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Habitat Magazine Insider Guide



Fixing the Cracks

Our client was a 168-unit co-op on the Upper West Side that was undergoing routine facade maintenance as part of the Facade Inspection and Safety Program. On the fourth floor of this building is a 500-foot-long water table, made of stone, that spans three separate street facades. Water tables are horizontal architectural elements that deflect water running down the facade away from lower courses or the foundation. The stones of this water table were heavily soiled by carbon and organic staining. When we did a small sample cleaning, it revealed extensive cracking in some of the stones. We had anticipated selective repairs of about 24 of the stones, but once we did the actual cleaning, we found that every stone had anywhere from one to eight cracks. It turned out that about 133 stones were going to require some aspect of repair.

Wear and Tear

With water table cracks, age is always the cause. Over time they begin to crack due to moisture retention and the freeze-thaw cycle. These stones are big — 3, 4, 5 feet in width and anywhere from 250 to 1,000 pounds each. This building dates back to the 1920s, and there had been standard repairs, where you cut up the crack and apply sealant. But that’s a short-term fix. When we looked at those repairs more closely, we saw that some of the stones were getting worse. 

We gave the board three options. The first was to continue the standard crack repair. It’s relatively inexpensive — it would have been an $85,000 change order on a $2 million restoration job. But the visual downside is pretty significant. The water table is only about 30 feet from the street, and the aesthetics would not be great. And again, it’s a short-term Band-Aid.

The second option was to do the crack repairs but also apply a breathable coating that would give an additional layer of protection and hide the repairs better. It’s slightly more expensive, a $115,000 project. But the problem is that the coating tends to flatten out the natural finish and texture of the stone, and it becomes a maintenance item. Just like painting a railing every 10 to 15 years, we would have to go back and recoat the water table.

Option number three was a full stone replacement, which is a very significant job. Production and insulation lead times are six to eight months. And with some of these stones weighing up to half a ton, it’s going to require additional equipment, including pipe scaffolding and chain lifts. The positives are that the new stones would last decades, and replacing them affords the unique opportunity of waterproofing behind the stones, which adds an additional layer of moisture protection for the building. With all of that, though, it came to about a $500,000 change order.

Value Engineering

However, since we wouldn’t have to clean all 500 linear feet of stone or do any crack repairs as originally planned, we were able to get the price down to just under $200,000. The building is in a landmark district, and we worked with a vendor who matched the texture and finish of the original stone so effectively that we are replacing the stone in kind. In the 1920s they used cast stone, which is a form of precast concrete, and now we use architectural precast, in which you add pigments and a few other additives to mimic natural stone. It’s a version of value engineering because it’s fairly expensive to get 500 linear feet of limestone, haul it down, install it and carve it, as opposed to just casting it in a mold. The first run of stones is just going in, and they look great. 

With a lot of aspects of building facade restoration, there are different paths forward. So boards should engage their consultant and ask him or her to provide options. There’s no one end-all, be-all solution.

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