How architectural tools with a cosmic twist help strengthen old Pittsburgh homes
Five-pointed, colorful metal stars are fastened to the exterior of many of Pittsburgh’s old, brick houses. But these stars aren’t necessarily displaying the patriotism of the residents. They’re important anchors that reinforce bowing brick facades.
“What you see on the outside is more of a decorative plate that is attached to a tie rod that goes back through some floor joist framing, typically, and then is anchored to those to help support the walls,” said Travis Kreidler, architect with Desmone Architects in Pittsburgh. “They have an important role.”
“Star bolt” isn’t the only term these handy hidden anchors use. Sometimes they just go by “tie rods” or “star anchors,” and they take many shapes, including rosettes, squares or circles.
“With the star shape, it's kind of like fingers,” Kreidler said. “They reach out and grab a hold of more of the brick’s surface, as well as playing into a more decorative element.”
Many old brick row houses are framed with floor and roof joists “spanning in one direction, usually in the short direction,” according to Peter Margittai, architect and owner of Margittai Architects. If it’s a rectangular building, he said, front and back walls aren’t well secured to the framing. They’re only connected at the edges and by the roof, often by older, less effective mortar.
Over time, the walls will start to bow, making the structure vulnerable. To secure the building, a threaded rod with a star bolt plate can be drilled through the brick wall until it reaches the wood framing. The plate makes sure the rod doesn’t slide through the hole in the brick.
Most often, Margittai said, the star bolts are installed between windows. They reach through and grab the floor joists below the windows, so the exterior stars appear in a nice row. In row houses, like the many in a neighborhood like Lawrenceville, the bolts are often above the front door, between the first and second stories. They could also appear near the lower part of the home, connected to the first floor joists.
The bolts often end up being the most cost-effective solution for homeowners or landlords.
“This is kind of an easy fix,” Margittai said. “It’s the most common and sort of the least expensive way to do it.”
If a building’s structural issues are more severe, it might require larger and longer plates, or even exterior steel framing. On Pittsburgh’s South Side, another neighborhood with old housing stock, Margittai gave the example of an upstairs apartment unit on Carson Street. The brick facade was “peeling off the building at one point,” so architects and engineers built a “pretty intense steel structure” inside the wall to tie back the masonry walls.
“Obviously something was really going sideways that they had to address,” he said.
While star bolts are used to bolster bulging brick walls in many eastern U.S. rowhomes, Travis Kreidler said they’re used to stabilize homes in the west in case of a seismic event like an earthquake.
He said many 18th and 19th century buildings were held together by lime mortar, which isn’t as strong as what many construction crews use today. The widespread adoption of Portland cement, for example, means new homes likely won’t require the star bolts. But they’re still a reliable way to keep a building strong without sacrificing aesthetics.
While we’re on the subject of steel beams…
On her morning commutes, Good Question! asker Jen Ackerman noticed a beam protruding from the building at 4 Smithfield Street.
“It can be seen from Ft. Pitt Blvd,” she wrote. “What’s going on with that?”
Halfway up the 12-story neoclassical structure it looks like someone pushed a beam too hard into the riverside-facing wall and it popped out.
Unlike the star bolts, however, building owner Frank Ewing said this beam served a different practical purpose. Ewing’s family has owned the building since 2006, but he said they call it “The House Building” after another former owner, James House.
“[It] was originally a hotel built in the late 1800’s as a six-story building,” Ewing wrote. “At some point in the early 1920's, another six stories were added to it. This beam would have been used to lift materials up the side of the building.”
In lieu of elevators or cranes, crews would sometimes use pulley-like systems. They aren’t as subtle as the star joints, but important in their own way.