Alamo’s AC may be causing harm

San Antonio Express-News - By Scott Huddleston

Having withstood an 1836 battle and centuries of exposure to the elements, the Alamo’s biggest threat today may be air conditioning — a modern amenity that experts fear is threatening the fragile limestone walls of the Texas shrine’s iconic mission-era church.

George Skarmeas, who is leading a process to craft a master plan for the Alamo and surrounding area downtown, said preservation of the church, the “most significant artifact” at the site, has become a key point of focus.

The effects of up to 2 feet of soil added in layers at the base of the church over time and a concrete roof that has covered its walls since the 1920s also are concerns.

“The early signs are that we have some worrisome behavior of the building,” Skarmeas said.

Chunks and flakes of limestone debris that have fallen from the walls onto black butcher paper on the perimeter of four side rooms in the church since Sept. 1 provide new evidence of the building’s gradual decline.

“This is actually significant loss,” Skarmeas, design director with Preservation Design Partnership of Philadelphia, said during a recent walk-through of the 250-year-old church to show the accumulation.

An update on the master plan, being developed for the city, Texas General Land Office and nonprofit Alamo Endowment, will be presented at a 2 p.m. Wednesday City Council work session, to be streamed on the city website and aired live on cable channel TVSA.

The final plan, due in mid-2017, is likely to address options for a modern visitor center, removal of traffic from the city-owned Alamo Plaza and historical interpretation of the area — site of a Spanish colonial mission with close to 1,000 recorded burials in the 1700s, and the famed 1836 siege and battle for Texas independence.

At a recent public meeting, City Manager Sheryl Sculley said the plan will benefit local residents, not just visitors, after last year’s designation of the Alamo and four federally run missions as a UNESCO World Heritage Site.

“Even more people will be coming to San Antonio,” she said. “We also want this designation to include an educational component for those who live in San Antonio and may not know about the layers of history for not only the other missions, but also for the Alamo.”

In addition to $31.5 million in state funds allocated by the Legislature for master plan projects, the city has programmed $17 million and proposed up to $22 million for plaza improvements as part of a 2017 bond referendum. The Alamo Endowment also plans to raise funds privately for the project, including structural preservation work.

Pam Rosser, the Alamo’s on-site conservator since 2010, said she is glad to have Skarmeas and his team at the state shrine, helping discern the best path forward for the revered building. The accumulations on black paper of limestone chips and flakes that normally are swept out on a daily basis provide a “good visual” of the structure’s decay, she said.

“It shows proof that the walls are losing debris,” Rosser said.

Discoloration and other effects of “rising damp,” an upward migration of ground moisture, have been documented for more than a century on the exterior walls of the Alamo church. The master plan, for the first time, is bringing together all available resources to document the building’s various construction phases and the use of radar imagery, high-resolution photography and other new technology to track its decline.

“Some of these effects are slow in the way they manifest. But the destructive impact may be very immediate,” Skarmeas said.

One of his key concerns is the air conditioning in the church that removes indoor moisture while thousands of visitors, often sweaty from the Texas heat, bring in “another load of moisture” and humidity.

“So you’re going into a vicious cycle,” Skarmeas said. “The building was never intended to be that way.”

The church has been air-conditioned at least since 1961, when an ad and article in the San Antonio Express chronicled a ceremony to turn on the new General Electric units — all-electric heat pumps that cooled without water and heated without a flame.

“Visitors to the Alamo will find the ancient building cool and comfortable as three G.E. Weathertrons … keep the temperature consistently pleasant from their concealed locations,” the article said.

But the Express-News has reported since 2010 on the concerns of preservation experts that air conditioning could be compromising the building’s integrity, possibly creating a humidity gradient that draws moisture into the church and even through its walls, comprised of stone, mortar and a rubble interior.

Battle Brown, a documentation and project management specialist based in Pittsburgh, told the Express-News in 2013 that the air conditioning could be drawing moisture through the walls, contributing to deterioration and discoloration of the walls and blistering of a newly painted roof and ceiling.

Last year, at a conference at Texas A&M University that focused on preservation of the shrine, structural engineer Patrick Sparks said he had used infrared data to identify areas where air conditioning was cooling the walls, possibly causing condensation and “potential delamination.”

Skarmeas said the solution may be an air-circulation system that does not add moisture instability, to “create a relative comfort for the occupant.”

He said he also wants to know if layers of surface soil and pavement that have covered the church’s lower walls should be removed, to help contain the rising damp and restore the building to its historic context. He said he’s yet to learn the depth of a slab that lies beneath the church’s flagstone floor.

Since the church was not designed to have a steel-and-concrete roof, more study is needed to see how well the walls are handling the weight, Skarmeas said.

Some Alamo devotees have raised concerns that the master plan will marginalize the 1836 history — the primary attraction for visitors from around the world. Skarmeas said the plan will respect that chapter in the site’s 300-year history, as well as its emotional ties to descendants still living in Texas today, and put the siege and battle in proper historic context, as an event with a global impact.

“It’s almost like a symphony, where you have everything building up to a crescendo, and 1836 is the crescendo in the symphony,” he said. “And different ears hear the crescendo differently. They absorb it in different ways, emotionally, intellectually and viscerally.”

Source: San Antonio Express-News