This story is from The Pulse, a weekly health and science podcast.
This article was co-produced with PlanPhilly.
Nothing signifies Philadelphia’s rapid development like the sight of a metal or vinyl-clad house rising from a sea of red brick row houses.
The new homes repopulating many of Philadelphia’s row house neighborhoods tower above their venerable, redbrick neighbors.
In a city where over 70% of housing dates back to before 1960, these new buildings look dissonant. They don’t fit in with their surroundings. After they are built, critics say, and in their beginning stages especially, their composite parts look worryingly flimsy.
“Why doesn’t the developer, as a matter of courtesy to residents who live on the block, build something that comes as close as possible to what’s already on that block,” asked Councilmember Kenyatta Johnson, speaking for many of his older constituents’ feelings about new construction in South Philadelphia.
Why don’t we build them like we used to? And are these new homes actually going to age worse than the row houses of the 1800s?
It’s mostly about costs
The classic Philadelphia row house is built with an outer layer of hard-fired brick to protect the interior from the elements, with lower-grade salmon brick within. In these homes, the masonry is load bearing, and does structural work. Only inside the four corners of the brick walls is wood used to make floors, joists and other interior fixtures that won’t be exposed to the elements.
But the new houses going up in Philly and other traditional row house cities like Baltimore and Brooklyn come with wooden bones and exteriors made of a range of materials.
These “stick built” structures have a wood frame, which is then sheathed by insulation and a layer of metal, vinyl, stucco, or composite materials. When builders use brick and stone, they come as decorative flourish.
The shift away from structural brick began after World War II. Mid-century consumers wanted suburban homes that looked distinct from their urban counterparts and newer building codes no longer required brick. That, meant less demand for both the material and the masons needed to install it.
Seventy-five years later, the market for brick looks very different. It’s often shipped from far away and the labor costs are high.
“Masonry constriction is just not cost effective right now — it’s cheaper to build in steel than it would be to get masons out there,” said Anthony Delgott, the owner of Hybar Construction.
Delgott builds mostly in Graduate Hospital and Point Breeze, two old row house neighborhoods that have seen a surge of reinvestment over the last decade or two.
“I can stick-frame a whole house for $18 a square foot,” Delgott said. “I would have to pay triple that for masonry.”
And the costs wouldn’t stop there. There are other historical building techniques that are no longer allowed under contemporary building codes. If a builder chooses brick, the codes today require more masonry than 19th century builders would have needed to use.
These costs makes reproducing the building styles and materials of 100 years ago virtually impossible for most builders. But even for those who are willing to pay a premium for a historic look, there are environmental costs to consider.
Manufacturing and transporting masonry, and other heavy materials, contributes greatly to climate change. Bricks have to be burned — and these days that means using fossil fuels. Concrete is even worse, and its manufacture is responsible for a stunning proportion of global carbon emissions.
By contrast, wood is abundant and accessible. It can be replenished with relative ease, and it absorbs carbon from the atmosphere. (It then continues to hold carbon after trees are felled, only releasing it when they burn or rot.)
Because wood doesn’t weigh as much as brick, stone, or concrete it also burns less gas to transport.
For those seeking points towards LEED certification — the gold standard for environmentally friendly buildings —builders must use materials from within 500 miles of the construction site. As local brick manufacturers become rarer in the mid-Atlantic region, that’s become a tougher lift.
“Endurability versus sustainability,” said Jeremy Avellino, founder and principal of Bright Common Architecture. “No, we don’t build them like they used to. We don’t have the resources and we can’t ignore the climate science that shows us that we can’t build that way anymore.”
But are our buildings, and the materials used to build them, actually worse?
Newer composite materials are undoubtedly more affordable than brick and stone, but will they age as well?
It depends on the context — every material has its pros and cons, said Nishant Garg, an assistant professor at the University of Illinois at Urbana-Champaign, who researches construction materials.
When it comes to ability to withstand mechanical stress, metals are strongest, followed by ceramics, like bricks. Then comes wood. On the other hand, if you’re looking for protection against heat and cold, wood is the best insulator while metal is the worst.
While wood is prone to warping and shrinkage, metals can corrode. And bricks and mortar are porous, so they require good design and workmanship to keep water out of interior building layers.
But nowadays, with advances in materials science, these intrinsic properties may be less limiting than before. Composite, or hybrid, materials are breaking down the traditional categories of materials, Garg said. By mixing multiple materials together, you can engineer something that looks like wood, but is strong like metal, and lightweight like vinyl.
“You cannot really trust what you see,” Garg said. “Now it is so sophisticated that it’s very easy to fool people.”
That also gives people more aesthetic options in choosing a new home, which can change the social fabric of neighborhoods, according to Garg.
“It’s our ability to have these materials, with different kinds of shapes and colors, that we can change neighborhoods very drastically,” he said. “That definitely affect rents and the people who want to live there.”
Architectural conservationist John Carr has his concerns about composite materials. He works with older materials and argues that brick, stone, and hardwood have shown that they are survivors.
“When you are building with materials that have been around for centuries, brick and stone and dimensional lumber, they have a track record,” said Carr, who is the founder of Kensington-based firm Material Conservation.
“You can look at what’s been built and what is still standing. I don’t have a crystal ball, but I would be buying a house built in the 1880s if I were trying to protect my investment and my asset.”
Recent headlines haven’t inspired confidence in new construction in the region. Across the country, but especially in Pennsylvania, some newly built homes are rotting from the inside, their soft wooden interior flaking away behind stucco or vinyl siding. Multiple major homebuilders have found themselves tangled in multi-million dollar lawsuits.
But many experts argue that it wasn’t the newer materials that were necessarily at fault in these cases.
“New materials don’t scare me, it’s how they are used,” Carr said.
Instead, these homes were built in such a way that allowed water into the structure, behind the facade, without giving it a good way to get back out.
Avellino says that every stick-frame house shooting up in an old neighborhood shouldn’t be seen as a future case of home rot.
“It’s not that heavy masonry is better than wood frames,” Avellino said. “You go down to Elfreth’s Alley, one of the oldest streets in Philadelphia, and many of those buildings are wood framed and they are from the 1700s. They are some of the oldest buildings in Philadelphia.”
Avellino feels that the dichotomy between new and old materials should be retired entirely. He designs fossil-fuel free houses build of all kinds of materials. For him, the important thing is minimizing the carbon footprint of a house over its entire lifecycle.
Instead of a sentimental attachment to brick and stone, he said, we need to focus on how things can be built today, and what design can do for us in a changing world.
“I have hope that we will transcend this tired nostalgia, about a past that was really complicated,” he said.