September 4, 2023
We just started a renovation of a historic townhouse in Long Island. Located in the historic Hunter’s Point District, the neighborhood is one of the only Landmarked districts in the downtown Long Island City area and one of the best-preserved examples of late 19th century Italianate, French Second Empire, and Neo-Grec townhouse architecture in Queens.
Demolition was recently completed, and this was our fist job site visit to check on the conditions of the structure prior to framing. Throughout the house, the floors were sagging and uneven, and we were able to document the existing conditions of the floor to give a sense of what causes these underlying issues.
After removing the plaster and sheetrock, it’s much easier to see the actual structure of the building. The “party walls” (the two walls separating this townhouse from the the neighbor’s townhouse) are brick, and they support heavy timber joists, typically made of a soft wood like pine or fir. This building was built in the late 1800s (before mass produced factory dimensional lumber) so the teams of men and horses who built this originally had to transport what were essentially rough cut “trees” to the site to serve as the main structural elements for ceilings and floors.
Though these are bigger than typical dimensional lumber we would see today, the use of soft and often poorly dried wood tends to lead to issues of floors sagging over time. We have seen floors sag as much 3″ over the course of an 18′ span. Needless to say, this causes numerous issues over time, such as cracking of trim and plaster, uneven baseboards, and creaking, unlevel floors.
How did these floors last so long without sagging? Well, historically the spaces in brownstones and townhouses were much smaller, and more subdivided. In the image above you will see the remains of a “relieving wall”, basically a wall that was built along a hallway that was intended to function as a kind of support wall to fight the sagging beams. Usually these walls will be composed of slightly thicker pieces than the rest of the wall framing.
The problem is that over time, as we have increasingly moved towards more “open-plan living” styles, these walls tend to get removed to make spaces more open, or new openings get cut into the wall without consideration of their true functional purpose. Over these decades of successive renovations, the floor joists lose their support and they begin to sag.