Proj Overview

PROJECT OVERVIEW

During a multi-year assessment of the circa-1974 museum, the owner identified several issues to be addressed. Most significantly, the precast panels on the exterior façade were no longer viable, as they had compromised lateral attachments at many locations. And because the original structure had been built in in a fast-tracked manner, there were numerous imperfections in its original construction.

The initial project focused solely on the exterior 44,400 square feet of precast recladding with a future contract to be awarded for the full revitalization of the interior (60,000 square feet). The corrections also included the installation of new waterproofing and insulation layers between the precast walls and existing structure, which in turn enlarged the façade by 4 inches in diameter.

INNOVATIVE PRECAST SOLUTIONS

The team incorporated the use of laser scans and data-point modeling, as well as traditional surveying methods, to determine the existing conditions of the underlying structure. The precaster, in turn, designed and implemented an innovative system for hanging the panels that would accommodate the variable conditions, while also dealing with minimal to non-existent access behind the panels as they were installed.

Most importantly, the panels needed to match the appearance of the original panels when the museum was first constructed. That necessitated a painstaking effort whereby the precaster’s team hand sorted the aggregate to match the existing panels’ sand-blasted, exposed aggregate finish. Additionally, there could be no part of the panel larger than a quarter without exposed aggregate, and it had to be consistent in color (the aggregate had seven distinct colors depending upon the vein of the rock).

Following the precaster’s internal QC inspections at its manufacturing facility, the client performed an additional 30-point inspection of the panels upon their arrival at the site. The owner’s representative, general contractor, and architect individually inspected every panel from 10 feet. Procore was used to track and document inspections and the resolution of any concerns. By project’s end, the team had erected 673 pieces wall panels, along with numerous blended plugs and filler pieces wherever access holes were needed to complete connections. All the precast panel restoration work was performed as the museum remained open. The challenging, and often complex job, was completed on time and on budget, bringing the iconic museum back to its original grandeur.
 

 

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Project Team

General Contractor:

Grunley Construction

PCI-Certified Precast Concrete Producer:

GATE Precast Company

Architect:

CallisonRTKL

Engineer:

Silman

Precast Concrete Specialty Engineer:

DEVITA  
 

Key Project Attributes

  • There were extremely tight aesthetic requirements at the Museum site. Given its central location on the National Mall and historical significance, external approving parties such as the U.S. Commission of Fine Arts Commission of Fine Arts and the Smithsonian’s Office of Planning, Design and Construction (OPDC) were heavily involved in project oversight.
  • While the building expanded in diameter to facilitate improvements to the waterproofing systems and additional insulation, it maintained the same relative panel sizes (90 equal panels) and joint layouts around the building. This was done while also updating the design to current codes, including blast design requirements.
  • The entirety of the project was modeled in BIM using digital scans of the underlying structure. The digital scans were “backchecked” with more traditional surveying techniques to ensure that they properly represented the underlying structure. Incorporating the digital scan technology, still in its infancy, into the BIM model in a functional format that enabled the team to make design adjustments was a significant challenge. To visually communicate the design to the client, the precaster created full scale mockups of eight panels, which remained on site until the project was completed.
 

Project/Precast Scope

  • 60,000 square feet of exhibition space; 44,400 square feet of precast concrete panels
  • 673 pieces of precast wall panels; 230 plug and filler pieces
  • The new precast concrete cladding was thinner than the cladding on the existing building to account for the building’s new insulation and water barriers and included
  • The use of precast afforded greater control over the process and enabled the owner to maintain museum operations with minimal noise impact