What Illinois’ BUILD Act Means for Your Development Project

Note: The BUILD Act (Building Up Illinois Development Plan) was introduced in the Illinois General Assembly in February 2026. As of publication, this legislation is proposed and has not yet been enacted. The information below reflects the bills as introduced. We will update this post as the legislation advances.

In mid-February 2026, Governor Pritzker announced the Building Up Illinois Development Plan, citing local regulations that have made it “too difficult and costly to build new housing” across the state. The BUILD Plan is not a single bill. It is a package of legislative proposals now moving through the General Assembly that would reshape ADU zoning, parking requirements, permit review timelines, and the approval process for multi-unit housing in Illinois municipalities.

For developers, property owners, and investors working in Cook, Lake, or DuPage County, the proposals carry direct implications for project feasibility, entitlement timelines, and site selection decisions.

What Is the BUILD Plan and How Is It Structured?

The BUILD Plan was introduced through HB 5626 (a 40-page omnibus housing bill) in the House, along with Senate Bills 4060 through 4064 and SB 4071, each targeting a specific area of housing regulation.

The significance for the Chicago development market: several of these proposals would override local zoning restrictions that currently add months and high cost to housing projects.

Right now, every municipality in the Chicago metro sets its own rules for ADUs, multi-family projects, parking minimums, and permit review. The BUILD Plan would establish statewide floors that local governments cannot go below.

How the BUILD Act Changes ADU Zoning in Illinois

The current ADU zoning landscape across suburban Illinois is inconsistent. Some municipalities allow accessory dwelling units by right. Many require a special use permit or conditional use approval. Others do not address ADUs at all, which effectively prohibits them.

SB 4071 would change that framework. Under the proposed legislation:

• Every municipality would be required to permit ADUs in all zoning districts that allow single-family homes
• No additional requirements related to lot size, setbacks, aesthetic standards, design review, frontage, or space limitations beyond what applies to single-family homes
• Municipalities could not require a familial relationship between occupants of an ADU and the principal structure

Chicago’s own ADU ordinance, which took effect April 1, 2026 after a unanimous 46-0 City Council vote in September 2025, still gives aldermen substantial control over where ADUs are permitted in their wards. The BUILD Plan’s ADU provisions would go further by creating a statewide standard that removes that discretionary layer entirely.

For developers and property owners, this could open ADU construction on thousands of parcels where it is currently prohibited or requires months of approvals.

What “By Right Zoning” Means Under the Middle Housing Provisions

SB 4060 targets what the legislation calls “middle housing”:

• Duplexes, triplexes, and fourplexes
• Cottage clusters and townhomes
• Attached and detached courtyard housing
• Stacked flat-plexes

The bill proposes two critical changes:

• Municipalities could not impose bulk, setback, lot area, or other standards on middle housing that are more restrictive than what applies to single-family detached homes in the same district
• Municipalities could not require discretionary review (such as a special use permit or variance) for middle housing unless the same process is required for single-family construction

This is the by-right zoning concept in practice. If a single-family home can be built without a hearing, a triplex meeting the same dimensional standards could be built the same way. The discretionary approval process that currently adds 3 to 6 months to multi-unit projects in many suburban municipalities would be eliminated for qualifying middle housing.

Parking Reform and Permit Review Deadlines

Two additional proposals address issues that routinely add cost and delay to housing projects.

Parking reform (SB 4064). Starting January 1, 2027, municipalities would be prohibited from requiring more than:

• 0.5 parking spaces per multifamily dwelling unit
• 1 parking space per single-family home
• Even lower minimums for affordable housing projects and dwellings under 1,500 square feet

Permit review deadlines (SB 4063). Municipalities would face mandatory timelines:

• 15 business days for initial review of single-family and two-family projects
• 30 business days for initial review of multifamily, mixed-use, or commercial projects
• 10 business days for subsequent reviews after revisions
• 2 business days for inspections

If a municipality misses these deadlines, the applicant could retain a qualified third-party professional to conduct the review or inspection.

What Developers Should Monitor as the BUILD Act Advances

These bills were introduced recently, and some or all may face amendments, debate, and delays during the spring legislative session. The home rule preemption language is likely to draw significant municipal opposition.

Priority items to track:

• Amendment activity. The bills as introduced are aggressive. Expect compromises, particularly on the ADU and middle housing preemptions.
• Home rule challenges. Illinois has strong home rule traditions. Municipal lobbying organizations will push back on provisions that override local zoning authority.
• Implementation timelines. Many provisions include delayed effective dates. SB 4064’s parking reforms would not take effect until January 2027.
• Local response. Some municipalities may move to adopt updated standards before statewide mandates take effect, creating a transitional period of inconsistent rules.

How Birchwood Law Supports Development Projects

Whether the BUILD Act passes in its current form or is amended, zoning and entitlement requirements in Cook, Lake, and DuPage County will continue to evolve. If you are evaluating a development site and need to understand how current or proposed regulations affect your project, we can help assess the local zoning framework and identify the most efficient path to approval. Contact us to discuss your project.

This content is for informational purposes only and does not constitute legal advice. The information provided does not create, and receipt of it does not constitute, an attorney-client relationship. You should not act upon this information without seeking advice from an attorney licensed in your own state or country.