Children’s Health Medical Center

Title: Children’s Health Medical Center

Award Category: Commissioning

Project Address/Location

Plano, TX
7601 Preston Rd
Plano, TX 75024
United States

Submitted By: Tamara Higgins

Company Info

Lerch Bates

6300 Fallwater Trail
Suite 120
The Colony, TX 75056
United States

972-955-5187

[email protected]

Project Description and Background: Children’s Health Medical Center in Plano, TX is a four-story, 72-bed, 326k sf Pediatric Specialty Hospital that serves the five-county area of North Dallas. The planned expansion added 140 beds, a new 650-car parking garage, including a 395k sf addition and 60k sf in renovations. This integration of new and existing materials and critical nature of the healthcare space provided unique enclosure-related challenges which demanded a heightened level of attention to detail throughout the design and construction process. The existing building was fully occupied and functional throughout construction, so ensuring the accuracy of connectivity and sequencing was extremely important. The construction team was responsible for limiting any disruptions to the existing hospital space, including opening of walls, roofs and glazing, which would allow the unhealthy construction elements to enter the hospital space. Learning from the existing building's performance, the project lent itself to a full commissioning (Cx) scope, which included building enclosure commissioning (BECx) for the life cycle of the new expansion enclosure to mitigate any potential issues and perform at a higher level, while maintaining the Architect of Record’s (AOR) vision and design intent.

Scope: There are always risks associated with improper envelope design and/or construction that may result in bulk water intrusion, widespread condensation, pressure equalization issues, and disruption to operations. Once installed, these systems are inherently difficult and expensive to repair, which further compounds the need for proper installation prior to turnover. Building envelope commissioning (BECx) is a complex and multi-faceted process that requires active involvement from ownership, design professionals, the general contractor, CxA, and all subcontractors involved with constructing or penetrating through the building envelope. As a Building Enclosure Consultant, our approach revolves around early collaboration whereby all affected parties understand project goals and expectations, the sequence of frequency of events, and their responsibilities in the process. Our focus remained consistent on quality amongst all interested parties, and we had a shared commitment to delivering a high-performing building enclosure system. The scope of work that we performed as the projects BECxA/P included: • Review of OPR/BOD: Determined systems manual structure for exterior building enclosure systems; Coordinated with design team for Schematic Design (SD); Thermal modeling review and material selections • Design reviews of SD’s, DD’s, and CD’s: Noted considerations, which are ideas to maximize profit, create efficiencies, and discuss constructability; Noted recommendations, which are red flags on design as it relates to continuity, material compatibility, and building enclosure failure concerns • Developed design concepts and detailing with Architect of Record (AOR): Design-Assist on innovative solutions and product selections (fins, channel glass, eyebrows, terraces, planters, parapets, connection points, waterproofing (blind-side below grade through roofing), metal panels, unitized curtain wall) • Developed building enclosure commissioning specification: Used as a section in the project manual • Developed building enclosure commissioning plan: Record of project description, contacts, expectations, list of commissioned specifications, and scope of work included • Reviewed and provided advice on mockup design and construction: Recommended various systems shown for interfacing details, constructability, and quality • Interviewed enclosure subcontractors for final award selection: Participated in the panel of interviewers to select the top three candidates for each enclosure subcontractor • Reviewed enclosure subcontractor bids for feedback • Reviewed and commented on RFI’s • Provided value engineering options • Preconstruction & coordination meetings (weekly, or as needed) • Work sessions with AOR, GC, and Enclosure Subcontractors • Submittal Reviews • QC Checklists • Quality Assurance visits and reporting • Managed Issues Tracking Log in BIM 360 • Field Performance Testing and reporting, including air barrier, air infiltration, water penetration, water spray, electronic leak detection, and roof uplift tests, per AAMA 501.2, ASTM E1105, ASTM E783, ASTM E 1186, ASTM D7877, and ASTM E907 • Performed retests on any failed field performance tests • Reviewed enclosure material warranties • Reviewed Operations & Maintenance manuals • Generated project closeout manual including all commissioning history • Post-occupancy enclosure review including infrared scanning to verify how the building enclosure is functioning between 8-10 months after construction As we delivered our scope of work, it was important to consistently communicate using BIM360

