For decades, DIYers and construction pros have picked up yellow and red bags of Quikrete concrete mix from the shelves of America’s big box stores like Home Depot and used it for everything from anchoring mailboxes to patching driveways and making outdoor benches and steps. That in turn has generated billions of dollars for the little-known company and the little-known family behind the brand.

But their time in the shadows may have come to an end. In February 2025, the privately-held building materials firm made a big splash when it paid $11.5 billion to acquire publicly traded competitor Summit Materials. The deal, which Forbes estimates boosted Quikrete’s revenue by around 50% to an estimated $12 billion, helped propel the Atlanta-based company onto Forbes’ first ever ranking of America’s Largest Family Businesses, published this week, at No. 43. Based on Forbes’ estimates, Quikrete is the 17th most valuable privately-held family business in America, making its founding Winchester family one of the country’s richest clans, worth an estimated $18 billion, thanks to their estimated 100% ownership of Quikrete.

“We’re proud of our heritage as an American, family-run company that has helped revolutionize the building and home improvement industries,” said Quikrete’s longtime former CEO Jim Winchester in a press release celebrating the company’s 75th anniversary in 2015. “From day one, my father Gene Winchester was driven to meet the needs of both contractors and homeowners with the highest-quality products at fair market value, and that commitment remains a core value of Quikrete today.”

That marked a rare public statement for the ultra-private Winchesters, who have managed to keep a low-profile despite building and owning a company that Forbes estimates is now more valuable than bigger-name family businesses like Nordstrom, Wawa and Kohler. Though a non-family member, Quikrete’s former president and chief operating officer Will Magill, has been CEO since around 2020, Jim Winchester, 82, served as chief executive until at least 2015 and still sits on the company’s three-person board, alongside his brothers Jack, 80, and Dennis, 77.

The Winchesters barely ever speak to the press, and little information about the family is available online, save for a few listings of roles with community organizations like the Buckhead Coalition in the affluent Buckhead neighborhood of Atlanta, or as current and former members of the board of their alma mater, John Carroll University in Cleveland. The family has also appeared in Federal Election Commission filings detailing their contributions to mostly Republican politicians and their political committees, the largest of which was a $103,000 donation by Dennis Winchester to the Trump 47 Committee in 2024. A representative for Quikrete and the Winchesters declined multiple requests for interviews and to comment for this story, telling Forbes that the family did not wish to be profiled for privacy reasons.

Quikrete got its start as a small building materials........

© Forbes