One of the sibling co-founders of Equinox cheated a construction company out of nearly $4.5 million in two Westchester development projects, new court papers allege.

Vito Errico — who founded the upscale gym chain with siblings Lavinia and Danny in the early 1990s — hired small business owner Gioncondo “Jack” DiPietro and his company DiPietro Construction Corp. to do the excavation work on two projects in Pleasantville in 2017 and 2018, according to the filings from Wednesday.

Errico convinced DiPietro to forgo regular pay — and instead accept equity in both of the new buildings — after he was paid the bare cost of labor and provided his own equipment for free, the papers said.

By contrast, on the first job that DiPietro did as a subcontractor in 2006 on Errico’s 12,000-square-foot Armonk home — which has an indoor pool and basketball court — he charged $1,500 for an eight-hour day for the cost of using one of his excavators and the cost of hiring an operator for the machine, the court filings claim.

DiPietro first began working for Errico under these special terms in 2017 on a mixed residential and retail space building to be located at 39 Washington Avenue in Pleasantville. And before that work was complete, Errico in 2018 locked DiPietro in under the same pay structure for excavation work on a residential building in the same town located at 70 Memorial Plaza, the court papers allege.

But Errico “knew he would never honor his end of the deal and instead planned on taking advantage of DiPietro by getting the value of the labor at less than true cost and the machinery for free and similarly not paying or transferring the equity,” the court papers allege.

“Errico took a page out of the unscrupulous developer’s playbook, which essentially states ‘I am so big, go ahead and sue me and I will drown you in legal costs.’ That is exactly what Errico is doing in this case,” the suit charges.

Errico – who listed his Armonk mansion for $8.88 million in 2019 – “uses his success to overwhelm, impress, take advantage of and really push around regular people who would like to believe that Errico is an honest businessman with good intentions, which as this case shows, is not true,” the suit alleges.

DiPietro’s claims are lodged in two separate suits that were originally filed in November in Westchester Supreme Court and just updated this week. He claims he’s owed over $3.5 million for the Memorial Plaza project and over $1 million for the Washington Avenue development.

“The complaints detail a pattern of deceit and broken promises made to my client,” DiPietro’s lawyer Eric Grayson told The Post. “I believe the jury will see right through the defendant and hold for my client.”

Errico’s lawyer Stephen Meister told The Post: “Mr. DiPietro was forced to amend his complaint by the court.

“He still has it wrong. We expect the court to find that Mr. DiPietro’s claims are meritless.”