--

--

Engineering needs
Not all New York City buildings can physically support a rooftop addition. However, because the modern modulars are constructed from lightweight materials (typically including quite a bit of glass), most warehouse-type buildings found throughout the Burroughs easily support the weight.

The technical term “live load” indicates the amount of weight a structure can support. The building in downtown Manhattan at 117 Hudson Street is a typical loft conversion. It carries a live load of 100 pounds per square foot. A modular normally weighs 55lbs per square foot. At the upper end, they tip 80 pounds.

Before dropping the home onto the roof, steel beams are placed on top of weight-bearing piers set at intervals according to the building’s internal structure. The modules rest on the beams. This strategy minimizes disruption and penetration of the existing roof, while providing access to underneath tubes and electricity connections.

Currently, the largest modules that can be truck-shipped measure 62 feet long and 16 feet wide, and weigh 40,000 pounds. Many producers ship sets of smaller modules. Even at the large extreme, however, there are 240 ton cranes in New York that can reach the required height and carry the weight without problems.

Time
From initial contact to move in, expect 9 to 18 months to pass, depending on permits and specific, buyer-determined construction requirements.