Solution: There were various challenges, as the new expansion building was being built to align with the existing building, which was in full use. We consider the following notable and/or innovative: • The existing building wall had to be demolished and replaced with a new wall. With the building being fully occupied and open to the hospital, the solution was to 1) remove the stone on the existing wall, 2) apply temporary waterproofing to that wall, 3) build the new wall at the interior of existing, for proper connectivity to the new building, 4) demolish the existing wall, and 5) use the removed stone for the new wall. This allowed 100% protection of the occupied space, while building a new wall which would connect from existing to the new expansion. • The termination bar at the vertical roof membrane required a fastener spacing of 12”, yet the wall stud spacing was designed for 16” on center. We recommended that the termination bar be moved a few inches to the concrete for anchorage, instead of the stud wall. This would provide consistent fastening, plus concrete is stronger than sheathing. • There was concern about performing a whole building air tightness test after all new materials are installed and how the test would work with the expansion joint between the existing and new building. We offered diagnostic targeted ASTM E1186 testing solutions through various high-risk areas of the new building to verify proper constructability of air/water/vapor barrier systems, which resulted in an airtight building. • The design included wood composite panels, soffits, and vertical fins. The first issue was that the supply chain demand was a challenge for the wood fins and alternate sources were being researched. The second issue was the wood fins were exceptionally long and heavy, so the structural support was being reevaluated. The AOR was considering splitting the fins in two, which may change the aesthetics. We suggested changing the wood fins to aluminum tubes with powder coating to match the wood-look. We had wood finish samples sent to the AOR, with a 20-year warranty. This would solve both the structural and the lead time issues and prove to be sustainable. • There was a design challenge on how to tie the parapet to the curtain wall with anchor interference and proper structural support of the curtain wall. We suggested using the curtain wall as the parapet including steel loaded mullions anchored directly at the roof edge. Doubling up dissimilar assemblies can create waterproofing challenges and, in this case, structural challenges. This suggestion was a winner. • The 18-foot-tall channel glazing did not have proper testing reports, die capacity analysis charts, or engineering for the design intent to span "backlit" floor slabs. The manufacturer agreed to engineer these spans specific for this project. All details were verified and resubmitted to show conformance with all applicable codes and the RWDI Wind Tunnel Study developed for this project.

Value: • Tying in certain assemblies from the existing building to the new building, such as the fully enclosed bridge with glazing, the below-grade waterproofing, and the vertical walls, while the building was fully occupied, was communicated and sorted out during the preconstruction meetings. Understanding the connectivity, waterproofing continuity, and sequencing was key. • Feedback from the Architect was that there was value in QA/QC collaboration, as we recorded any construction deficiencies during our QA visits, the GC then reported back the repairs, and we closed out the issue. We acted as a checks and balances to the construction team, which was valuable as a consultant. • We found incompatibility of materials, variances from the specifications, and substitutions which weren’t properly requested (per specification requirements), during submittal stages. Shop drawings were also commented on for verification of proper placement of sealant joints and surrounding condition coordination. • Our experience with quality assurance observations and reporting, along with industry knowledge, made us valuable in the enclosure subcontractor selection process and our recommendations were taken. • Some of the curtain wall anchorage was detailed to the floor slabs in a manner that would not properly capture the mullion structurally with deflection in mind. Although the appropriate anchorage was communicated by us, we also recommended a full set of curtain wall calculations, which officially changed the anchorage design. • During one of our preconstruction meetings, the glazing subcontractor communicated that the glass lead times were so long that the schedule could not be met without guaranteed opening sizes. We suggested ordering the projects full square footage of glass that can be fabricated after field measuring. After all, the lead time was mostly in the full size glass sheets, not the fabrication. • During the design review process, we reduced transitions between dissimilar materials, verified continuity of waterproofing and vapor barrier details throughout the enclosure, and made recommendations/considerations to various details. During the QA observations, these comments were verified as being installed/constructed in the recommended manner. In one case, as it related to an unusual transition with a planter on a terrace, tightly fit between a glass handrail and curtain wall, some of these details had to be worked out in the field to ensure proper waterproofing. We maintained the project’s vision and design intent, while keeping sustainability and resilience in mind throughout our scope of work. The value of having a consultant was preventing building enclosure leaks, while collaborating as a team above standard practice to develop a beautiful building enclosure that functions throughout the intended life cycle and more.

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Additional Info: With this project being a hospital expansion, there was a heightened level of concern for indoor air quality, air & water infiltration, daylighting, patient comfort, happiness, and human health safety awareness. Sustainability in the design was standard practice, but resiliency was always in the forefront of our communications and decisions. The architectural design revolved around this; however, during the time of material procurement, the supply chain demand issues did not allow for specific materials to be either fabricated or delivered within the required schedule. Thankfully, our BECx involvement was very collaborative and we were able to offer innovative solutions to meet the needs of the architect, construction team, but most importantly the end user. The various types of facade materials interfacing with one another could have created breaches in the building enclosure, which is counterproductive to meeting the "heightened level of concern", so this was reviewed, communicated, and tested throughout the scope of our BECx work to ensure the appropriate performance requirements were met. We worked diligently to meet the needs of the design intent, building performance, and aesthetics, even when materials changed.

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