The week before the Fourth of July (2023), I found myself speaking with Adriane Quinlan, a talented journalist from Curbed / New York Magazine, who was conducting research for an article on acoustics and codes in New York City apartment buildings. She had found occasions when neighbor-on-neighbor conflict due to acoustics had led to confrontation, everything from lawsuits to murder. She was curious as to how neighbor-disturbing inhabitant noise, from speech (arguments), to footfalls (stilettos), to loud music (piano practice and hip-hop), was covered in the building codes. Surely, she felt, the builders who build such thin and seemingly sound-amplifying walls between apartments must be in violation of some code. Adriane was also curious as to how compliance was enforced, other than dispute resolution by the NYPD. I am not sure I was much help to her, as we have designed only a few multi-family buildings and our details and construction specifications well exceed the bare minimum codes most developers follow. Notwithstanding, her questions got me to thinking about acoustic privacy between neighbors in our more familiar high-end market.
In the earliest days of cities, prior to electricity, indoor plumbing and elevators, single family homes were typically rowhouses with shared wood-framed party walls, and with gas lighting and outhouses in the rear yard. Subsequently, these rowhouses would be built with masonry (brick) party walls, yet still relied on heavy timber floor framing (joists). Both types of homes can still be seen within the five boroughs of New York City, and throughout other cities of a similar age that have coherent zoning regulations and landmark preservation enthusiasts. The rowhouse still defines and dominates the urban residential landscape in many neighborhoods of many cities. As an example, our firm is currently overseeing the preservation and modernization of an original wood-framed house in Nantucket that is one of five conjoined rowhouses built in the 1830’s. As we go through the archaeological process of demolition, we are transported to an earlier age, both in lifestyle and in construction technology. Notably, a neighbor has let us know that he is worried by the early phase of exploratory demolition and by what may come after, as absolutely everything can be heard between the two houses. We will certainly specify additional insulation at the paper-thin walls shared with the home’s neighbors.
Following the row houses were the walk-up tenements, essentially taller buildings constructed as double-wide and triple-wide townhouses of apartments with a common stair. Instead of serving one family or two if one counts parents and/or staff, these tenements provided housing for as many families as could be accommodated and were in many ways, the progenitor of the slums. One can imagine that secrets among the tenancy were rare with so many living in such tight quarters. If only walls could talk, as the banging steam radiator pipes surely did.
This building typology featuring masonry walls and wood-framed floors could also be elegant, which I note every time I visit Venice, Italy, and see that this exact methodology was used to construct the palazzos that line the canals (without the fire escapes and overcrowding – at least within the grand apartments). In the States, and specifically in New York City, the Gilded Age brought us electricity, plumbing, elevators, and for larger structures, the two-way reinforced concrete slab. These construction technologies together allowed architects like Rosario Candela and Emery Roth to surround Central Park and grace the major avenues with their exuberant luxury apartment buildings we collectively refer to today as pre-war.
Enter one of these ‘Class A Fireproof’ buildings and you can feel the hush, almost as if all sound has somehow been removed. Speaking in whispers seems the only appropriate behavior. This absurdly quiet old-world sensibility is the product not just of the doorman’s demeanor and the intimidating countenance of the apartment dwellers, but even more due to the construction technology underlying the confectionary ornamentation.
The grand buildings all feature rigid steel frames whose members (columns and beams) seem oversized today, as their architects and engineers did not enjoy computer-aided-design programs that enable the minimization of structure. The exterior walls are generally masonry (brick / limestone / marble) and were built to withstand the test of time as they have. Inside the buildings, the floors are supported with thick (twelve inch) two-way reinforced concrete slabs with an insulating layer of six to eight inches of cinder fill (vermiculite) above the slab and below the finish flooring. Sound transmission, whether vibration or air-borne, has trouble transferring vertically from apartment to apartment through this heavy mass. Similar to the floors, the walls of these pre-war buildings were largely made from either terracotta masonry or gypsum blocks (bricks made from gypsum, the same material in today’s sheetrock), which in turn, were covered in thick plaster. If you rap your knuckles on an interior partition of an older apartment, you will hear a deadness, with no drum-like amplification of a modern stud and sheetrock wall.
The post-war (WWII) boom brought a rush to build lighter, brighter, and less expensive apartment houses. Emery Roth, who gave us such wonderful icons as the San Remo and the Beresford, also brought us the post-war white-brick superblock buildings of the Upper East Side (mostly as the successor firm Emery Roth and Sons). While the early post-war buildings shared many sensibilities and construction technologies with their pre-war brethren, gracious rooms and gypsum block partition walls, the developer-fueled rush to build faster and less expensively was on. Stud walls were invented, first heavy gauge steel with lath and plaster, and subsequently, light gauge and ever-thinner sheetrock – insulation optional. Gone, too, was the vermiculite fill as finish flooring could be more economically installed directly above the concrete slab, which was also getting thinner year by year. Neighbors could finally hear each other’s whispers.
Today, when we renovate apartments in post-war buildings, one of the most important interventions we undertake is to improve sound attenuation between apartments. We routinely specify a floating floor system, with the wood floor installed over two layers of plywood subflooring laid perpendicular to each other, and with an acoustic underlayment beneath primarily made of specially formulated rubber. We double the sheetrock and add sound batting between the wall studs. In extreme circumstances, the tracks in which the metal studs stand can be installed over resilient channels and suspended sheetrock ceilings can be hung on springs. And when we are aware that neighbors are known to practice the piano, we build walls within the walls, seeking to create even greater sound isolation through separation and adding mass. Having recognized the benefits of sound attenuation in post-war buildings, we also use many of the methods when working in the old-world pre-war buildings. You simply cannot have enough sound separation between neighbors, especially for those who can afford not to hear one another.
While the foregoing assesses sound transmission and mitigation between neighbors in luxury apartment buildings, similarities appear when studying the construction of single-family homes in the suburbs and beyond. Walk through a significant older home on Long Island’s North Shore or in Greenwich, CT, and in hundreds of other resort and bedroom communities, and you experience that same hush of the grand apartment buildings lining Central Park. These mansions (not McMansions) were built to last generations. The Frick and the Cooper Hewitt Museums on Manhattan’s Upper East Side were originally single-family homes in the ‘country.’ Comparing this construction sensibility to mid-century suburbia is even more extreme than comparing pre-war and post-war buildings in New York City. And yet, something interesting and maybe unexpected is happening. Today’s energy, seismic, and hurricane codes are having an affirmative impact on single-family home construction, and in many cases, we are building better than previous generations. The codes governing the components of a home’s exterior envelope (insulation, windows, sheathing) have all been strengthened, resulting in tighter buildings that save energy and are less likely to be blown away in a hurricane or reduced to rubble in an earthquake. By satisfying the energy, seismic and hurricane code requirements, properly designed and built new homes are more resilient and sustainable, and for the purpose of this essay, quieter.
And with electric cars making roadways quieter as well, homeowners will be able to open the windows and hear the birds trilling; provided the air quality allows letting in the outside air. Finally, the pandemic brought us a remote work culture, and when working from home, people are demanding greater sound insulation between rooms and between neighbors. Taken together, today’s mandates, whether code-related or programmatic, are all combining to create quieter homes, and optimistically, not just for those who live on Park Avenue or in an early twentieth century mansion.