ADU — Attached ADU Cost in Chicago, 2026

Why attached adu × Chicago produces this band

A attached adu scope for a adu in Chicago combines two price levers: scope and metro labor rates. Attached ADUs share a wall with the primary house. Needs its own entrance, fire-rated separation, and (in most jurisdictions) independent utility metering — but shares the site's foundation-extension cost. Against the national median remodel labor rate, Chicago runs 15% above the national median — so the attached adu band comes in 5% below the mid-range, then scales 15% above the national median on top of that. Permit timelines for residential work in Chicago typically run 6-14 weeks, which is the window you plan your design and decision sequence against. This page gives you the actual 2026 Chicago bands for this exact combination, plus the three cost drivers Baily asks about first when scoping the project live.

What drives cost for a attached adu scope

• ·Fire-rated wall assembly (typically 1-hour, sometimes 2-hour)
• ·Independent utility service drops
• ·Shared-wall sound isolation (STC 50+)
• ·Grading and drainage on the new footprint

What makes Chicago different

• Labor — Union trades (carpentry, electrical, plumbing) are the majority of licensed remodel labor — premium over national median.
• Labor — Winter shuts down most exterior trades Dec-Feb, compressing schedules into a 9-month season.
• Labor — Chicago Prevailing Wage Ordinance drives labor costs on any publicly-touching work.
• Material — Midwest steel and framing lumber are priced competitively vs coasts.
• Material — Masonry restoration (common in pre-war Chicago brick) uses specialty materials with long lead times.

Chicago rules that affect this scope

• Chicago DOB self-certification is available for registered architects — compresses permit timelines.
• Landmark districts (e.g. Lincoln Park, Old Town Triangle) require Commission on Chicago Landmarks review in addition to DOB permit.
• Chicago Energy Conservation Code (IECC 2021) applies to all work changing envelope or HVAC.
• Two-flat and greystone conversions frequently trigger zoning variance — timeline extension of 8-14 weeks.

Scope your adu with Baily.

Baily asks the eight questions that determine where your project lands inside the $197K-$415K band for Chicago and hands the scoped brief to one licensed builder.

Related pages

Questions LA homeowners actually ask

• What is the 2026 cost range for a attached adu scope adu in Chicago?

  $196,650-$415,150, with the median landing near $305,900. The range reflects finish tier and layout complexity within the attached adu scope; the Chicago labor multiplier of 1.15× vs national median is baked in.

• How long does a attached adu scope adu take in Chicago?

  22-32 weeks of on-site construction for the attached adu scope, plus 6-14 weeks of permit review in Chicago if the scope requires a permit. Cosmetic-only refreshes often skip permits; anything touching plumbing, electrical, or structural does not.

• What is the single biggest budget-overrun risk for this scope?

  Utility separation surprises — some markets require a new electrical service drop from the street, not just a sub-panel. Utility-company coordination adds 6-10 weeks and $8-14K.