Lost Language Takes Its Chicago Social Sauna Indoors With an $800,000 Ravenswood Build
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Sauna culture and community
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- Lost Language Ravenswood
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A city permit issued Aug. 24 covers saunas and a plunge pool at the building where the outdoor social sauna opened last November. One of its founders started Friday Morning Swim Club.
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Lost Language, the outdoor social sauna on Chicago’s North Side, is moving indoors. The city issued a permit on Aug. 24 for an $800,000 renovation at 4510 N. Ravenswood Ave. that includes “a wellness area with plunge pool and saunas,” and the sauna is closed while the work goes on. Its website says the team is building “our first brick & mortar home in Ravenswood.”
The Chicago permit covers interior alterations that subdivide tenant space in an existing one-story building: new partitions, accessible restrooms, a laundry room and the wellness area, with mechanical, electrical and plumbing work throughout. It doesn’t say how many saunas there will be, what heats them or how big the plunge pool is. The space needs a certificate of occupancy before it can open, the last of the sign-offs a bathhouse build has to clear.
Lost Language didn’t respond to a request for comment by publication on Tuesday.
Lost Language Ravenswood at a glance
- Address 4510 N. Ravenswood Ave., Chicago
- Permit No. 101083356, renovation and alteration, applied for May 11 and issued Aug. 24, 2026
- Reported cost $800,000
- Scope Saunas, a plunge pool, accessible restrooms and a laundry room
- Team on the permit Architect Craig M. Reschke, general contractor Trellis Group, plumbing contractor SMM Mechanical and electrical contractor Battaglia Industries
- Opening Not announced
The outdoor version held about 15 people
Lost Language held a free grand opening on Nov. 15, 2025. Its website describes an electric sauna that ran Thursday through Sunday and fits about 15 people, a wood-fired sauna that is out of commission, two cold pools that hold three or four people each and two outdoor showers.
The building’s other occupant, the gym Feast Fitness, lists the sauna and cold plunge as an on-site amenity. A plunge pool indoors brings the venue under the health-code questions cold plunges are raising across the industry.
A lakefront swim club’s founder moves to private property
The company’s story page is signed by its founders, Andrew and Sarah. Andrew Glatt, whose name is on the permit, co-founded Friday Morning Swim Club in 2021, the Montrose Harbor meetup that grew from eight swimmers to thousands. Chicago magazine named him and co-founder Nicole Novotny Chicagoans of the Year in 2023.
In May 2024 the pair said the club wouldn’t return to Montrose Harbor, CBS Chicago reported, after Glatt put the Chicago Park District permits for a season at $150,000 to $175,000 at minimum. The Ravenswood project runs on private property under a city building permit rather than a Park District permit for public lakefront.
The build adds Chicago to the list of neighborhood sauna clubs that started small before committing to a permanent space, as Sauna Jungle is doing in Arlington.
Lost Language posts updates on its website and Instagram, and the project is on the SaunaNews bathhouse opening tracker.
