Earlier this month, about 350 people gathered in the Rockaways to watch a movie about concrete. They sat on the beach in folding chairs with their feet in the sand, facing a screen supported by large concrete blocks. The makeshift theater, called the Arverne Cinema, is located on a plot of land next to a defunct concrete plant. Concrete abounds.

“The History of Concrete” served as the ninth annual Rockaway Film Festival's headliner. It is documentarian John Wilson's first feature-length film, which explains the big turnout: Wilson earned a passionate fan base with his HBO series “How To With John Wilson,” in which he brought viewers along as he traveled across New York City and beyond, seeking life lessons on, say, how to make small talk, how to cover your furniture and how to find a parking spot — all while highlighting the city’s oddball charm.

It only follows that Wilson would attempt a documentary about concrete, given his taste for the unexpected. He relished the challenge of making such a lackluster subject interesting: “You have nobody to rebel against except yourself sometimes,” he told Gothamist in an interview just before the Rockaway screening.

He had arrived at the green room in a light blue collared shirt and khakis with a canvas tote bag slung over his shoulder, the same Brooklyn everyman uniform he sported in the glimpses “How To” viewers were afforded of him behind the camera.

Wilson has built a career off his ability to find meaning in the mundane. “The History of Concrete,” which opens Friday, begins with his journey to learn more about the material after discovering cracks in the foundation of the multistory house he owns in Ridgewood, Queens. But in true Wilson fashion, he pursues a series of side quests that end up revealing a lot about the physical and social structures that uphold our city.

Sam Fleischner, a filmmaker and co-founder of the Rockaway Film Festival, met Wilson years ago because they ran in similar professional circles. He said that he admires Wilson’s quirky style of documentary filmmaking, which in recent years has involved second-person narration over clips of life unfolding around the city (e.g. people yelling at partners, embracing friends or, in one specific instance from “How To,” forcing a pigeon into a plastic bag from Duane Reade).

Flesichner described Wilson as “a comedic visual poet.”

“I feel like the world just gets more and more absurd,” Fleischner said. “It’s just out of control how crazy everything is, and it’s so nice to have people who can present it in a way where you can just kind of laugh at it and accept it without judging it.”

John Wilson at the Rockaway Film Festival. He chose to pose in the corner.

Nearly 20 years ago, when Wilson was a film student at Binghamton University, he set out to make a documentary short about a strip club he discovered in what he said looked like a condemned building under a highway overpass in Upstate New York. The project was short-lived; to the chagrin of the strip club’s owners, Wilson lost interest in the film as soon as he entered the premises and met a male patron with a balloon fetish — who then revealed that he also hosted parties for people who shared his unusual fixation. That was clearly the stronger narrative.

“I just started following him and making the film with him instead,” Wilson said. “A lot of the time, you throw out your first version of whatever the thing was, and it’s fine.”

The resulting short film, “Looners,” became one of the first projects to adopt the earnest tone for which Wilson is now renowned. As a documentarian, he holds back personal opinions on the people and behaviors he captures, instead adopting an almost anthropological approach. Even now, while looking back on the short film, Wilson explained without a shred of irony in his voice that, in the balloon fetish world, “there are two different camps … poppers and non-poppers.”

“The History of Concrete” started with a similar curiosity about something fascinating to Wilson. He realized how little he knew about concrete while talking to a neighbor about the cracks in his foundation, so he attended a professional conference for concrete industry workers and shadowed a pair of concrete finishers as they poured a back patio. But like Wilson’s other work, the movie becomes more layered as he strays from the original premise to chase his curiosities. He travels to Ohio to visit the country’s first concrete road, for instance, and somehow ends up on a hunt for Chef Boyardee’s grave.

The most heartfelt throughline of the film involves Jack Macco, a liquor salesperson and rock musician. Wilson befriends Macco after attending one of his concerts in Queens and eventually attends a funeral service for Macco’s late fiancée, a respected judge. (It’s a long story, but all of this is in fact tangentially related to the concrete plot.)

“Jack was a musician playing small bars around New York and Long Island, and his confidence was really infectious,” Wilson said. “He was just a great swimming buddy to have because every time I would feel really down, he would be really optimistic.”

He added, “There are certain relationships that I have within the film that I just wanted to spend time with. The movie is partially about how it is important in certain ways to give yourself a set of rules, even if they’re only there for you to betray them.”

When Wilson was young, he borrowed a video camera from his father and never gave it back. He grew up on Long Island and made movies out of boredom, a feeling he said is “important to embrace because when you’re not actively fixated on something, you’re allowed to drift.”

Wilson didn’t use his narration to carry viewers through his earlier work the way he does in both “How To” and “The History of Concrete.” He only started making documentaries in this format in the 2010s, when he realized it was a good way of forcing himself to overcome his personal insecurities.

“I’m generally kind of socially anxious,” he said, noting that he used to dislike the sound of his voice and doubted the quality of his comedic writing. “I just wanted to throw all of those anxieties into a single container and just be like, ‘I’m going to do all of them at once.’”

Wilson received three Emmy nominations for “How To,” two of which were for writing — a feat he described as “my biggest achievement so far.”

“I think that’s insane,” he continued. “It’s not for filming. It’s not for directing. It’s for writing, you know? Not to break my own arm patting myself on the back, but it’s crazy how much you can change and progress when you just start doing something you’re scared of.”

Earlier this year, the Mamdani administration recruited Wilson to shoot a public service announcement about its efforts to reduce scaffolding across the city (a topic Wilson explored in an early episode of “How To”). It’s hardly a hot-button topic for most people, but is this more discernible step toward politics a sign of what is to come?

Wilson said he is currently working on “a couple of big projects” but remained mysterious about the details, perhaps because his journeys are so unpredictable: He knows what they’re supposed to be about right now, but his curiosity could lead him anywhere.

In the meantime, he is choosing to focus on the rollout of what he initially hoped would become “the definitive movie about concrete.” He gets points for trying.

“I obviously drift pretty far from that initial conceit,” Wilson said. “But I think this movie will still please concrete fans and concrete critics alike.”