This week, Forest City Ratner broke ground on the next phase of the Atlantic Yards, a 32-story residential tower known as B2, which will be the world's tallest modular building. It will have 363 residential units and 4,000 square feet of retail space, which is great and all, but what exactly does modular construction entail? To get some answers, Curbed spoke with John Dolan, a project executive at Skanska USA Inc., the general contractor on the project, who worked with SHoP Architects, structural engineer Arup, and consultant Xsite Modular.
How does prefabricated construction work?
Much of what is happening today began 20 years ago. We're pre-manufacturing elements of the building off-site, whether it's a pump, piping or valve that that may be put on a truck, shipped to a job site, taken off a crane or a forklift, bolted down to a floor and connected to other pre-manufactured elements. That has been going on for years.
This is a much bigger project. What's different?
We're taking a frame?we're calling it a chassis?our largest is 36 feet long by 14 feet wide and 10-foot tall, a steel tubular frame that will house all the elements of a single studio apartment or a portion of a multi-room apartment. We have drywall framing, the light fixtures, all the appliances and all the details in bathrooms?down to the toilet paper holders on the wall?in the factory, packaged up and shipped over. The chassis are built at steel fabricators manufacturers. They'll ship those to the Brooklyn Navy Yard and then to Atlantic Yards. For the most part, one chassis will be on one truck. In some cases, two small chassis will be on one truck.
How much do you save compared to conventional construction? How much faster is it?
We estimated that it's around 12 to 15 percent in savings based what we think our effectiveness will be. We hope it'll be better than that. It does provide tangible savings, because we're producing it around four months faster than conventional construction. We expect to be done in 18 months. The conventional construction would have been 24 months.
How does the prefabricated structure compare to a normal building?
There is a denser collection of material. The overall building is lighter. Our column spacing is tighter than the normal 25 by 25-foot column grid. Our column grid is every 14 feet, but I don't want that to sound like a detriment. It's very strategically laid out so the columns are not noticeable. Most of the transitions are done in the doorway and archway. You don't see the columns, you don't know the steel columns are in the walls, although they may be wider. It's not as noticeable because we have laid out the apartment where they're concealed inside the wall.
How has new technology helped this process?
We have relied heavily on 3D modeling in the past to ensure our mechanical and electrical piping all had space. This particular project is taking the modeling effort to a new level. Everything that will be produced in a factory will be on a drawing. What we don't want to have happen is have factory production stop to try to find the dimension for something like a light switch. Everything has to be done in the model.
What impact will prefabrication have on the construction industry?
New York City building trade unions have worked very closely with Forest City Ratner and Skanska. I've worked with unions throughout my 30-year career. It's an opportunity to evolve. We all want it to pay the bills. I think it's better for the industry that we find strategies to build elements and entire projects offsite to minimize the amount of construction that occurs on the work site. The Atlantic Yards site is very difficult to navigate around. We're reducing the amount of activity. There will be fewer trucks.
Have you done any modular buildings before?
Skanska has already completed a modular data center up in Quebec, Canada for Telus, a communications company. It was partially manufactured in Danbury. Conn. by a mechanical contractor. Some of the technical aspects of the data center were shipped out from Wisconsin. We're building a second data center in British Columbia right now, same process. We've also done modular in Miami Valley Hospital in Dayton, Ohio.
What's your outlook for the future of prefab construction?
This will be the first of six million square feet that Forest City Ratner has committed to the city of New York. We hope this will be something we can do around the country. As a national builder, we are in nearly every state and this is a valuable system for any client. I'm expecting to go beyond the borders of New York and New Jersey.