construction and performance objectives have been achieved. Based on a visual survey or physical testing, the consultant reviews material installation requirements against industry standards for level of craft and care, checking for the appropriate use of each building envelope component for continuity and effective engagement and termination into adjacent systems and accessories. A site visit report generally follows construction phase services and typically includes a photographic record, summary of observations and findings, and recommendations for repair or replacement of components as needed. Further, the consultant can observe or direct the performance testing of roofing, cladding, and fenestration (e.g., water penetration and air infiltration testing per ASTM, AAMA) to validate compliance with current industry standards.
Post-occupancy, and for aging and historic buildings, a building enclosure consultant can provide property condition assessment services and associated opinion/documentation in the form of property condition reports (PCR) or Forward Maintenance Register documents. The PCR may include observed concerns, recommendations for repairs or further inspections, and planned expenditure of compiled assets. An exterior envelope condition survey is typically performed with detailed surveys of other systems, including MEP, structural, environmental, lighting, building, fire and life safety, and lift/escalator systems. When air, water, or thermal issues are identified in an existing building — either as a result of defects in construction, incompatible systems and materials, or normal wear and tear — a consultant can perform the appropriate forensic analyses to verify the cause and extent of damage. These insights are important not only to support warranty claims, but also to develop an effective remediation solution.To help prevent problems arising from inadequate integration and continuity of the building enclosure systems during design and construction, to improve building performance, to enhance occupant comfort and tenant satisfaction for the life of an existing building, and to investigate and analyze your existing, aging, and historic buildings, consider engaging a building enclosure consultant. Daniel Delisle, PE, LEED AP, is an associate, building enclosures, in the Los Angeles office of WSP | Parsons Brinckerhoff. Delisle has worked throughout the United States on a wide range of building enclosure projects. Delisle brings over 15 years of experience to the building enclosures team on a wide range of projects, including museums, high-performance buildings, sustainable design projects, schools, residential and mixed use projects, parking structures, hospitals, and green roofs.