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The Trenton Bath House and Day Camp

Farewell Mills Gatsch Architects

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Project Name

The Trenton Bath House and Day Camp

Project Status



41,545 sq. feet

Construction Cost



Ewing Township, Mercer County


  • : Joseph R. Loring & Associates
  • Structural Engineer: Keast & Hood Co.
  • Electrical Engineer: Joseph R. Loring & Associates
  • Civil Engineer: RBA Group
  • General Contractor: Wu & Associates
  • General Contractor: De Sapio Construction
  • Landscape Architect: Heritage Landscapes

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Project Description

The preservation of midcentury Modernism has been a heated topic of discussion since the 1980s. Hampered by their relative youth and therefore by the impossibility of obtaining landmark status, many midcentury buildings have been lost, torn down to make room for new developments and new aesthetics. When the decision is made to actually restore a midcentury modern project, the question arises: To what preservation standards do you hold the restoration of a building with materials not all that different from today’s? In the case of Louis Kahn’s iconic Trenton Bath House, Princeton, N.J.–based Farewell Mills Gatsch Architects (FMG) answered without hesitation: the highest.

Kahn designed the facility, a pool, and a day camp in 1952 for the Jewish Community Center (JCC) of Ewing Township, four miles outside of Trenton, N.J. The bath house itself makes a Greek cross in plan, with four cubic pavilions (an entrance, men’s and women’s changing rooms, and clothes storage) each flanking one side of a square courtyard. The pavilions’ walls were constructed of unfinished CMUs, with a pyramidal, timber-framed roof floating over each. Kahn’s less-well-known pavilions for the day camp, slightly north and to the west on the site, were influenced by classical temple plans, with two open and two semi-enclosed structures. Here, Kahn used terra-cotta sewer pipe filled with concrete to form supports for precast deck roofs.

Fast-forward 50 years, and the structures were in “pretty rough shape,” says FMG preservation partner Michael Mills. “That had to do with the materials that were used, and the fact that some of the construction details were a little less than you would hope for.” But part of the problem, he says, “had to do with the poetry of the building. Kahn intended the water to run over the masonry surfaces. Unfortunately, in New Jersey with freeze and thaw, it also had a bad effect.”
Two of the day camp pavilions were on the verge of collapse, and the JCC wanted to tear them down entirely. But they were dissuaded by the county and others. The JCC retained FMG, with grants from the New Jersey Historic Trust, to conduct a preservation study—a job that both Mills and design partner Michael Farewell leapt at; both had visited the center as architecture students.

During the course of the study, it became clear that repairs were going to be costly, so the JCC decided to sell the property. Which is when Mercer County—which has supported several preservation projects within its borders—stepped in. “We knew we had an opportunity for open space, and we knew we had important architecture in the building,” says Mercer County executive Brian Hughes. The county bought the property from the JCC and transferred ownership to Ewing Township. With further grants, this time for capital improvements, FMG was hired to reevaluate the plan and to proceed with the restoration.

By this point, the floor slabs and several walls of the bath house were heaved and cracked. And there was the question of what to do about a snack stand that had been added unsympathetically to the west side of the bath house shortly after its opening in 1955. FMG tore down the snack stand, repaired the walls using authentic concrete block (see toolbox, page 69), repoured the floor slabs, and shored up the roof structure (“which was in remarkably good condition,” Mills says).

FMG retained Kahn’s original structural engineer, Nicholas Gianopulos, as a consultant, and used his firm on the project. At the beginning of the process, when things looked bleak, Mills recalls him saying, “Louis would understand if you had to take them down and rebuild them, or did something different.” The intention was to save everything if at all possible, but Mills recalls that “it was very helpful to hear that. We ended up in the middle—trying to do something longer-lasting that would help preserve the design.”

FMG created a new snack bar in a vocabulary related to Kahn’s and on the same grid. Farewell, who takes pride in the firm being able to “relate new architecture to existing architecture,” is quick to point out that the new construction is “deferential, because the real iconic monument here is Kahn’s work.”

The bath house and day camp are open again, but FMG already has its sights set on the next step: the parking lot. Kahn drew up plans for a bosque of trees that would both reinforce the geometries of the site and determine view lines, but his vision for the landscape was never realized, and parking was installed instead. FMG has developed an implementation plan, currently under review, to replace the existing paved plot. Here’s hoping that last step doesn’t take another 50 years.

Top photo courtesy Louis I. kahn collection, university of pennsylvania and the pennsylvania historical museum commission.

Concrete Block

When asked about the process of choosing concrete block for the restoration, FMG preservation partner Michael Mills laughingly calls it “Boring. Very boring.” But dig a little deeper, and he describes a compelling tale of material science. “It was a process of trial and error,” he says. “And we tried everything.”

While all of the walls of the bath house were still standing, the walls separating the men’s and women’s dressing rooms needed to be replaced, and large cracks had formed in others after years of exposure to water and freeze-thaw cycles. The broken blocks could be removed and replaced, but CMUs have come a long way, and the materials commonly used today were not a good substitute. Kahn’s original specifications yielded the texture and color, but the aggregate remained elusive. Conservation analysis identified crushed stone from the Delaware River and the presence of sand from southern New Jersey.

The team’s first thought: Alter modern CMUs to achieve the appearance of the original. In testing, two rounds of samples made using sandblasting and power-washing techniques approximated the texture, but it was unclear how the new blocks would weather.

In his notes, Kahn described the original blocks as “Waylite” blocks, a form of CMU introduced in the 1930s. “It’s a low-strength block,” Mills says. “It’s only a 3,000 psi block, whereas most modern block is 5,000 psi.” The architects found a manufacturer still producing Waylite blocks in New Jersey, and the texture of the block itself required little tweaking. The color, however, was another matter. Twelve samples were produced before the right color was achieved: a warm tan with blue and light orange aggregate. “We have all the samples,” Mills says. “I think the county’s going to keep them to show how difficult it was to match.”

Once the new block was installed, the masons filled in the voids in the block and added a thin mortar wash to seal the entire assembly. Then they added a thermoplastic resin to inhibit water intrusion, which will hopefully stave off the next restoration by a bit longer than 50 years.
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