Article No: 17

2006-04-28 09:24:55
ICFs in the city

A group of six-story townhouses recently erected above the crowded streets of Manhattan are not only the first row of new single-family residences to be built in their neighborhood in 150 years — they are also a striking demonstration of the benefits of building with insulating concrete forms (ICFs) in tight urban settings.

Photo courtesy of Studio Petrarca

For John Petrarca, architect of the Reade St. Townhouse project in Manhattan, ICFs became an option when he began to consider the difficulties of building with concrete block during the winter months. "ICFs offered an opportunity to build right through the winter because we could pour the concrete at freezing temperatures into the insulation," Petrarca said. "Then the more we looked at it, we saw the other advantages of ICFs.

"Materials handling was completely different. Instead of hauling and having to stage and manage concrete block up 75 feet, we almost threw the styrofoam up. The styrofoam forms offered a lot of advantages in terms of no cranes, no platforms and no reinforcing the floors to hold the concrete block up there."

Another advantage for Petrarca, who is partner in charge with Guenther Petrarca LLP, were lower labor costs. In heavily unionized New York, the use of ICFs allowed Petrarca's firm to hire carpenters to put up the forms rather than masons. "The masons and the concrete workers were only on the job for the one day the pump was here," he said.

But with the choice to use ICFs rather than concrete blocks came a steep learning curve, not only for Petrarca, who had never worked with ICFs, but also for all parties involved — even the ICF vendor, Reward Wall Systems Inc. Petrarca and his team were, after all, attempting to build the tallest load-bearing ICF structure in the world.

"To our knowledge, it's the tallest ICF structure built in which the walls are actually load-bearing walls," said Ed Storm, president of Omaha, Neb.-based Reward. "There are taller buildings out there using ICFs, but the walls are infill walls with concrete beams or something else supporting the actual structure."

With a project this sophisticated, engineering expertise was a major factor in choosing an ICF supplier, Petrarca said. Reward employs a full-time engineer in-house, and also contracts with an outside structural engineer who is considered an expert in load bearing walls.

Sophisticated engineering resources were exactly what Petrarca needed when local code agencies began to challenge various aspects of the townhouse construction. "We actually had to go to court with the building department here," he said. "In New York City, it's approved to build a concrete wall and then glue styrofoam to both sides of it. But the building department contended it wasn't approved to put the styrofoam there and pour the concrete between the styrofoam."

Photo courtesy of Studio Petrarca

That wasn't all. Code agencies also debated whether the Reward Walls forms, which are waffle-like and vary in thickness, should be calculated as a wall or as a series of columns. "This got very complicated," Petrarca said. "That's where Reward's engineering and their backup testing really paid off."

In the end, Petrarca and the building crew were able to surmount these obstacles, and four ICF-based townhomes were completed. The benefits of ICFs are apparent, said Petrarca, who happens to live in one of the townhouses himself. "These are tremendously solid homes," he said. The concrete and styrofoam insulation also help block out the noise from the busy streets of Manhattan.

Energy efficiency, another benefit associated with ICF construction, figured heavily into the plans for the Reade St. Townhouses. Not only were the homes built with ICFs, but they also feature radiant floors and special geothermal heating and cooling systems that use a minimal amount of electricity. The systems work by collecting the earth's natural heat in winter through a loop of pipes installed in a well 1,100 feet below the ground. Water circulating in the loop carries the heat to the home, where an indoor system uses electrically-driven compressors and heat exchangers in a vapor compression cycle to heat the home. In summer, the process is reversed, as the system takes advantage of the cooler temperatures below the earth's surface. Since the townhouses were finished early this spring, it's still too early to determine the exact energy savings derived from ICFs and the geothermal systems, Petrarca said.

At one level, ICF construction and advanced geothermal heating and cooling make the Reade St. Townhouses somewhat of an anomaly in densely populated Manhattan. But to most observers, the townhouses are simply well-designed structures that fit well with their surroundings. Situated in Manhattan's Tribeca neighborhood, the homes are built in the grand style of the area's traditional townhouses. The exterior features red brick, stone, steel and glass, like many other buildings in the area. The interior, meanwhile, is designed to let in a great deal of natural light with soaring space and open areas — the living room, for example, has 20-foot high ceilings and 17-foot high windows. The result, Petrarca said, is a townhome that offers the character of a traditional house but is designed with modern life in mind.

With several bedrooms, a penthouse on top, a large basement and an extensive entertainment area, each townhouse features almost 7,000 square feet of living space. The asking price for each home was more than $4 million.

Now complete, Manhattan's Reade St. Townhouses stand as a testimony to the success of ICFs in urban construction. But Petrarca acknowledges that ICFs are "an esoteric building technique for the city" and are "not urban material as of yet."

A more typical setting for ICFs would be a newer suburban or resort-type development. But in densely populated and longer established urban areas, ICFs are not even a blip on the radar screens of most builders, who are largely unfamiliar with ICFs as a building technique.

"The vast majority of ICF construction is taking place outside of the urban centers," Reward's Storm said. "That's something we're working to change."

As the Reade St. Townhouses demonstrated, ICFs can outperform concrete block in important areas such as speed of construction, flexibility and ease of construction, and cost of labor. Some of the other basic benefits of ICFs include improved worker safety, greater energy efficiency and noise reduction. These advantages have not gone unnoticed, Storm said, as the last two to three years have seen a "significant increase" in the use of ICFs for urban projects.

Still, many contractors and developers remain unfamiliar with ICFs, and qualified laborers with ICF experience are in short supply, Storm said. In addition, urban projects based on ICFs may, like the Reade St. project, encounter resistance from local code agencies. Another factor working against the quick acceptance of ICFs in urban settings is the slower pace of city construction. New construction often has to be preceded by the demolition of older structures, and government regulations and requirements are usually more thorough and more complex in cities than in suburban or rural areas. All of this results in urban projects having a longer time span from start to finish.

In spite of the obstacles, vendors like Reward are working to spread the word about what Storm says are the obvious benefits of ICFs for urban construction. They are also working "daily" to train more laborers to build with ICFs, Storm said.

But perhaps nothing will be so effective in introducing ICFs to urban builders as success stories like the Reade St. Townhouses. Petrarca had the flexibility to try something new because the developer and the contractor for the project were willing to experiment. "It's been good for everyone to see that this has worked," he said.