Lincoln Square Greystones: Basement Suite with Legal Egress

The building

A 1910 greystone two-flat in Lincoln Square, one of Chicago’s most intact late-19th/early-20th century residential neighborhoods. The building’s two upper floors had been renovated in 2019; the basement, used for storage, was unfinished, with a dirt floor over a concrete perimeter footing in the front section and a 1950s concrete slab in the rear.

The objective: create a legal, rentable basement unit with a full kitchen, a full bath, a bedroom with compliant egress, and a living area, approximately 750 usable sq ft within the 1,100 sq ft footprint.

The waterproofing decision

The basement had a history of water intrusion in the front section, where the original dirt floor sat against a limestone rubble foundation. The firm’s assessment: interior French drain with sump pump to manage the front section, combined with hydraulic cement injection at the visible crack in the rear poured wall near the hatch opening.

Exterior waterproofing was considered for the front section and rejected: the cost of excavating a greystone on a 25-foot Chicago lot, with an adjacent property 8 feet to the north, was $25,000–$35,000 for that section alone. The interior drainage system at $9,500 achieves the same functional result for a rental application.

The front floor was poured with a new 4” concrete slab after the drainage system was installed.

The egress window variance

Chicago’s 25-foot standard lot width creates a well-documented problem for basement egress compliance. The required window well projects 36 inches from the foundation face into a 4-foot city parkway strip. Under Chicago zoning, window wells that project into the public way require a variance from the Department of Planning and Development.

The variance process takes 6–10 weeks at DPD. The firm filed simultaneously with the building permit application, accurately cited the precedent established by prior greystone variance approvals in the 60625 zip code, and provided the window well engineering drawings with the variance filing up front, before the city asked. DPD approved in 7 weeks.

Two egress windows were installed: one in the bedroom at the front (compliant opening size: 5.9 sq ft net clear), one emergency egress in the living area at the rear. Window wells are galvanized steel with concrete footings, with drain channels tied into the interior sump system.

Mechanical and systems work

Electrical: New sub-panel for the basement unit, completely independent circuits from the upper floors. Separate meter provision installed per Chicago multi-unit code.

Plumbing: New supply runs to the basement kitchen and bath from the main stack above. A sewage ejector pump handles the basement drain lines, which sit below the city sewer main. New water heater, tankless electric, to avoid routing gas appliance flue through the occupied unit.

HVAC: Mini-split system (LG Art Cool) with two wall-mounted heads covering the kitchen/living zone and the bedroom. No ductwork penetrations into the upper floors.

Finish

LVP flooring throughout, spray-texture drywall (chosen for its tolerance of minor floor flex in a Chicago basement), recessed LED lighting on dimmers, quartz kitchen counters, subway tile bath. Concrete ceilings left exposed in the kitchen/living area where beam height allowed, a design decision consistent with Lincoln Square’s industrial-influenced aesthetic.

Outcome

The unit passed Chicago’s rental inspection in February 2026. Rental income at Lincoln Square market rates for a legal basement one-bedroom produces a cap rate of approximately 8.4% on the renovation cost, a return that reflects both the quality of the neighborhood and the premium that legal rental status commands over an unpermitted basement unit.