Repairing San Sebastian from the inside out

By Nickky Faustine P. de Guzman, Reporter

DESPITE ITS AGE, San Sebastian Church is more than strong enough to withstand the Big One — the magnitude seven earthquake that scientists say will hit Metro Manila and neighboring provinces sometime in our lifetime. But while it is sturdy, it is also rusty. The only steel church in the country is in a state of decay: it has more than 300 leaks and its facade and interiors are rusting. And to the horror of its current restoration team, it found that denim jeans and newspapers had been wedged in between joints in an attempt to stop the leaks.

Built in 1881, the towering church in Quiapo is made from sheet metal and steel girders. It has 132 strong columns, “which were way stronger than what the church needed in the 19^th century. It was constructed at the aftermath of the earthquake of 1880, one of Manila’s devastating earthquakes,” noted San Sebastian Basilica Conservation and Development Foundation, Inc. (SSBCDFI) director Tina Paterno, in an interview with ����ý in April.

SSBCDFI is a Securities and Exchange Commission-approved organization composed of Recollect friars and professionals with two targets in mind: to restore the beauty of the church and to promote awareness among the public of its significance.

Designed by Spanish architect Genaro Palacios, the structural metal of San Sebastian Church was manufactured in Belgium and erected in Manila by Belgian engineers — it took a decade to finish from concept to execution. 

“It was designed amidst the rubble of the earthquake, so he (Mr. Palacios) had earthquakes in mind. The previous [church] constructions were made of masonry [which is] susceptible to earthquakes,” said Ms. Paterno, adding that since it was built the church has survived 11 major earthquakes.

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STUDYING THE PROBLEM
Still, while San Sebastian may be strong, it is not as tough as it was in days of yore. To diagnose the illnesses of the aging church, the SSBCDFI has spent four years doing careful studies, research, and planning.

One of the studies includes a look at its demand-capacity ratio to determine how much strength the church’s pillars are using versus their actual capacity strength. “The columns are strong, and they have a large reserved strength — but that is 125 years ago. How do we calculate its strength today in all its 132 columns?,” said Ms. Paterno.

Before conducting this test, there were other factors to take into consideration, including the corrosion rate — the speed at which the metal deteriorates — of each column. All of the 132 steel columns have their own corrosion rates which can vary considerably over time. But asking how fast the corrosion is taking place like asking when the Big One will hit. Nobody can plot the rate of corrosion per column, but what the team knows is that it is there and that they have to do something about it.

“Corrosion happens slow, and then it zooms in fast, but we cannot tell where we are in the chart, so what we want is prevention. Different parts [of the columns] are in different area of the map depending on their leaks. To map out all variables is probably impossible. We tried to model it, the engineers said we’re good, but we should not dilly dally. We want to catch up before it’s too late,” said Ms. Paterno.

So the demand capacity-ratio study could only come up with “a conservative assumption: there is a little bit of reserved strength.” And that “little” reserved power is still enough to survive the Big One.

“A column can carry a 10-storey building according to our engineers,” she said.

ACTIVE LEAKS
Previous attempts to restore the church included the repainting of the exterior facade, which was only superficial solution. The bigger problem lies with what is inside. “People don’t see [things] unless they know what they are seeing,” said Ms. Paterno when she invited this writer inside the church for a tour. A first time visitor, I told her the church looked amazing, if rather humid, and that it appears to be okay — and that is what many people think too.

She said there’s so much more than what the eyes behold. Behind the beauty of the church are its ugly problems: rusting steel and many leaking parts. She motioned me to a corner near the pulpit and there I found a hole in part of the steel wall. Ms. Paterno said to stick my hand inside it. Behind it is a hollow space.  

“The most challenging part of our work is seeing what is happening inside the cavities,” said Ms. Paterno. “The columns,” she pointed out, “are hollow,” The church core is empty, but it does not mean that it is weak. Imagine two metal plate walls, exterior and interior, held together inside by cross braces and strong rivets.

“It’s a hollow building. There are four metal plates with concealed rivets that are designed not to look industrial when the church, in fact, is built during the Industrial Revolution,” she said.

One would think that there is an inherent problem in having an all-steel building in a humid, rainy, tropical country — water and steel do not mix. It is a vicious circle: water (from rain, and the humid atmosphere) leads to rust, which leads to holes, which lead to leaks, which leads to even more rust, which leads to even bigger holes, and so on. When it rains, water pours inside the church. Of the 132 columns, the restoration team estimates that 90% of them have leaks; even worse, 40% of the columns have standing water — some as high as two meters — inside them. Some walls display white water stains.

“When you have rust [in walls or joints], it is going to start to warp open, so you have a bigger opening and then water comes in and the cycle just continues,” she said.

So what the team did in the hopes of stopping this cycle was to monitor the columns when it rains to see where the leaks were coming from. “Then you realize it is coming from some opening from the outside, and instead of [just] patching that opening, you say why is this open [in the first place]? What caused the opening? And it leads you to another mechanism, and another, until you figure it out — alas, the repair is superficial,” she said.

She added: “There are leaks that go through our columns and walls that we don’t see, that’s why on the outside it looks like everything is fine. But by looking into the structure we are starting to see how superficial past repairs were and how some were incompatible [with the problem], and the incompatibilities were done in the 1980s and ’90s.”

Past repairs were done in good faith but in bad taste. Some were hurried — the aforementioned jeans, old paper, and cement which is incompatible with steel, were once used to stop the leaks.

“Fast forward to today, [and] the little holes [have] become giant,” she said.

Some corrosion scientists have literally gone inside the hollow but narrow columns to clean the insides.

“A guy named Sebastian went through it — it’s big enough for a person to fit — and sandblasted it. His team did it in seven columns,” she said. The process starts with removing the corrosion, then priming the surface, and repainting the metal with clear paint varnish that is see-through but still providing corrosion protection.

“We’re going to have to think of this as a boat. It’s okay if the water comes in the boat [because it is coated]. Half the battle is how you prepare the steel when you repair it.”

The team hopes to finish the remaining restoration process in six years.

MAINTENANCE SINS
Despite the seeming incompatibility of steel and tropical weather, this, said Ms. Paterno, is not the real problem.

“The problem is not that the building is in a tropics environment… For steel to not rust, the paint on it must be intact. This way, it can survive easily in the tropics. So the problem is not steel in the Philippines, but that deferred maintenance, some poor repairs, and some flaws in design or construction in the past have encouraged these leaks, which causes rust,” Ms. Paterno had told ����ý in an interview last year. (��𲹻�:��)

“It’s not too fair to blame time and weather. There are three reasons why these are all happening: first, like I mentioned, is the incompatible and superficial past repairs. Then, there are parts of the roof that are too small for the volume of the rain, so it started to leak early on, and also, this building was constructed to be water tight [but is not],” said Ms. Paterno.

Since the church was first built, it was subject to typhoons, regular rain, and earthquakes. The seams of the church’s joints are sealed by a “historic �����������ⲹ��(filler or putty) composed of linseed oil and chalk,” which loses elasticity over time. Earthquakes cause joint movements and the masilya, which has become brittle, cracks, and the water then comes in through the crevices. The joints are not as watertight as they originally were. 

“Through time, [the steel] corrodes when the water comes in and when the masilya is not replenished, it will just keep on coming in there.”

Corrosion, then, is a colossal conundrum that needs to be addressed before The Big One happens.

“People don’t appreciate the restoration process, because to them ‘restoration’ is what they can only see on the outside,” said Ms. Paterno.

As The Little Prince said, “what is essential is invisible to the eye.”