The building firm is under fire for its threat to close a swimming pool to pupils while allowing male nudists to book it in the evenings.
Swimming lessons at Northumberland Park school in Haringey, north London were at risk when Jarvis demanded an extra pound;50,000 to provide lifeguards, teachers say.
At the same time, bookings were taken for the Gymnos club, which offered naked wrestling, massage and skinny-dipping for 30 men two evenings a week.
The club supplied its own lifeguards.
Haringey council used to employ lifeguards until the mixed school was rebuilt under the private finance initiative and the pool staff were transferred to Jarvis.
A teacher said: "They carried on doing their jobs and being on hand if the children got into trouble, but Jarvis has now tried to charge the school for the services they provide."
Andy Kilpatrick, headteacher, said: "It appears that Jarvis is not required to put on lifeguards, but if the pool is to function they must be there and they have to be paid."
Jarvis has now banned the nudists after receiving complaints. It said it was unaware of the club's activities. "The group simply described itself as a swimming club when it made the booking."
Jarvis narrowly avoided bankruptcy and reported a pound;256 million loss last year, due in part to penalties for delays on school projects. On Wednesday, it announced it was selling its bidding arm, which tenders for school construction projects.