Freedom Tower
A construction worker signs his name on one of the first steel beams of the new Freedom Tower being constructed on the site of the the former World Trade Center in New York September 11, 2007. Reuters

Thanks to raging residential demand, two ongoing major projects, and post-Hurricane Sandy infrastructure work, construction spending in New York City is expected to top $31 billion in 2013, a 14 percent jump from just a year ago.

Here are six things you need to know about what's being built in the nation's largest city, according to the Building Congress, a trade group that tracks data.

• Construction activity is expected to continue building momentum in the coming years -- growing to $33.4 billion in 2014 and then $37.0 billion in 2015.

• If 2015 construction spending matches the forecast of $37.0 billion, the volume of work produced would be in line with numbers from the height of the 2007 building boom, even factoring for inflation.

• The Building Congress projects the addition of 4,200 new construction jobs in 2013 -- up to 119,100 from 114,900 in 2012. The forecast anticipates a total of 123,400 jobs in 2014, and 129,700 in 2015.

• Residential construction spending doubled between 2009 and 2012, and it is expected to continue this surge by doubling yet again by 2015.

• Non-residential construction, which includes office space, institutional development, sports/entertainment venues and hotels, is forecast to reach $10.3 billion in 2013, up from $8.9 billion a year ago.

• Government spending, which includes investments in mass transit, public schools, roads, bridges and other essential infrastructure, is forecast to increase from $13.4 billion in 2012 to $13.7 billion in 2013 before dropping back to $13.5 billion in 2014 and then $12.8 billion in 2015.